Royce  Reinger

Royce Reinger

1646475660

Python-hunter: Hunter Is A Flexible Code Tracing toolkit

Hunter is a flexible code tracing toolkit, not for measuring coverage, but for debugging, logging, inspection and other nefarious purposes. It has a simple Python API, a convenient terminal API and a CLI tool to attach to processes.

Installation

pip install hunter

Documentation

https://python-hunter.readthedocs.io/

Overview

Basic use involves passing various filters to the trace option. An example:

import hunter
hunter.trace(module='posixpath', action=hunter.CallPrinter)

import os
os.path.join('a', 'b')

That would result in:

>>> os.path.join('a', 'b')
         /usr/lib/python3.6/posixpath.py:75    call      => join(a='a')
         /usr/lib/python3.6/posixpath.py:80    line         a = os.fspath(a)
         /usr/lib/python3.6/posixpath.py:81    line         sep = _get_sep(a)
         /usr/lib/python3.6/posixpath.py:41    call         => _get_sep(path='a')
         /usr/lib/python3.6/posixpath.py:42    line            if isinstance(path, bytes):
         /usr/lib/python3.6/posixpath.py:45    line            return '/'
         /usr/lib/python3.6/posixpath.py:45    return       <= _get_sep: '/'
         /usr/lib/python3.6/posixpath.py:82    line         path = a
         /usr/lib/python3.6/posixpath.py:83    line         try:
         /usr/lib/python3.6/posixpath.py:84    line         if not p:
         /usr/lib/python3.6/posixpath.py:86    line         for b in map(os.fspath, p):
         /usr/lib/python3.6/posixpath.py:87    line         if b.startswith(sep):
         /usr/lib/python3.6/posixpath.py:89    line         elif not path or path.endswith(sep):
         /usr/lib/python3.6/posixpath.py:92    line         path += sep + b
         /usr/lib/python3.6/posixpath.py:86    line         for b in map(os.fspath, p):
         /usr/lib/python3.6/posixpath.py:96    line         return path
         /usr/lib/python3.6/posixpath.py:96    return    <= join: 'a/b'
'a/b'

In a terminal it would look like:

https://raw.githubusercontent.com/ionelmc/python-hunter/master/docs/code-trace.png

Another useful scenario is to ignore all standard modules and force colors to make them stay even if the output is redirected to a file.

import hunter
hunter.trace(stdlib=False, action=hunter.CallPrinter(force_colors=True))

Actions

Output format can be controlled with "actions". There's an alternative CodePrinter action that doesn't handle nesting (it was the default action until Hunter 2.0).

If filters match then action will be run. Example:

import hunter
hunter.trace(module='posixpath', action=hunter.CodePrinter)

import os
os.path.join('a', 'b')

That would result in:

>>> os.path.join('a', 'b')
         /usr/lib/python3.6/posixpath.py:75    call      def join(a, *p):
         /usr/lib/python3.6/posixpath.py:80    line          a = os.fspath(a)
         /usr/lib/python3.6/posixpath.py:81    line          sep = _get_sep(a)
         /usr/lib/python3.6/posixpath.py:41    call      def _get_sep(path):
         /usr/lib/python3.6/posixpath.py:42    line          if isinstance(path, bytes):
         /usr/lib/python3.6/posixpath.py:45    line              return '/'
         /usr/lib/python3.6/posixpath.py:45    return            return '/'
                                               ...       return value: '/'
         /usr/lib/python3.6/posixpath.py:82    line          path = a
         /usr/lib/python3.6/posixpath.py:83    line          try:
         /usr/lib/python3.6/posixpath.py:84    line              if not p:
         /usr/lib/python3.6/posixpath.py:86    line              for b in map(os.fspath, p):
         /usr/lib/python3.6/posixpath.py:87    line                  if b.startswith(sep):
         /usr/lib/python3.6/posixpath.py:89    line                  elif not path or path.endswith(sep):
         /usr/lib/python3.6/posixpath.py:92    line                      path += sep + b
         /usr/lib/python3.6/posixpath.py:86    line              for b in map(os.fspath, p):
         /usr/lib/python3.6/posixpath.py:96    line          return path
         /usr/lib/python3.6/posixpath.py:96    return        return path
                                               ...       return value: 'a/b'
'a/b'
  • or in a terminal:

https://raw.githubusercontent.com/ionelmc/python-hunter/master/docs/simple-trace.png


