Store multiple choice field in db using Django

I have three models class as below.

from django.forms import ModelForm


RATING_CHOICES = ((1, "Weak"), (2, "Average"), (3, "Good"), (4, "Excellent"))


class Question(models.Model):
    text = models.CharField(max_length=100)
    
    def __str__(self):
        return self.text


class Teacher(models.Model):
    name = models.CharField(max_length=50)

    def __str__(self):
        return self.name


class Answer(models.Model):
    question = models.ForeignKey(Question, on_delete=models.CASCADE)
    teacher = models.ForeignKey(Teacher, on_delete=models.CASCADE)
    answer = models.IntegerField(choices=RATING_CHOICES, default=1)

in the template I have access to my fields in this way:

  {% csrf_token %}
    <select name="teacher_selected">
      {% for teacher in teacher %}
        <option value="{{teacher}}">{{teacher}}</option>
        {% endfor %}
    </select>

  {% for question in question %}
      <ol>{{ question.text }}</ol>
      {% for choice in rating_choices %}
        <input type="radio" name="question_{{question.id}}" value="{{choice.0}}">{{choice.1}}
      {% endfor %}

  {% endfor %} <br>

  <input type="submit" value="Vote">
</form>

Now I know how to get the value of Teacher class teacher = request.POST.get(‘teacher_selected’), but I do not know how to store answers since it is a little different compare to teacher.
I asked this question in StackOverFlow but did not get the clear answer. They just gave me hints. For example, use formset or linking part 4 of Django documentation.
I need a proper views.py for my codes.

What is GEEK

Buddha Community

Store multiple choice field in db using Django

Chloe Butler

1667425440

Pdf2gerb: Perl Script Converts PDF Files to Gerber format

pdf2gerb

Perl script converts PDF files to Gerber format

Pdf2Gerb generates Gerber 274X photoplotting and Excellon drill files from PDFs of a PCB. Up to three PDFs are used: the top copper layer, the bottom copper layer (for 2-sided PCBs), and an optional silk screen layer. The PDFs can be created directly from any PDF drawing software, or a PDF print driver can be used to capture the Print output if the drawing software does not directly support output to PDF.

The general workflow is as follows:

Design the PCB using your favorite CAD or drawing software.
Print the top and bottom copper and top silk screen layers to a PDF file.
Run Pdf2Gerb on the PDFs to create Gerber and Excellon files.
Use a Gerber viewer to double-check the output against the original PCB design.
Make adjustments as needed.
Submit the files to a PCB manufacturer.

Please note that Pdf2Gerb does NOT perform DRC (Design Rule Checks), as these will vary according to individual PCB manufacturer conventions and capabilities. Also note that Pdf2Gerb is not perfect, so the output files must always be checked before submitting them. As of version 1.6, Pdf2Gerb supports most PCB elements, such as round and square pads, round holes, traces, SMD pads, ground planes, no-fill areas, and panelization. However, because it interprets the graphical output of a Print function, there are limitations in what it can recognize (or there may be bugs).

See docs/Pdf2Gerb.pdf for install/setup, config, usage, and other info.

pdf2gerb_cfg.pm

#Pdf2Gerb config settings:
#Put this file in same folder/directory as pdf2gerb.pl itself (global settings),
#or copy to another folder/directory with PDFs if you want PCB-specific settings.
#There is only one user of this file, so we don't need a custom package or namespace.
#NOTE: all constants defined in here will be added to main namespace.
#package pdf2gerb_cfg;

use strict; #trap undef vars (easier debug)
use warnings; #other useful info (easier debug)


##############################################################################################
#configurable settings:
#change values here instead of in main pfg2gerb.pl file

use constant WANT_COLORS => ($^O !~ m/Win/); #ANSI colors no worky on Windows? this must be set < first DebugPrint() call

#just a little warning; set realistic expectations:
#DebugPrint("${\(CYAN)}Pdf2Gerb.pl ${\(VERSION)}, $^O O/S\n${\(YELLOW)}${\(BOLD)}${\(ITALIC)}This is EXPERIMENTAL software.  \nGerber files MAY CONTAIN ERRORS.  Please CHECK them before fabrication!${\(RESET)}", 0); #if WANT_DEBUG

use constant METRIC => FALSE; #set to TRUE for metric units (only affect final numbers in output files, not internal arithmetic)
use constant APERTURE_LIMIT => 0; #34; #max #apertures to use; generate warnings if too many apertures are used (0 to not check)
use constant DRILL_FMT => '2.4'; #'2.3'; #'2.4' is the default for PCB fab; change to '2.3' for CNC

use constant WANT_DEBUG => 0; #10; #level of debug wanted; higher == more, lower == less, 0 == none
use constant GERBER_DEBUG => 0; #level of debug to include in Gerber file; DON'T USE FOR FABRICATION
use constant WANT_STREAMS => FALSE; #TRUE; #save decompressed streams to files (for debug)
use constant WANT_ALLINPUT => FALSE; #TRUE; #save entire input stream (for debug ONLY)

