A TypeAhead (autocomplete) widget for Flutter, where you can show suggestions to users as they type
See the installation instructions on pub.
You can import the package with:
import 'package:flutter_typeahead/flutter_typeahead.dart';
For Cupertino users import:
import 'package:flutter_typeahead/cupertino_flutter_typeahead.dart';
Use it as follows:
TypeAheadField(
textFieldConfiguration: TextFieldConfiguration(
autofocus: true,
style: DefaultTextStyle.of(context).style.copyWith(
fontStyle: FontStyle.italic
),
decoration: InputDecoration(
border: OutlineInputBorder()
)
),
suggestionsCallback: (pattern) async {
return await BackendService.getSuggestions(pattern);
},
itemBuilder: (context, suggestion) {
return ListTile(
leading: Icon(Icons.shopping_cart),
title: Text(suggestion['name']),
subtitle: Text('\$${suggestion['price']}'),
);
},
onSuggestionSelected: (suggestion) {
Navigator.of(context).push(MaterialPageRoute(
builder: (context) => ProductPage(product: suggestion)
));
},
)
In the code above, the textFieldConfiguration
property allows us to configure the displayed TextField
as we want. In this example, we are configuring the autofocus
, style
and decoration
properties.
The suggestionsCallback
is called with the search string that the user types, and is expected to return a List
of data either synchronously or asynchronously. In this example, we are calling an asynchronous function called BackendService.getSuggestions
which fetches the list of suggestions.
The itemBuilder
is called to build a widget for each suggestion. In this example, we build a simple ListTile
that shows the name and the price of the item. Please note that you shouldn’t provide an onTap
callback here. The TypeAhead widget takes care of that.
The onSuggestionSelected
is a callback called when the user taps a suggestion. In this example, when the user taps a suggestion, we navigate to a page that shows us the information of the tapped product.
Here’s another example, where we use the TypeAheadFormField inside a Form
:
final GlobalKey<FormState> _formKey = GlobalKey<FormState>();
final TextEditingController _typeAheadController = TextEditingController();
String _selectedCity;
...
Form(
key: this._formKey,
child: Padding(
padding: EdgeInsets.all(32.0),
child: Column(
children: <Widget>[
Text(
'What is your favorite city?'
),
TypeAheadFormField(
textFieldConfiguration: TextFieldConfiguration(
controller: this._typeAheadController,
decoration: InputDecoration(
labelText: 'City'
)
),
suggestionsCallback: (pattern) {
return CitiesService.getSuggestions(pattern);
},
itemBuilder: (context, suggestion) {
return ListTile(
title: Text(suggestion),
);
},
transitionBuilder: (context, suggestionsBox, controller) {
return suggestionsBox;
},
onSuggestionSelected: (suggestion) {
this._typeAheadController.text = suggestion;
},
validator: (value) {
if (value.isEmpty) {
return 'Please select a city';
}
},
onSaved: (value) => this._selectedCity = value,
),
SizedBox(height: 10.0,),
RaisedButton(
child: Text('Submit'),
onPressed: () {
if (this._formKey.currentState.validate()) {
this._formKey.currentState.save();
Scaffold.of(context).showSnackBar(SnackBar(
content: Text('Your Favorite City is ${this._selectedCity}')
));
}
},
)
],
),
),
)
Here, we assign to the controller
property of the textFieldConfiguration
a TextEditingController
that we call _typeAheadController
. We use this controller in the onSuggestionSelected
callback to set the value of the TextField
to the selected suggestion.
The validator
callback can be used like any FormField.validator
function. In our example, it checks whether a value has been entered, and displays an error message if not. The onSaved
callback is used to save the value of the field to the _selectedCity
member variable.
The transitionBuilder
allows us to customize the animation of the suggestion box. In this example, we are returning the suggestionsBox immediately, meaning that we don’t want any animation.
Please see the Cupertino code in the example project.
Placing TypeAheadField in widgets with animations may cause the suggestions box to resize incorrectly. Since animation times are variable, this has to be corrected manually at the end of the animation. You will need to add a SuggestionsBoxController described below and the following code for the AnimationController.
void Function(AnimationStatus) _statusListener;
@override
void initState() {
super.initState();
_statusListener = (AnimationStatus status) {
if (status == AnimationStatus.completed ||
status == AnimationStatus.dismissed) {
_suggestionsBoxController.resize();
}
};
_animationController.addStatusListener(_statusListener);
}
@override
void dispose() {
_animationController.removeStatusListener(_statusListener);
_animationController.dispose();
super.dispose();
}
There is a known issue with opening dialogs where the suggestions box will sometimes appear too small. This is a timing issue caused by the animations described above. Currently, showDialog
has a duration of 150 ms for the animations. TypeAheadField has a delay of 170 ms to compensate for this. Until the end of the animation can be properly detected and fixed using the solution above, this temporary fix will work most of the time. If the suggestions box is too small, closing and reopening the keyboard will usually fix the issue.