Another useful action is the VarsPrinter:

import hunter
# note that this kind of invocation will also use the default `CallPrinter` action
hunter.trace(hunter.Q(module='posixpath', action=hunter.VarsPrinter('path')))

import os
os.path.join('a', 'b')

That would result in:

>>> os.path.join('a', 'b')
     /usr/lib/python3.6/posixpath.py:75    call      => join(a='a')
     /usr/lib/python3.6/posixpath.py:80    line         a = os.fspath(a)
     /usr/lib/python3.6/posixpath.py:81    line         sep = _get_sep(a)
     /usr/lib/python3.6/posixpath.py:41    call      [path => 'a']
     /usr/lib/python3.6/posixpath.py:41    call         => _get_sep(path='a')
     /usr/lib/python3.6/posixpath.py:42    line      [path => 'a']
     /usr/lib/python3.6/posixpath.py:42    line            if isinstance(path, bytes):
     /usr/lib/python3.6/posixpath.py:45    line      [path => 'a']
     /usr/lib/python3.6/posixpath.py:45    line            return '/'
     /usr/lib/python3.6/posixpath.py:45    return    [path => 'a']
     /usr/lib/python3.6/posixpath.py:45    return       <= _get_sep: '/'
     /usr/lib/python3.6/posixpath.py:82    line         path = a
     /usr/lib/python3.6/posixpath.py:83    line      [path => 'a']
     /usr/lib/python3.6/posixpath.py:83    line         try:
     /usr/lib/python3.6/posixpath.py:84    line      [path => 'a']
     /usr/lib/python3.6/posixpath.py:84    line         if not p:
     /usr/lib/python3.6/posixpath.py:86    line      [path => 'a']
     /usr/lib/python3.6/posixpath.py:86    line         for b in map(os.fspath, p):
     /usr/lib/python3.6/posixpath.py:87    line      [path => 'a']
     /usr/lib/python3.6/posixpath.py:87    line         if b.startswith(sep):
     /usr/lib/python3.6/posixpath.py:89    line      [path => 'a']
     /usr/lib/python3.6/posixpath.py:89    line         elif not path or path.endswith(sep):
     /usr/lib/python3.6/posixpath.py:92    line      [path => 'a']
     /usr/lib/python3.6/posixpath.py:92    line         path += sep + b
     /usr/lib/python3.6/posixpath.py:86    line      [path => 'a/b']
     /usr/lib/python3.6/posixpath.py:86    line         for b in map(os.fspath, p):
     /usr/lib/python3.6/posixpath.py:96    line      [path => 'a/b']
     /usr/lib/python3.6/posixpath.py:96    line         return path
     /usr/lib/python3.6/posixpath.py:96    return    [path => 'a/b']
     /usr/lib/python3.6/posixpath.py:96    return    <= join: 'a/b'
'a/b'

In a terminal it would look like:

https://raw.githubusercontent.com/ionelmc/python-hunter/master/docs/vars-trace.png


You can give it a tree-like configuration where you can optionally configure specific actions for parts of the tree (like dumping variables or a pdb set_trace):

from hunter import trace, Q, Debugger
from pdb import Pdb

trace(
    # drop into a Pdb session if ``foo.bar()`` is called
    Q(module="foo", function="bar", kind="call", action=Debugger(klass=Pdb))
    |  # or
    Q(
        # show code that contains "mumbo.jumbo" on the current line
        lambda event: event.locals.get("mumbo") == "jumbo",
        # and it's not in Python's stdlib
        stdlib=False,
        # and it contains "mumbo" on the current line
        source__contains="mumbo"
    )
)

import foo
foo.func()

With a foo.py like this:

def bar():
    execution_will_get_stopped  # cause we get a Pdb session here

def func():
    mumbo = 1
    mumbo = "jumbo"
    print("not shown in trace")
    print(mumbo)
    mumbo = 2
    print(mumbo) # not shown in trace
    bar()

We get:

>>> foo.func()
not shown in trace
    /home/ionel/osp/python-hunter/foo.py:8     line          print(mumbo)
jumbo
    /home/ionel/osp/python-hunter/foo.py:9     line          mumbo = 2
2
    /home/ionel/osp/python-hunter/foo.py:1     call      def bar():
> /home/ionel/osp/python-hunter/foo.py(2)bar()
-> execution_will_get_stopped  # cause we get a Pdb session here
(Pdb)

In a terminal it would look like:

https://raw.githubusercontent.com/ionelmc/python-hunter/master/docs/tree-trace.png

Tracing processes

In similar fashion to strace Hunter can trace other processes, eg:

hunter-trace --gdb -p 123

If you wanna play it safe (no messy GDB) then add this in your code:

from hunter import remote
remote.install()

Then you can do:

hunter-trace -p 123

See docs on the remote feature.

Note: Windows ain't supported.

Environment variable activation

For your convenience environment variable activation is available. Just run your app like this:

PYTHONHUNTER="module='os.path'" python yourapp.py

On Windows you'd do something like:

set PYTHONHUNTER=module='os.path'
python yourapp.py

The activation works with a clever .pth file that checks for that env var presence and before your app runs does something like this:

from hunter import *
trace(<whatever-you-had-in-the-PYTHONHUNTER-env-var>)

Note that Hunter is activated even if the env var is empty, eg: PYTHONHUNTER="".

Environment variable configuration

Sometimes you always use the same options (like stdlib=False or force_colors=True). To save typing you can set something like this in your environment:

PYTHONHUNTERCONFIG="stdlib=False,force_colors=True"

This is the same as PYTHONHUNTER="stdlib=False,action=CallPrinter(force_colors=True)".

Notes:

Setting PYTHONHUNTERCONFIG alone doesn't activate hunter.

All the options for the builtin actions are supported.

Although using predicates is supported it can be problematic. Example of setup that won't trace anything:

PYTHONHUNTERCONFIG="Q(module_startswith='django')"
PYTHONHUNTER="Q(module_startswith='celery')"

which is the equivalent of:

PYTHONHUNTER="Q(module_startswith='django'),Q(module_startswith='celery')"

which is the equivalent of:

PYTHONHUNTER="Q(module_startswith='django')&Q(module_startswith='celery')"

Filtering DSL

Hunter supports a flexible query DSL, see the introduction.

Development

To run the all tests run:

tox

Design notes

Hunter doesn't do everything. As a design goal of this library some things are made intentionally austere and verbose (to avoid complexity, confusion and inconsistency). This has few consequences:

  • There are Operators but there's no negation operator. Instead you're expected to negate a Query object, eg: ~Q(module='re').
  • There are no specialized operators or filters - all filters behave exactly the same. For example:
    • No filter for packages. You're expected to filter by module with an operator.
    • No filter for arguments, return values or variables. You're expected to write your own filter function and deal with the problems of poking into objects.
  • Layering is minimal. There's are some helpers that do some argument processing and conversions to save you some typing but that's about it.
  • The library doesn't try to hide the mechanics of tracing in Python - it's 1:1 regarding what Python sends to a trace function if you'd be using sys.settrace.
  • Doesn't have any storage. You are expected to redirect output to a file.

You should look at it like it's a tool to help you understand and debug big applications, or a framework ridding you of the boring parts of settrace, not something that helps you learn Python.

FAQ

Why not Smiley?

There's some obvious overlap with smiley but there are few fundamental differences:

Complexity. Smiley is simply over-engineered:

  • It uses IPC and a SQL database.
  • It has a webserver. Lots of dependencies.
  • It uses threads. Side-effects and subtle bugs are introduced in your code.
  • It records everything. Tries to dump any variable. Often fails and stops working.

Tracing long running code. This will make Smiley record lots of data, making it unusable.

Now because Smiley records everything, you'd think it's better suited for short programs. But alas, if your program runs quickly then it's pointless to record the execution. You can just run it again.

It seems there's only one situation where it's reasonable to use Smiley: tracing io-bound apps remotely. Those apps don't execute lots of code, they just wait on network so Smiley's storage won't blow out of proportion and tracing overhead might be acceptable.