#DebugPrint(sprintf("${\(CYAN)}DEBUG: stdout %d, gerber %d, want streams? %d, all input? %d, O/S: $^O, Perl: $]${\(RESET)}\n", WANT_DEBUG, GERBER_DEBUG, WANT_STREAMS, WANT_ALLINPUT), 1);
#DebugPrint(sprintf("max int = %d, min int = %d\n", MAXINT, MININT), 1); 

#define standard trace and pad sizes to reduce scaling or PDF rendering errors:
#This avoids weird aperture settings and replaces them with more standardized values.
#(I'm not sure how photoplotters handle strange sizes).
#Fewer choices here gives more accurate mapping in the final Gerber files.
#units are in inches
use constant TOOL_SIZES => #add more as desired
(
#round or square pads (> 0) and drills (< 0):
    .010, -.001,  #tiny pads for SMD; dummy drill size (too small for practical use, but needed so StandardTool will use this entry)
    .031, -.014,  #used for vias
    .041, -.020,  #smallest non-filled plated hole
    .051, -.025,
    .056, -.029,  #useful for IC pins
    .070, -.033,
    .075, -.040,  #heavier leads
#    .090, -.043,  #NOTE: 600 dpi is not high enough resolution to reliably distinguish between .043" and .046", so choose 1 of the 2 here
    .100, -.046,
    .115, -.052,
    .130, -.061,
    .140, -.067,
    .150, -.079,
    .175, -.088,
    .190, -.093,
    .200, -.100,
    .220, -.110,
    .160, -.125,  #useful for mounting holes
#some additional pad sizes without holes (repeat a previous hole size if you just want the pad size):
    .090, -.040,  #want a .090 pad option, but use dummy hole size
    .065, -.040, #.065 x .065 rect pad
    .035, -.040, #.035 x .065 rect pad
#traces:
    .001,  #too thin for real traces; use only for board outlines
    .006,  #minimum real trace width; mainly used for text
    .008,  #mainly used for mid-sized text, not traces
    .010,  #minimum recommended trace width for low-current signals
    .012,
    .015,  #moderate low-voltage current
    .020,  #heavier trace for power, ground (even if a lighter one is adequate)
    .025,
    .030,  #heavy-current traces; be careful with these ones!
    .040,
    .050,
    .060,
    .080,
    .100,
    .120,
);
#Areas larger than the values below will be filled with parallel lines:
#This cuts down on the number of aperture sizes used.
#Set to 0 to always use an aperture or drill, regardless of size.
use constant { MAX_APERTURE => max((TOOL_SIZES)) + .004, MAX_DRILL => -min((TOOL_SIZES)) + .004 }; #max aperture and drill sizes (plus a little tolerance)
#DebugPrint(sprintf("using %d standard tool sizes: %s, max aper %.3f, max drill %.3f\n", scalar((TOOL_SIZES)), join(", ", (TOOL_SIZES)), MAX_APERTURE, MAX_DRILL), 1);

#NOTE: Compare the PDF to the original CAD file to check the accuracy of the PDF rendering and parsing!
#for example, the CAD software I used generated the following circles for holes:
#CAD hole size:   parsed PDF diameter:      error:
#  .014                .016                +.002
#  .020                .02267              +.00267
#  .025                .026                +.001
#  .029                .03167              +.00267
#  .033                .036                +.003
#  .040                .04267              +.00267
#This was usually ~ .002" - .003" too big compared to the hole as displayed in the CAD software.
#To compensate for PDF rendering errors (either during CAD Print function or PDF parsing logic), adjust the values below as needed.
#units are pixels; for example, a value of 2.4 at 600 dpi = .0004 inch, 2 at 600 dpi = .0033"
use constant
{
    HOLE_ADJUST => -0.004 * 600, #-2.6, #holes seemed to be slightly oversized (by .002" - .004"), so shrink them a little
    RNDPAD_ADJUST => -0.003 * 600, #-2, #-2.4, #round pads seemed to be slightly oversized, so shrink them a little
    SQRPAD_ADJUST => +0.001 * 600, #+.5, #square pads are sometimes too small by .00067, so bump them up a little
    RECTPAD_ADJUST => 0, #(pixels) rectangular pads seem to be okay? (not tested much)
    TRACE_ADJUST => 0, #(pixels) traces seemed to be okay?
    REDUCE_TOLERANCE => .001, #(inches) allow this much variation when reducing circles and rects
};

#Also, my CAD's Print function or the PDF print driver I used was a little off for circles, so define some additional adjustment values here:
#Values are added to X/Y coordinates; units are pixels; for example, a value of 1 at 600 dpi would be ~= .002 inch
use constant
{
    CIRCLE_ADJUST_MINX => 0,
    CIRCLE_ADJUST_MINY => -0.001 * 600, #-1, #circles were a little too high, so nudge them a little lower
    CIRCLE_ADJUST_MAXX => +0.001 * 600, #+1, #circles were a little too far to the left, so nudge them a little to the right
    CIRCLE_ADJUST_MAXY => 0,
    SUBST_CIRCLE_CLIPRECT => FALSE, #generate circle and substitute for clip rects (to compensate for the way some CAD software draws circles)
    WANT_CLIPRECT => TRUE, #FALSE, #AI doesn't need clip rect at all? should be on normally?
    RECT_COMPLETION => FALSE, #TRUE, #fill in 4th side of rect when 3 sides found
};