The Cupertino classes in TypeAhead are still new. There are also differences in the Cupertino widgets vs the Material ones. Some behavior will not translate when moving between the two.
TypeAhead widgets consist of a TextField and a suggestion box that shows as the user types. Both are highly customizable
You can customize the text field using the textFieldConfiguration
property. You provide this property with an instance of TextFieldConfiguration
, which allows you to configure all the usual properties of TextField
, like decoration
, style
, controller
, focusNode
, autofocus
, enabled
, etc.
TypeAhead provides default configurations for the suggestions box. You can, however, override most of them. This is done by passing a SuggestionsBoxDecoration
to the suggestionsBoxDecoration
property.
Use the offsetX
property in SuggestionsBoxDecoration
to shift the suggestions box along the x-axis. You may also pass BoxConstraints to constraints
in SuggestionsBoxDecoration
to adjust the width and height of the suggestions box. Using the two together will allow the suggestions box to be placed almost anywhere.
You can use the loadingBuilder
, errorBuilder
and noItemsFoundBuilder
to customize their corresponding widgets. For example, to show a custom error widget:
errorBuilder: (BuildContext context, Object error) =>
Text(
'$error',
style: TextStyle(
color: Theme.of(context).errorColor
)
)
By default, the suggestions box will maintain the old suggestions while new suggestions are being retrieved. To show a circular progress indicator during retrieval instead, set keepSuggestionsOnLoading
to false.
There are three scenarios when you can hide the suggestions box.
Set hideOnLoading
to true to hide the box while suggestions are being retrieved. This will also ignore the loadingBuilder
. Set hideOnEmpty
to true to hide the box when there are no suggestions. This will also ignore the noItemsFoundBuilder
. Set hideOnError
to true to hide the box when there is an error retrieving suggestions. This will also ignore the errorBuilder
.
By default, the suggestions box will automatically hide when the keyboard is hidden. To change this behavior, set hideSuggestionsOnKeyboardHide
to false.
You can customize the suggestion box animation through 3 parameters: the animationDuration
, the animationStart
, and the transitionBuilder
.
The animationDuration
specifies how long the animation should take, while the animationStart
specified what point (between 0.0 and 1.0) the animation should start from. The transitionBuilder
accepts the suggestionsBox
and animationController
as parameters, and should return a widget that uses the animationController
to animate the display of the suggestionsBox
. For example:
transitionBuilder: (context, suggestionsBox, animationController) =>
FadeTransition(
child: suggestionsBox,
opacity: CurvedAnimation(
parent: animationController,
curve: Curves.fastOutSlowIn
),
)
This uses FadeTransition to fade the suggestionsBox
into the view. Note how the animationController
was provided as the parent of the animation.
In order to fully remove the animation, transitionBuilder
should simply return the suggestionsBox
. This callback could also be used to wrap the suggestionsBox
with any desired widgets, not necessarily for animation.
The suggestions box does not fire for each character the user types. Instead, we wait until the user is idle for a duration of time, and then call the suggestionsCallback
. The duration defaults to 300 milliseconds, but can be configured using the debounceDuration
parameter.
By default, the suggestions box is displayed 5 pixels below the TextField
. You can change this by changing the suggestionsBoxVerticalOffset
property.
You can also customize the decoration of the suggestions box using the suggestionsBoxDecoration
property. For example, to remove the elevation of the suggestions box, you can write:
suggestionsBoxDecoration: SuggestionsBoxDecoration(
elevation: 0.0
)
By default, the list grows towards the bottom. However, you can use the direction
property to customize the growth direction to be one of AxisDirection.down
or AxisDirection.up
, the latter of which will cause the list to grow up, where the first suggestion is at the bottom of the list, and the last suggestion is at the top.
Set autoFlipDirection
to true to allow the suggestions list to automatically flip direction whenever it detects that there is not enough space for the current direction. This is useful for scenarios where the TypeAheadField is in a scrollable widget or when the developer wants to ensure the list is always viewable despite different user screen sizes.
Manual control of the suggestions box can be achieved by creating an instance of SuggestionsBoxController
and passing it to the suggestionsBoxController
property. This will allow you to manually open, close, toggle, or resize the suggestions box.
Visit the API Documentation
Author: AbdulRahmanAlHamali
Source Code: https://github.com/AbdulRahmanAlHamali/flutter_typeahead
#flutter #dart #mobile-apps