Use-cases. It seems to me Smiley's purpose is not really debugging code, but more of a "non interactive monitoring" tool.

In contrast, Hunter is very simple:

Few dependencies.

Low overhead (tracing/filtering code has an optional Cython extension).

No storage. This simplifies lots of things.

The only cost is that you might need to run the code multiple times to get the filtering/actions right. This means Hunter is not really suited for "post-mortem" debugging. If you can't reproduce the problem anymore then Hunter won't be of much help.

Why not pytrace?

Pytrace is another tracer tool. It seems quite similar to Smiley - it uses a sqlite database for the events, threads and IPC, thus it's reasonable to expect the same kind of problems.

Why not PySnooper or snoop?

snoop is a refined version of PySnooper. Both are more suited to tracing small programs or functions as the output is more verbose and less suited to the needs of tracing a big application where Hunter provides more flexible setup, filtering capabilities, speed and brevity.

Why not coverage?

For purposes of debugging coverage is a great tool but only as far as "debugging by looking at what code is (not) run". Checking branch coverage is good but it will only get you as far.

From the other perspective, you'd be wondering if you could use Hunter to measure coverage-like things. You could do it but for that purpose Hunter is very "rough": it has no builtin storage. You'd have to implement your own storage. You can do it but it wouldn't give you any advantage over making your own tracer if you don't need to "pre-filter" whatever you're recording.

In other words, filtering events is the main selling point of Hunter - it's fast (cython implementation) and the query API is flexible enough.

Projects using Hunter

Noteworthy usages or Hunter (submit a PR with your project if you built a tool that relies on hunter):

More projects using it at https://github.com/ionelmc/python-hunter/network/dependents

Author: Ionelmc
Source Code: https://github.com/ionelmc/python-hunter 
License: BSD-2-Clause License

#python #debugging 

What is GEEK

Buddha Community

Python-hunter: Hunter Is A Flexible Code Tracing toolkit
Monty  Boehm

Monty Boehm

1675304280

How to Use Hotwire Rails

Introduction

We are back with another exciting and much-talked-about Rails tutorial on how to use Hotwire with the Rails application. This Hotwire Rails tutorial is an alternate method for building modern web applications that consume a pinch of JavaScript.

Rails 7 Hotwire is the default front-end framework shipped with Rails 7 after it was launched. It is used to represent HTML over the wire in the Rails application. Previously, we used to add a hotwire-rails gem in our gem file and then run rails hotwire: install. However, with the introduction of Rails 7, the gem got deprecated. Now, we use turbo-rails and stimulus rails directly, which work as Hotwire’s SPA-like page accelerator and Hotwire’s modest JavaScript framework.

What is Hotwire?

Hotwire is a package of different frameworks that help to build applications. It simplifies the developer’s work for writing web pages without the need to write JavaScript, and instead sending HTML code over the wire.

Introduction to The Hotwire Framework:

1. Turbo:

It uses simplified techniques to build web applications while decreasing the usage of JavaScript in the application. Turbo offers numerous handling methods for the HTML data sent over the wire and displaying the application’s data without actually loading the entire page. It helps to maintain the simplicity of web applications without destroying the single-page application experience by using the below techniques:

Turbo Frames: Turbo Frames help to load the different sections of our markup without any dependency as it divides the page into different contexts separately called frames and updates these frames individually.
Turbo Drive: Every link doesn’t have to make the entire page reload when clicked. Only the HTML contained within the tag will be displayed.
Turbo Streams: To add real-time features to the application, this technique is used. It helps to bring real-time data to the application using CRUD actions.

2. Stimulus

It represents the JavaScript framework, which is required when JS is a requirement in the application. The interaction with the HTML is possible with the help of a stimulus, as the controllers that help those interactions are written by a stimulus.

3. Strada

Not much information is available about Strada as it has not been officially released yet. However, it works with native applications, and by using HTML bridge attributes, interaction is made possible between web applications and native apps.

Simple diagrammatic representation of Hotwire Stack:

Hotwire Stack

Prerequisites For Hotwire Rails Tutorial

As we are implementing the Ruby on Rails Hotwire tutorial, make sure about the following installations before you can get started.