#allow .012 clearance around pads for solder mask:
#This value effectively adjusts pad sizes in the TOOL_SIZES list above (only for solder mask layers).
use constant SOLDER_MARGIN => +.012; #units are inches

#line join/cap styles:
use constant
{
    CAP_NONE => 0, #butt (none); line is exact length
    CAP_ROUND => 1, #round cap/join; line overhangs by a semi-circle at either end
    CAP_SQUARE => 2, #square cap/join; line overhangs by a half square on either end
    CAP_OVERRIDE => FALSE, #cap style overrides drawing logic
};
    
#number of elements in each shape type:
use constant
{
    RECT_SHAPELEN => 6, #x0, y0, x1, y1, count, "rect" (start, end corners)
    LINE_SHAPELEN => 6, #x0, y0, x1, y1, count, "line" (line seg)
    CURVE_SHAPELEN => 10, #xstart, ystart, x0, y0, x1, y1, xend, yend, count, "curve" (bezier 2 points)
    CIRCLE_SHAPELEN => 5, #x, y, 5, count, "circle" (center + radius)
};
#const my %SHAPELEN =
#Readonly my %SHAPELEN =>
our %SHAPELEN =
(
    rect => RECT_SHAPELEN,
    line => LINE_SHAPELEN,
    curve => CURVE_SHAPELEN,
    circle => CIRCLE_SHAPELEN,
);

#panelization:
#This will repeat the entire body the number of times indicated along the X or Y axes (files grow accordingly).
#Display elements that overhang PCB boundary can be squashed or left as-is (typically text or other silk screen markings).
#Set "overhangs" TRUE to allow overhangs, FALSE to truncate them.
#xpad and ypad allow margins to be added around outer edge of panelized PCB.
use constant PANELIZE => {'x' => 1, 'y' => 1, 'xpad' => 0, 'ypad' => 0, 'overhangs' => TRUE}; #number of times to repeat in X and Y directions

# Set this to 1 if you need TurboCAD support.
#$turboCAD = FALSE; #is this still needed as an option?

#CIRCAD pad generation uses an appropriate aperture, then moves it (stroke) "a little" - we use this to find pads and distinguish them from PCB holes. 
use constant PAD_STROKE => 0.3; #0.0005 * 600; #units are pixels
#convert very short traces to pads or holes:
use constant TRACE_MINLEN => .001; #units are inches
#use constant ALWAYS_XY => TRUE; #FALSE; #force XY even if X or Y doesn't change; NOTE: needs to be TRUE for all pads to show in FlatCAM and ViewPlot
use constant REMOVE_POLARITY => FALSE; #TRUE; #set to remove subtractive (negative) polarity; NOTE: must be FALSE for ground planes

#PDF uses "points", each point = 1/72 inch
#combined with a PDF scale factor of .12, this gives 600 dpi resolution (1/72 * .12 = 600 dpi)
use constant INCHES_PER_POINT => 1/72; #0.0138888889; #multiply point-size by this to get inches

# The precision used when computing a bezier curve. Higher numbers are more precise but slower (and generate larger files).
#$bezierPrecision = 100;
use constant BEZIER_PRECISION => 36; #100; #use const; reduced for faster rendering (mainly used for silk screen and thermal pads)

# Ground planes and silk screen or larger copper rectangles or circles are filled line-by-line using this resolution.
use constant FILL_WIDTH => .01; #fill at most 0.01 inch at a time

# The max number of characters to read into memory
use constant MAX_BYTES => 10 * M; #bumped up to 10 MB, use const

use constant DUP_DRILL1 => TRUE; #FALSE; #kludge: ViewPlot doesn't load drill files that are too small so duplicate first tool

my $runtime = time(); #Time::HiRes::gettimeofday(); #measure my execution time

print STDERR "Loaded config settings from '${\(__FILE__)}'.\n";
1; #last value must be truthful to indicate successful load


#############################################################################################
#junk/experiment:

#use Package::Constants;
#use Exporter qw(import); #https://perldoc.perl.org/Exporter.html

#my $caller = "pdf2gerb::";

#sub cfg
#{
#    my $proto = shift;
#    my $class = ref($proto) || $proto;
#    my $settings =
#    {
#        $WANT_DEBUG => 990, #10; #level of debug wanted; higher == more, lower == less, 0 == none
#    };
#    bless($settings, $class);
#    return $settings;
#}

#use constant HELLO => "hi there2"; #"main::HELLO" => "hi there";
#use constant GOODBYE => 14; #"main::GOODBYE" => 12;

#print STDERR "read cfg file\n";

#our @EXPORT_OK = Package::Constants->list(__PACKAGE__); #https://www.perlmonks.org/?node_id=1072691; NOTE: "_OK" skips short/common names

#print STDERR scalar(@EXPORT_OK) . " consts exported:\n";
#foreach(@EXPORT_OK) { print STDERR "$_\n"; }
#my $val = main::thing("xyz");
#print STDERR "caller gave me $val\n";
#foreach my $arg (@ARGV) { print STDERR "arg $arg\n"; }

Download Details:

Author: swannman
Source Code: https://github.com/swannman/pdf2gerb

License: GPL-3.0 license

#perl

Ahebwe Oscar

1620177818

Django admin full Customization step by step

Welcome to my blog , hey everyone in this article you learn how to customize the Django app and view in the article you will know how to register and unregister models from the admin view how to add filtering how to add a custom input field, and a button that triggers an action on all objects and even how to change the look of your app and page using the Django suit package let’s get started.

Database

Custom Titles of Django Admin

Exclude in Django Admin

Fields in Django Admin

#django #create super user django #customize django admin dashboard #django admin #django admin custom field display #django admin customization #django admin full customization #django admin interface #django admin register all models #django customization

I am Developer

1597489568

Dynamically Add/Remove Multiple input Fields and Submit to DB with jQuery and Laravel

In this post, i will show you how to dynamically add/remove multiple input fields and submit to database with jquery in php laravel framework. As well as, i will show you how to add/remove multiple input fields and submit to database with validation in laravel.

dynamically add remove multiple input fields and submit to database with jquery and laravel app will looks like, you can see in the following picture:

add/remove multiple input fields dynamically with jquery laravel

Laravel - Add/Remove Multiple Input Fields Using jQuery, javaScript

Follow the below given easy step to create dynamically add or remove multiple input fields and submit to database with jquery in php laravel

Step 1: Install Laravel App
Step 2: Add Database Details
Step 3: Create Migration & Model
Step 4: Add Routes
Step 5: Create Controller by Artisan
Step 6: Create Blade View
Step 7: Run Development Server

https://www.tutsmake.com/add-remove-multiple-input-fields-in-laravel-using-jquery/

#laravel - dynamically add or remove input fields using jquery #dynamically add / remove multiple input fields in laravel 7 using jquery ajax #add/remove multiple input fields dynamically with jquery laravel #dynamically add multiple input fields and submit to database with jquery and laravel #add remove input fields dynamically with jquery and submit to database #sql

Brook Legros

1659408900

TinyTDS: FreeTDS Bindings for Ruby using DB-Library

TinyTDS - Simple and fast FreeTDS bindings for Ruby using DB-Library.

- TravisCI
- Appveyor
- Gem Version
- Community

About TinyTDS

The TinyTDS gem is meant to serve the extremely common use-case of connecting, querying and iterating over results to Microsoft SQL Server or Sybase databases from Ruby using the FreeTDS's DB-Library API.

TinyTDS offers automatic casting to Ruby primitives along with proper encoding support. It converts all SQL Server datatypes to native Ruby primitives while supporting :utc or :local time zones for time-like types. To date it is the only Ruby client library that allows client encoding options, defaulting to UTF-8, while connecting to SQL Server. It also properly encodes all string and binary data. The motivation for TinyTDS is to become the de-facto low level connection mode for the SQL Server Adapter for ActiveRecord.

The API is simple and consists of these classes:

TinyTds::Client - Your connection to the database.
TinyTds::Result - Returned from issuing an #execute on the connection. It includes Enumerable.
TinyTds::Error - A wrapper for all FreeTDS exceptions.

Install

Installing with rubygems should just work. TinyTDS is currently tested on Ruby version 2.0.0 and upward.

$ gem install tiny_tds

If you use Windows, we pre-compile TinyTDS with static versions of FreeTDS and supporting libraries. If you're using RubyInstaller the binary gem will require that devkit is installed and in your path to operate properly.

On all other platforms, we will find these dependencies. It is recommended that you install the latest FreeTDS via your method of choice. For example, here is how to install FreeTDS on Ubuntu. You might also need the build-essential and possibly the libc6-dev packages.

$ apt-get install wget
$ apt-get install build-essential
$ apt-get install libc6-dev

$ wget http://www.freetds.org/files/stable/freetds-1.1.24.tar.gz
$ tar -xzf freetds-1.1.24.tar.gz
$ cd freetds-1.1.24
$ ./configure --prefix=/usr/local --with-tdsver=7.3
$ make
$ make install

Please read the MiniPortile and/or Windows sections at the end of this file for advanced configuration options past the following:

--with-freetds-dir=DIR
  Use the freetds library placed under DIR.

Getting Started

Optionally, Microsoft has done a great job writing some articles on how to get started with SQL Server and Ruby using TinyTDS. Please checkout one of the following posts that match your platform.

FreeTDS Compatibility & Configuration

TinyTDS is developed against FreeTDS 0.95, 0.99, and 1.0 current. Our default and recommended is 1.0. We also test with SQL Server 2008, 2014, and Azure. However, usage of TinyTDS with SQL Server 2000 or 2005 should be just fine. Below are a few QA style notes about installing FreeTDS.

NOTE: Windows users of our pre-compiled native gems need not worry about installing FreeTDS and its dependencies.

Do I need to install FreeTDS? Yes! Somehow, someway, you are going to need FreeTDS for TinyTDS to compile against.

OK, I am installing FreeTDS, how do I configure it? Contrary to what most people think, you do not need to specially configure FreeTDS in any way for client libraries like TinyTDS to use it. About the only requirement is that you compile it with libiconv for proper encoding support. FreeTDS must also be compiled with OpenSSL (or the like) to use it with Azure. See the "Using TinyTDS with Azure" section below for more info.