  • Ruby on Rails
  • Hotwire gem
  • PostgreSQL/SQLite (choose any one database)
  • Turbo Rails
  • Stimulus.js

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Contact Bacancy today and hire Ruby developers to start building your dream project!

Create a new Rails Project

Find the following commands to create a rails application.

mkdir ~/projects/railshotwire
cd ~/projects/railshotwire
echo "source 'https://rubygems.org'" > Gemfile
echo "gem 'rails', '~> 7.0.0'" >> Gemfile
bundle install  
bundle exec rails new . --force -d=postgresql

Now create some files for the project, up till now no usage of Rails Hotwire can be seen.
Fire the following command in your terminal.

  • For creating a default controller for the application
echo "class HomeController < ApplicationController" > app/controllers/home_controller.rb
echo "end" >> app/controllers/home_controller.rb
  • For creating another controller for the application
echo "class OtherController < ApplicationController" > app/controllers/other_controller.rb
echo "end" >> app/controllers/home_controller.rb
  • For creating routes for the application
echo "Rails.application.routes.draw do" > config/routes.rb
echo '  get "home/index"' >> config/routes.rb
echo '  get "other/index"' >> config/routes.rb
echo '  root to: "home#index"' >> config/routes.rb
echo 'end' >> config/routes.rb
  • For creating a default view for the application
mkdir app/views/home
echo '<h1>This is Rails Hotwire homepage</h1>' > app/views/home/index.html.erb
echo '<div><%= link_to "Enter to other page", other_index_path %></div>' >> app/views/home/index.html.erb
  • For creating another view for the application
mkdir app/views/other
echo '<h1>This is Another page</h1>' > app/views/other/index.html.erb
echo '<div><%= link_to "Enter to home page", root_path %></div>' >> app/views/other/index.html.erb
  • For creating a database and schema.rb file for the application
bin/rails db:create
bin/rails db:migrate
  • For checking the application run bin/rails s and open your browser, your running application will have the below view.

Rails Hotwire Home Page

Additionally, you can clone the code and browse through the project. Here’s the source code of the repository: Rails 7 Hotwire application

Now, let’s see how Hotwire Rails can work its magic with various Turbo techniques.

Hotwire Rails: Turbo Drive

Go to your localhost:3000 on your web browser and right-click on the Inspect and open a Network tab of the DevTools of the browser.

Now click on go to another page link that appears on the home page to redirect from the home page to another page. In our Network tab, we can see that this action of navigation is achieved via XHR. It appears only the part inside HTML is reloaded, here neither the CSS is reloaded nor the JS is reloaded when the navigation action is performed.

Hotwire Rails Turbo Drive

By performing this action we can see that Turbo Drive helps to represent the HTML response without loading the full page and only follows redirect and reindeer HTML responses which helps to make the application faster to access.

Hotwire Rails: Turbo Frame

This technique helps to divide the current page into different sections called frames that can be updated separately independently when new data is added from the server.
Below we discuss the different use cases of Turbo frame like inline edition, sorting, searching, and filtering of data.

Let’s perform some practical actions to see the example of these use cases.

Make changes in the app/controllers/home_controller.rb file

#CODE

class HomeController < ApplicationController
   def turbo_frame_form
   end
   
   def turbo_frame submit
      extracted_anynumber = params[:any][:anynumber]
      render :turbo_frame_form, status: :ok, locals: {anynumber: extracted_anynumber,      comment: 'turbo_frame_submit ok' }
   end
end

Turbo Frame

Add app/views/home/turbo_frame_form.html.erb file to the application and add this content inside the file.

#CODE

<section>

    <%= turbo_frame_tag 'anyframe' do %>
            
      <div>
          <h2>Frame view</h2>
          <%= form_with scope: :any, url: turbo_frame_submit_path, local: true do |form| %>
              <%= form.label :anynumber, 'Type an integer (odd or even)', 'class' => 'my-0  d-inline'  %>
              <%= form.text_field :anynumber, type: 'number', 'required' => 'true', 'value' => "#{local_assigns[:anynumber] || 0}",  'aria-describedby' => 'anynumber' %>
              <%= form.submit 'Submit this number', 'id' => 'submit-number' %>
          <% end %>
      </div>
      <div>
        <h2>Data of the view</h2>
        <pre style="font-size: .7rem;"><%= JSON.pretty_generate(local_assigns) %></pre> 
      </div>
      
    <% end %>

</section>

Add the content inside file

Make some adjustments in routes.rb

#CODE

Rails.application.routes.draw do
  get 'home/index'
  get 'other/index'

  get '/home/turbo_frame_form' => 'home#turbo_frame_form', as: 'turbo_frame_form'
  post '/home/turbo_frame_submit' => 'home#turbo_frame_submit', as: 'turbo_frame_submit'


  root to: "home#index"
end
  • Next step is to change homepage view in app/views/home/index.html.erb

#CODE

<h1>This is Rails Hotwire home page</h1>
<div><%= link_to "Enter to other page", other_index_path %></div>

<%= turbo_frame_tag 'anyframe' do %>        
  <div>
      <h2>Home view</h2>
      <%= form_with scope: :any, url: turbo_frame_submit_path, local: true do |form| %>
          <%= form.label :anynumber, 'Type an integer (odd or even)', 'class' => 'my-0  d-inline'  %>
          <%= form.text_field :anynumber, type: 'number', 'required' => 'true', 'value' => "#{local_assigns[:anynumber] || 0}",  'aria-describedby' => 'anynumber' %>
          <%= form.submit 'Submit this number', 'id' => 'submit-number' %>
      <% end %>
  <div>
<% end %>

Change HomePage

After making all the changes, restart the rails server and refresh the browser, the default view will appear on the browser.

restart the rails serverNow in the field enter any digit, after entering the digit click on submit button, and as the submit button is clicked we can see the Turbo Frame in action in the below screen, we can observe that the frame part changed, the first title and first link didn’t move.

submit button is clicked

Hotwire Rails: Turbo Streams

Turbo Streams deliver page updates over WebSocket, SSE or in response to form submissions by only using HTML and a series of CRUD-like operations, you are free to say that either

  • Update the piece of HTML while responding to all the other actions like the post, put, patch, and delete except the GET action.
  • Transmit a change to all users, without reloading the browser page.

This transmit can be represented by a simple example.

  • Make changes in app/controllers/other_controller.rb file of rails application

#CODE

class OtherController < ApplicationController

  def post_something
    respond_to do |format|
      format.turbo_stream {  }
    end
  end

   end

file of rails application

Add the below line in routes.rb file of the application

#CODE

post '/other/post_something' => 'other#post_something', as: 'post_something'
Add the below line

Superb! Rails will now attempt to locate the app/views/other/post_something.turbo_stream.erb template at any moment the ‘/other/post_something’ endpoint is reached.

For this, we need to add app/views/other/post_something.turbo_stream.erb template in the rails application.

#CODE

<turbo-stream action="append" target="messages">
  <template>
    <div id="message_1">This changes the existing message!</div>
  </template>
</turbo-stream>
Add template in the rails application

This states that the response will try to append the template of the turbo frame with ID “messages”.

Now change the index.html.erb file in app/views/other paths with the below content.

#CODE

<h1>This is Another page</h1>
<div><%= link_to "Enter to home page", root_path %></div>

<div style="margin-top: 3rem;">
  <%= form_with scope: :any, url: post_something_path do |form| %>
      <%= form.submit 'Post any message %>
  <% end %>
  <turbo-frame id="messages">
    <div>An empty message</div>
  </turbo-frame>
</div>
change the index.html.erb file
  • After making all the changes, restart the rails server and refresh the browser, and go to the other page.

go to the other page

  • Once the above screen appears, click on the Post any message button

Post any message button

This action shows that after submitting the response, the Turbo Streams help the developer to append the message, without reloading the page.

Another use case we can test is that rather than appending the message, the developer replaces the message. For that, we need to change the content of app/views/other/post_something.turbo_stream.erb template file and change the value of the action attribute from append to replace and check the changes in the browser.