Do I need to configure --with-tdsver equal to anything? Most likely! Technically you should not have to. This is only a default for clients/configs that do not specify what TDS version they want to use. We are currently having issues with passing down a TDS version with the login bit. Till we get that fixed, if you are not using a freetds.conf or a TDSVER environment variable, then make sure to use 7.1.

But I want to use TDS version 7.2 for SQL Server 2005 and up! TinyTDS uses TDS version 7.1 (previously named 8.0) and fully supports all the data types supported by FreeTDS, this includes varchar(max) and nvarchar(max). Technically compiling and using TDS version 7.2 with FreeTDS is not supported. But this does not mean those data types will not work. I know, it's confusing If you want to learn more, read this thread. http://lists.ibiblio.org/pipermail/freetds/2011q3/027306.html

I want to configure FreeTDS using --enable-msdblib and/or --enable-sybase-compat so it works for my database. Cool? It's a waste of time and totally moot! Client libraries like TinyTDS define their own C structure names where they diverge from Sybase to SQL Server. Technically we use the MSDBLIB structures which does not mean we only work with that database vs Sybase. These configs are just a low level default for C libraries that do not define what they want. So I repeat, you do not NEED to use any of these, nor will they hurt anything since we control what C structure names we use internally!

Data Types

Our goal is to support every SQL Server data type and covert it to a logical Ruby object. When dates or times are returned, they are instantiated to either :utc or :local time depending on the query options. Only [datetimeoffset] types are excluded. All strings are associated the to the connection's encoding and all binary data types are associated to Ruby's ASCII-8BIT/BINARY encoding.

Below is a list of the data types we support when using the 7.3 TDS protocol version. Using a lower protocol version will result in these types being returned as strings.

[date]
[datetime2]
[datetimeoffset]
[time]

TinyTds::Client Usage

Connect to a database.

client = TinyTds::Client.new username: 'sa', password: 'secret', host: 'mydb.host.net'

Creating a new client takes a hash of options. For valid iconv encoding options, see the output of iconv -l. Only a few have been tested and highly recommended to leave blank for the UTF-8 default.

:username - The database server user.
:password - The user password.
:dataserver - Can be the name for your data server as defined in freetds.conf. Raw hostname or hostname:port will work here too. FreeTDS says that named instance like 'localhost\SQLEXPRESS' work too, but I highly suggest that you use the :host and :port options below. Google how to find your host port if you are using named instances or go here.
:host - Used if :dataserver blank. Can be an host name or IP.
:port - Defaults to 1433. Only used if :host is used.
:database - The default database to use.
:appname - Short string seen in SQL Servers process/activity window.
:tds_version - TDS version. Defaults to "7.3".
:login_timeout - Seconds to wait for login. Default to 60 seconds.
:timeout - Seconds to wait for a response to a SQL command. Default 5 seconds. Prior to 1.0rc5, FreeTDS was unable to set the timeout on a per-client basis, permitting only a global timeout value. This means that if you're using an older version, the timeout values for all clients will be overwritten each time you instantiate a new TinyTds::Client object. If you are using 1.0rc5 or later, all clients will have an independent timeout setting as you'd expect. Timeouts caused by network failure will raise a timeout error 1 second after the configured timeout limit is hit (see #481 for details).
:encoding - Any valid iconv value like CP1251 or ISO-8859-1. Default UTF-8.
:azure - Pass true to signal that you are connecting to azure.
:contained - Pass true to signal that you are connecting with a contained database user.
:use_utf16 - Instead of using UCS-2 for database wide character encoding use UTF-16. Newer Windows versions use this encoding instead of UCS-2. Default true.
:message_handler - Pass in a call-able object such as a Proc or a method to receive info messages from the database. It should have a single parameter, which will be a TinyTds::Error object representing the message. For example:

opts = ... # host, username, password, etc
opts[:message_handler] = Proc.new { |m| puts m.message }
client = TinyTds::Client.new opts
# => Changed database context to 'master'.
# => Changed language setting to us_english.
client.execute("print 'hello world!'").do
# => hello world!

Use the #active? method to determine if a connection is good. The implementation of this method may change but it should always guarantee that a connection is good. Current it checks for either a closed or dead connection.

client.dead?    # => false
client.closed?  # => false
client.active?  # => true
client.execute("SQL TO A DEAD SERVER")
client.dead?    # => true
client.closed?  # => false
client.active?  # => false
client.close
client.closed?  # => true
client.active?  # => false

Escape strings.

client.escape("How's It Going'") # => "How''s It Going''"

Send a SQL string to the database and return a TinyTds::Result object.

result = client.execute("SELECT * FROM [datatypes]")

TinyTds::Result Usage

A result object is returned by the client's execute command. It is important that you either return the data from the query, most likely with the #each method, or that you cancel the results before asking the client to execute another SQL batch. Failing to do so will yield an error.