#CODE

<turbo-stream action="replace" target="messages">
  <template>
    <div id="message_1">This changes the existing message!</div>
  </template>
</turbo-stream>

change the value of the action attributeWhen we click on Post any message button, the message that appear below that button will get replaced with the message that is mentioned in the app/views/other/post_something.turbo_stream.erb template

click on Post any message button

Stimulus

There are some cases in an application where JS is needed, therefore to cover those scenarios we require Hotwire JS tool. Hotwire has a JS tool because in some scenarios Turbo-* tools are not sufficient. But as we know that Hotwire is used to reduce the usage of JS in an application, Stimulus considers HTML as the single source of truth. Consider the case where we have to give elements on a page some JavaScript attributes, such as data controller, data-action, and data target. For that, a stimulus controller that can access elements and receive events based on those characteristics will be created.

Make a change in app/views/other/index.html.erb template file in rails application

#CODE

<h1>This is Another page</h1>
<div><%= link_to "Enter to home page", root_path %></div>

<div style="margin-top: 2rem;">
  <%= form_with scope: :any, url: post_something_path do |form| %>
      <%= form.submit 'Post something' %>
  <% end %>
  <turbo-frame id="messages">
    <div>An empty message</div>
  </turbo-frame>
</div>

<div style="margin-top: 2rem;">
  <h2>Stimulus</h2>  
  <div data-controller="hello">
    <input data-hello-target="name" type="text">
    <button data-action="click->hello#greet">
      Greet
    </button>
    <span data-hello-target="output">
    </span>
  </div>
</div>

Make A changeMake changes in the hello_controller.js in path app/JavaScript/controllers and add a stimulus controller in the file, which helps to bring the HTML into life.

#CODE

import { Controller } from "@hotwired/stimulus"

export default class extends Controller {
  static targets = [ "name", "output" ]

  greet() {
    this.outputTarget.textContent =
      `Hello, ${this.nameTarget.value}!`
  }
}

add a stimulus controller in the fileGo to your browser after making the changes in the code and click on Enter to other page link which will navigate to the localhost:3000/other/index page there you can see the changes implemented by the stimulus controller that is designed to augment your HTML with just enough behavior to make it more responsive.

With just a little bit of work, Turbo and Stimulus together offer a complete answer for applications that are quick and compelling.

Using Rails 7 Hotwire helps to load the pages at a faster speed and allows you to render templates on the server, where you have access to your whole domain model. It is a productive development experience in ROR, without compromising any of the speed or responsiveness associated with SPA.

Conclusion

We hope you were satisfied with our Rails Hotwire tutorial. Write to us at service@bacancy.com for any query that you want to resolve, or if you want us to share a tutorial on your query.

For more such solutions on RoR, check out our Ruby on Rails Tutorials. We will always strive to amaze you and cater to your needs.

Original article source at: https://www.bacancytechnology.com/

#rails #ruby 

Ray  Patel

Ray Patel

1619510796

Lambda, Map, Filter functions in python

Welcome to my Blog, In this article, we will learn python lambda function, Map function, and filter function.

Lambda function in python: Lambda is a one line anonymous function and lambda takes any number of arguments but can only have one expression and python lambda syntax is

Syntax: x = lambda arguments : expression

Now i will show you some python lambda function examples:

#python #anonymous function python #filter function in python #lambda #lambda python 3 #map python #python filter #python filter lambda #python lambda #python lambda examples #python map

Shardul Bhatt

Shardul Bhatt

1626775355

Why use Python for Software Development

No programming language is pretty much as diverse as Python. It enables building cutting edge applications effortlessly. Developers are as yet investigating the full capability of end-to-end Python development services in various areas. 

By areas, we mean FinTech, HealthTech, InsureTech, Cybersecurity, and that's just the beginning. These are New Economy areas, and Python has the ability to serve every one of them. The vast majority of them require massive computational abilities. Python's code is dynamic and powerful - equipped for taking care of the heavy traffic and substantial algorithmic capacities. 

Programming advancement is multidimensional today. Endeavor programming requires an intelligent application with AI and ML capacities. Shopper based applications require information examination to convey a superior client experience. Netflix, Trello, and Amazon are genuine instances of such applications. Python assists with building them effortlessly. 

5 Reasons to Utilize Python for Programming Web Apps 

Python can do such numerous things that developers can't discover enough reasons to admire it. Python application development isn't restricted to web and enterprise applications. It is exceptionally adaptable and superb for a wide range of uses.

Robust frameworks 

Python is known for its tools and frameworks. There's a structure for everything. Django is helpful for building web applications, venture applications, logical applications, and mathematical processing. Flask is another web improvement framework with no conditions. 

Web2Py, CherryPy, and Falcon offer incredible capabilities to customize Python development services. A large portion of them are open-source frameworks that allow quick turn of events. 

Simple to read and compose 

Python has an improved sentence structure - one that is like the English language. New engineers for Python can undoubtedly understand where they stand in the development process. The simplicity of composing allows quick application building. 

The motivation behind building Python, as said by its maker Guido Van Rossum, was to empower even beginner engineers to comprehend the programming language. The simple coding likewise permits developers to roll out speedy improvements without getting confused by pointless subtleties. 

Utilized by the best 

Alright - Python isn't simply one more programming language. It should have something, which is the reason the business giants use it. Furthermore, that too for different purposes. Developers at Google use Python to assemble framework organization systems, parallel information pusher, code audit, testing and QA, and substantially more. Netflix utilizes Python web development services for its recommendation algorithm and media player. 

Massive community support 

Python has a steadily developing community that offers enormous help. From amateurs to specialists, there's everybody. There are a lot of instructional exercises, documentation, and guides accessible for Python web development solutions. 

Today, numerous universities start with Python, adding to the quantity of individuals in the community. Frequently, Python designers team up on various tasks and help each other with algorithmic, utilitarian, and application critical thinking. 

Progressive applications 

Python is the greatest supporter of data science, Machine Learning, and Artificial Intelligence at any enterprise software development company. Its utilization cases in cutting edge applications are the most compelling motivation for its prosperity. Python is the second most well known tool after R for data analytics.

The simplicity of getting sorted out, overseeing, and visualizing information through unique libraries makes it ideal for data based applications. TensorFlow for neural networks and OpenCV for computer vision are two of Python's most well known use cases for Machine learning applications.

Summary

Thinking about the advances in programming and innovation, Python is a YES for an assorted scope of utilizations. Game development, web application development services, GUI advancement, ML and AI improvement, Enterprise and customer applications - every one of them uses Python to its full potential. 

The disadvantages of Python web improvement arrangements are regularly disregarded by developers and organizations because of the advantages it gives. They focus on quality over speed and performance over blunders. That is the reason it's a good idea to utilize Python for building the applications of the future.

#python development services #python development company #python app development #python development #python in web development #python software development

Ray  Patel

Ray Patel

1623077340

50+ Basic Python Code Examples

List, strings, score calculation and more…

1. How to print “Hello World” on Python?

2. How to print “Hello + Username” with the user’s name on Python?

3. How to add 2 numbers entered on Python?

4. How to find the Average of 2 Entered Numbers on Python?

5. How to calculate the Entered Visa and Final Grade Average on Python?

6. How to find the Average of 3 Written Grades entered on Python?

7. How to show the Class Pass Status (PASSED — FAILED) of the Student whose Written Average Has Been Entered on Python?

8. How to find out if the entered number is odd or even on Python?

9. How to find out if the entered number is Positive, Negative, or 0 on Python?

#programming #python #coding #50+ basic python code examples #python programming examples #python code

Ray  Patel

Ray Patel

1626984360

Common Anti-Patterns in Python

Improve and streamline your code by learning about these common anti-patterns that will save you time and effort. Examples of good and bad practices included.

1. Not Using with to Open Files

When you open a file without the with statement, you need to remember closing the file via calling close() explicitly when finished with processing it. Even while explicitly closing the resource, there are chances of exceptions before the resource is actually released. This can cause inconsistencies, or lead the file to be corrupted. Opening a file via with implements the context manager protocol that releases the resource when execution is outside of the with block.

2. Using list/dict/set Comprehension Unnecessarily

3. Unnecessary Use of Generators

4. Returning More Than One Object Type in a Function Call

5. Not Using get() to Return Default Values From a Dictionary

#code reviews #python programming #debugger #code review tips #python coding #python code #code debugging