Calling #each on the result will lazily load each row from the database.

result.each do |row|
  # By default each row is a hash.
  # The keys are the fields, as you'd expect.
  # The values are pre-built Ruby primitives mapped from their corresponding types.
end

A result object has a #fields accessor. It can be called before the result rows are iterated over. Even if no rows are returned, #fields will still return the column names you expected. Any SQL that does not return columned data will always return an empty array for #fields. It is important to remember that if you access the #fields before iterating over the results, the columns will always follow the default query option's :symbolize_keys setting at the client's level and will ignore the query options passed to each.

result = client.execute("USE [tinytdstest]")
result.fields # => []
result.do

result = client.execute("SELECT [id] FROM [datatypes]")
result.fields # => ["id"]
result.cancel
result = client.execute("SELECT [id] FROM [datatypes]")
result.each(:symbolize_keys => true)
result.fields # => [:id]

You can cancel a result object's data from being loading by the server.

result = client.execute("SELECT * FROM [super_big_table]")
result.cancel

You can use results cancelation in conjunction with results lazy loading, no problem.

result = client.execute("SELECT * FROM [super_big_table]")
result.each_with_index do |row, i|
  break if row > 10
end
result.cancel

If the SQL executed by the client returns affected rows, you can easily find out how many.

result.each
result.affected_rows # => 24

This pattern is so common for UPDATE and DELETE statements that the #do method cancels any need for loading the result data and returns the #affected_rows.

result = client.execute("DELETE FROM [datatypes]")
result.do # => 72

Likewise for INSERT statements, the #insert method cancels any need for loading the result data and executes a SCOPE_IDENTITY() for the primary key.

result = client.execute("INSERT INTO [datatypes] ([xml]) VALUES ('<html><br/></html>')")
result.insert # => 420

The result object can handle multiple result sets form batched SQL or stored procedures. It is critical to remember that when calling each with a block for the first time will return each "row" of each result set. Calling each a second time with a block will yield each "set".

sql = ["SELECT TOP (1) [id] FROM [datatypes]",
       "SELECT TOP (2) [bigint] FROM [datatypes] WHERE [bigint] IS NOT NULL"].join(' ')

set1, set2 = client.execute(sql).each
set1 # => [{"id"=>11}]
set2 # => [{"bigint"=>-9223372036854775807}, {"bigint"=>9223372036854775806}]

result = client.execute(sql)

result.each do |rowset|
  # First time data loading, yields each row from each set.
  # 1st: {"id"=>11}
  # 2nd: {"bigint"=>-9223372036854775807}
  # 3rd: {"bigint"=>9223372036854775806}
end

result.each do |rowset|
  # Second time over (if columns cached), yields each set.
  # 1st: [{"id"=>11}]
  # 2nd: [{"bigint"=>-9223372036854775807}, {"bigint"=>9223372036854775806}]
end

Use the #sqlsent? and #canceled? query methods on the client to determine if an active SQL batch still needs to be processed and or if data results were canceled from the last result object. These values reset to true and false respectively for the client at the start of each #execute and new result object. Or if all rows are processed normally, #sqlsent? will return false. To demonstrate, lets assume we have 100 rows in the result object.

client.sqlsent?   # = false
client.canceled?  # = false

result = client.execute("SELECT * FROM [super_big_table]")

client.sqlsent?   # = true
client.canceled?  # = false

result.each do |row|
  # Assume we break after 20 rows with 80 still pending.
  break if row["id"] > 20
end

client.sqlsent?   # = true
client.canceled?  # = false

result.cancel

client.sqlsent?   # = false
client.canceled?  # = true

It is possible to get the return code after executing a stored procedure from either the result or client object.

client.return_code  # => nil

result = client.execute("EXEC tinytds_TestReturnCodes")
result.do
result.return_code  # => 420
client.return_code  # => 420

Query Options

Every TinyTds::Result object can pass query options to the #each method. The defaults are defined and configurable by setting options in the TinyTds::Client.default_query_options hash. The default values are:

:as => :hash - Object for each row yielded. Can be set to :array.
:symbolize_keys => false - Row hash keys. Defaults to shared/frozen string keys.
:cache_rows => true - Successive calls to #each returns the cached rows.
:timezone => :local - Local to the Ruby client or :utc for UTC.
:empty_sets => true - Include empty results set in queries that return multiple result sets.

Each result gets a copy of the default options you specify at the client level and can be overridden by passing an options hash to the #each method. For example

result.each(:as => :array, :cache_rows => false) do |row|
  # Each row is now an array of values ordered by #fields.
  # Rows are yielded and forgotten about, freeing memory.
end

Besides the standard query options, the result object can take one additional option. Using :first => true will only load the first row of data and cancel all remaining results.

result = client.execute("SELECT * FROM [super_big_table]")
result.each(:first => true) # => [{'id' => 24}]

Row Caching

By default row caching is turned on because the SQL Server adapter for ActiveRecord would not work without it. I hope to find some time to create some performance patches for ActiveRecord that would allow it to take advantages of lazily created yielded rows from result objects. Currently only TinyTDS and the Mysql2 gem allow such a performance gain.

Encoding Error Handling

TinyTDS takes an opinionated stance on how we handle encoding errors. First, we treat errors differently on reads vs. writes. Our opinion is that if you are reading bad data due to your client's encoding option, you would rather just find ? marks in your strings vs being blocked with exceptions. This is how things wold work via ODBC or SMS. On the other hand, writes will raise an exception. In this case we raise the SYBEICONVO/2402 error message which has a description of Error converting characters into server's character set. Some character(s) could not be converted.. Even though the severity of this message is only a 4 and TinyTDS will automatically strip/ignore unknown characters, we feel you should know that you are inserting bad encodings. In this way, a transaction can be rolled back, etc. Remember, any database write that has bad characters due to the client encoding will still be written to the database, but it is up to you rollback said write if needed. Most ORMs like ActiveRecord handle this scenario just fine.

Timeout Error Handling

TinyTDS will raise a TinyTDS::Error when a timeout is reached based on the options supplied to the client. Depending on the reason for the timeout, the connection could be dead or alive. When db processing is the cause for the timeout, the connection should still be usable after the error is raised. When network failure is the cause of the timeout, the connection will be dead. If you attempt to execute another command batch on a dead connection you will see a DBPROCESS is dead or not enabled error. Therefore, it is recommended to check for a dead? connection before trying to execute another command batch.

Binstubs

The TinyTDS gem uses binstub wrappers which mirror compiled FreeTDS Utilities binaries. These native executables are usually installed at the system level when installing FreeTDS. However, when using MiniPortile to install TinyTDS as we do with Windows binaries, these binstubs will find and prefer local gem exe directory executables. These are the following binstubs we wrap.

tsql - Used to test connections and debug compile time settings.
defncopy - Used to dump schema structures.

Using TinyTDS With Rails & The ActiveRecord SQL Server adapter.

TinyTDS is the default connection mode for the SQL Server adapter in versions 3.1 or higher. The SQL Server adapter can be found using the links below.

ActiveRecord SQL Server Adapter: http://github.com/rails-sqlserver/activerecord-sqlserver-adapter

Using TinyTDS with Azure

TinyTDS is fully tested with the Azure platform. You must set the azure: true connection option when connecting. This is needed to specify the default database name in the login packet since Azure has no notion of USE [database]. FreeTDS must be compiled with OpenSSL too.

IMPORTANT: Do not use username@server.database.windows.net for the username connection option! You must use the shorter username@server instead!

Also, please read the Azure SQL Database General Guidelines and Limitations MSDN article to understand the differences. Specifically, the connection constraints section!

Connection Settings

A DBLIB connection does not have the same default SET options for a standard SMS SQL Server connection. Hence, we recommend the following options post establishing your connection.

SQL Server

SET ANSI_DEFAULTS ON

SET QUOTED_IDENTIFIER ON
SET CURSOR_CLOSE_ON_COMMIT OFF
SET IMPLICIT_TRANSACTIONS OFF
SET TEXTSIZE 2147483647
SET CONCAT_NULL_YIELDS_NULL ON

Azure

SET ANSI_NULLS ON
SET ANSI_NULL_DFLT_ON ON
SET ANSI_PADDING ON
SET ANSI_WARNINGS ON

SET QUOTED_IDENTIFIER ON
SET CURSOR_CLOSE_ON_COMMIT OFF
SET IMPLICIT_TRANSACTIONS OFF
SET TEXTSIZE 2147483647
SET CONCAT_NULL_YIELDS_NULL ON

Thread Safety

TinyTDS must be used with a connection pool for thread safety. If you use ActiveRecord or the Sequel gem this is done for you. However, if you are using TinyTDS on your own, we recommend using the ConnectionPool gem when using threads:

ConnectionPool Gem - https://github.com/mperham/connection_pool

Please read our thread_test.rb file for details on how we test its usage.

Emoji Support 😍

This is possible using FreeTDS version 0.95 or higher. You must use the use_utf16 login option or add the following config to your freetds.conf in either the global section or a specfic dataserver. If you are on Windows, the default location for your conf file will be in C:\Sites.

[global]
  use utf-16 = true

The default is true and since FreeTDS v1.0 would do this as well.

Compiling Gems for Windows

For the convenience of Windows users, TinyTDS ships pre-compiled gems for supported versions of Ruby on Windows. In order to generate these gems, rake-compiler-dock is used. This project provides several Docker images with rvm, cross-compilers and a number of different target versions of Ruby.

Run the following rake task to compile the gems for Windows. This will check the availability of Docker (and boot2docker on Windows or OS-X) and will give some advice for download and installation. When docker is running, it will download the docker image (once-only) and start the build:

$ rake gem:windows

The compiled gems will exist in ./pkg directory.

Development & Testing

First, clone the repo using the command line or your Git GUI of choice.

$ git clone git@github.com:rails-sqlserver/tiny_tds.git

After that, the quickest way to get setup for development is to use Docker. Assuming you have downloaded docker for your platform, you can use docker-compose to run the necessary containers for testing.

$ docker-compose up -d

This will download our SQL Server for Linux Docker image based from microsoft/mssql-server-linux/. Our image already has the [tinytdstest] DB and tinytds users created. This will also download a toxiproxy Docker image which we can use to simulate network failures for tests. Basically, it does the following.

$ docker network create main-network
$ docker pull metaskills/mssql-server-linux-tinytds
$ docker run -p 1433:1433 -d --name sqlserver --network main-network metaskills/mssql-server-linux-tinytds
$ docker pull shopify/toxiproxy
$ docker run -p 8474:8474 -p 1234:1234 -d --name toxiproxy --network main-network shopify/toxiproxy

If you are using your own database. Make sure to run these SQL commands as SA to get the test database and user installed.

CREATE DATABASE [tinytdstest];

CREATE LOGIN [tinytds] WITH PASSWORD = '', CHECK_POLICY = OFF, DEFAULT_DATABASE = [tinytdstest];
USE [tinytdstest];
CREATE USER [tinytds] FOR LOGIN [tinytds];
EXEC sp_addrolemember N'db_owner', N'tinytds';

From here you can build and run tests against an installed version of FreeTDS.

$ bundle install
$ bundle exec rake

Examples us using enviornment variables to customize the test task.

$ rake TINYTDS_UNIT_DATASERVER=mydbserver
$ rake TINYTDS_UNIT_DATASERVER=mydbserver TINYTDS_SCHEMA=sqlserver_2008
$ rake TINYTDS_UNIT_HOST=mydb.host.net TINYTDS_SCHEMA=sqlserver_azure
$ rake TINYTDS_UNIT_HOST=mydb.host.net TINYTDS_UNIT_PORT=5000 TINYTDS_SCHEMA=sybase_ase

Docker Builds

If you use a multi stage Docker build to assemble your gems in one phase and then copy your app and gems into another, lighter, container without build tools you will need to make sure you tell the OS how to find dependencies for TinyTDS.

After you have built and installed FreeTDS it will normally place library files in /usr/local/lib. When TinyTDS builds native extensions, it already knows to look here but if you copy your app to a new container that link will be broken.

Set the LD_LIBRARY_PATH environment variable export LD_LIBRARY_PATH=/usr/local/lib:${LD_LIBRARY_PATH} and run ldconfig. If you run ldd tiny_tds.so you should not see any broken links. Make sure you also copied in the library dependencies from your build container with a command like COPY --from=builder /usr/local/lib /usr/local/lib.

Help & Support

Github Source: http://github.com/rails-sqlserver/tiny_tds
Github Issues: http://github.com/rails-sqlserver/tiny_tds/issues
Gitter Chat: https://gitter.im/rails-sqlserver/activerecord-sqlserver-adapter
IRC Room: #rails-sqlserver on irc.freenode.net

About Me

My name is Ken Collins and I currently maintain the SQL Server adapter for ActiveRecord and wrote this library as my first cut into learning Ruby C extensions. Hopefully it will help promote the power of Ruby and the Rails framework to those that have not yet discovered it. My blog is metaskills.net and I can be found on twitter as @metaskills. Enjoy!

Special Thanks

Lars Kanis for all his help getting the Windows builds working again with rake-compiler-dock.
Erik Bryn for joining the project and helping me thru a few tight spots. - http://github.com/ebryn
To the authors and contributors of the Mysql2 gem for inspiration. - http://github.com/brianmario/mysql2
Yehuda Katz for articulating Ruby's need for proper encoding support. Especially in database drivers - http://yehudakatz.com/2010/05/05/ruby-1-9-encodings-a-primer-and-the-solution-for-rails/
Josh Clayton of Thoughtbot for writing about Ruby C extensions. - http://robots.thoughtbot.com/post/1037240922/get-your-c-on

License

TinyTDS is Copyright (c) 2010-2015 Ken Collins, ken@metaskills.net and Will Bond (Veracross LLC) wbond@breuer.com. It is distributed under the MIT license. Windows binaries contain pre-compiled versions of FreeTDS http://www.freetds.org/ which is licensed under the GNU LGPL license at http://www.gnu.org/licenses/lgpl-2.0.html

Author: rails-sqlserver
Source code: https://github.com/rails-sqlserver/tiny_tds
License:

#ruby #ruby-on-rails

Ahebwe Oscar

1620185280

How model queries work in Django

Welcome to my blog, hey everyone in this article we are going to be working with queries in Django so for any web app that you build your going to want to write a query so you can retrieve information from your database so in this article I’ll be showing you all the different ways that you can write queries and it should cover about 90% of the cases that you’ll have when you’re writing your code the other 10% depend on your specific use case you may have to get more complicated but for the most part what I cover in this article should be able to help you so let’s start with the model that I have I’ve already created it.

**Read More : **How to make Chatbot in Python.

let’s just get into this diagram that I made so in here:

django queries about Describe each parameter in Django querset

we’re making a simple query for the myModel table so we want to pull out all the information in the database so we have this variable which is gonna hold a return value and we have our myModel models so this is simply the myModel model name so whatever you named your model just make sure you specify that and we’re gonna access the objects attribute once we get that object’s attribute we can simply use the all method and this will return all the information in the database so we’re gonna start with all and then we will go into getting single items filtering that data and go to our command prompt.

Here and we’ll actually start making our queries from here to do this let’s just go ahead and run** Python manage.py shell** and I am in my project file so make sure you’re in there when you start and what this does is it gives us an interactive shell to actually start working with our data so this is a lot like the Python shell but because we did manage.py it allows us to do things a Django way and actually query our database now open up the command prompt and let’s go ahead and start making our first queries.

#django #django model queries #django orm #django queries #django query #model django query #model query #query with django