flutter form bloc
create beautiful forms in flutter. the easiest way to prefill, async validation, update form fields, and show progress, failures, successes or navigate by reacting to the form state.
separate the form state and business logic from the user interface using form_bloc.
before to use this package you need to know the core concepts of bloc package and the basics of flutter_bloc
widgets
- textfieldblocbuilder: a material design text field that can show suggestions.
- dropdownfieldblocbuilder: a material design dropdown.
- radiobuttongroupfieldblocbuilder: a material design radio buttons.
- checkboxfieldblocbuilder: a material design checkbox.
- checkboxgroupfieldblocbuilder: a material design checkboxes.
- formbloclistener: bloclistener that reacts to the state changes of the formbloc.
note
formbloc, inputfieldbloc, textfieldbloc, booleanfieldbloc, selectfieldbloc, multiselectfieldbloc are blocs, so you can use blocbuilder or bloclistener of flutter_bloc for make any widget you want compatible with any fieldbloc
or formbloc
.
if you want me to add other widgets please let me know, or make a pull request.
examples
- fieldblocs with async validation: bloc – ui.
- manually set fieldbloc error: bloc – ui.
- formbloc with submission progress: bloc – ui.
- formbloc without auto validation: bloc – ui.
- complex async prefilled formbloc: bloc – ui.
- and more examples.
basic example
dependencies:
form_bloc: ^0.5.1
flutter_form_bloc: ^0.4.2
flutter_bloc: ^0.21.0
import 'package:form_bloc/form_bloc.dart';
class loginformbloc extends formbloc<string, string> {
final emailfield = textfieldbloc(validators: [validators.email]);
final passwordfield = textfieldbloc();
final userrepository _userrepository;
loginformbloc(this._userrepository);
@override
list<fieldbloc> get fieldblocs => [emailfield, passwordfield];
@override
stream<formblocstate<string, string>> onsubmitting() async* {
try {
_userrepository.login(
email: emailfield.value,
password: passwordfield.value,
);
yield currentstate.tosuccess();
} catch (e) {
yield currentstate.tofailure();
}
}
}
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_form_bloc/flutter_form_bloc.dart';
import 'package:flutter_form_bloc_example/forms/simple_login_form_bloc.dart';
import 'package:flutter_form_bloc_example/widgets/widgets.dart';
class loginform extends statelesswidget {
@override
widget build(buildcontext context) {
return blocprovider<loginformbloc>(
builder: (context) =>
loginformbloc(repositoryprovider.of<userrepository>(context)),
child: builder(
builder: (context) {
final formbloc = blocprovider.of<loginformbloc>(context);
return scaffold(
appbar: appbar(title: text('simple login')),
body: formbloclistener<loginformbloc, string, string>(
onsubmitting: (context, state) => loadingdialog.show(context),
onsuccess: (context, state) {
loadingdialog.hide(context);
navigator.of(context).pushreplacementnamed('success');
},
onfailure: (context, state) {
loadingdialog.hide(context);
notifications.showsnackbarwitherror(
context, state.failureresponse);
},
child: listview(
children: <widget>[
textfieldblocbuilder(
textfieldbloc: formbloc.emailfield,
keyboardtype: textinputtype.emailaddress,
decoration: inputdecoration(
labeltext: 'email',
prefixicon: icon(icons.email),
),
),
textfieldblocbuilder(
textfieldbloc: formbloc.passwordfield,
suffixbutton: suffixbutton.obscuretext,
decoration: inputdecoration(
labeltext: 'password',
prefixicon: icon(icons.lock),
),
),
padding(
padding: const edgeinsets.all(8.0),
child: raisedbutton(
onpressed: formbloc.submit,
child: center(child: text('login')),
),
),
],
),
),
);
},
),
);
}
}
basic usage
1. import it
import 'package:form_bloc/form_bloc.dart';
2. create a class that extends formbloc<successresponse, failureresponse>
formbloc<successresponse, failureresponse>
successresponse
the type of the success response.
failureresponse
the type of the failure response.
for example, the successresponse
type and failureresponse
type of loginformbloc
will be string
.
import 'package:form_bloc/form_bloc.dart';
class loginformbloc extends formbloc<string, string> {}
2. create field blocs
you need to create field blocs, and these need to be final.
you can create:
- inputfieldbloc
<value>
. - textfieldbloc.
- booleanfieldbloc.
- selectfieldbloc
<value>
. - multiselectfieldbloc
<value>
.
for example the loginformbloc
will have two textfieldbloc
.
import 'package:form_bloc/form_bloc.dart';
class loginformbloc extends formbloc<string, string> {
final emailfield = textfieldbloc(validators: [validators.email]);
final passwordfield = textfieldbloc();
}
3. add services/repositories
in this example we need a userrepository
for make the login.
import 'package:form_bloc/form_bloc.dart';
class loginformbloc extends formbloc<string, string> {
final emailfield = textfieldbloc(validators: [validators.email]);
final passwordfield = textfieldbloc();
final userrepository _userrepository;
loginformbloc(this._userrepository);
}
4. implement the get method fieldblocs
you need to override the get method fieldblocs and return a list with all fieldblocs
.
for example the loginformbloc
need to return a list with emailfield
and passwordfield
.
import 'package:form_bloc/form_bloc.dart';
class loginformbloc extends formbloc<string, string> {
final emailfield = textfieldbloc(validators: [validators.email]);
final passwordfield = textfieldbloc();
final userrepository _userrepository;
loginformbloc(this._userrepository);
@override
list<fieldbloc> get fieldblocs => [emailfield, passwordfield];
}
5. implement onsubmitting method
onsubmitting returns a stream<formblocstate<successresponse, failureresponse>>
.
this method is called when you call loginformbloc.submit()
and formblocstate.isvalid
is true
, so each field bloc has a valid value.
you can get the current value
of each field bloc calling emailfield.value
or passwordfield.value
.
you must call all your business logic of this form here, and yield
the corresponding state.
you can yield a new state using:
- currentstate.tofailure([failureresponse failureresponse]).
- currentstate.tosuccess([successresponse successresponse]).
- currentstate.toloaded().
see other states here.
for example onsubmitting
of loginformbloc
will return a stream<formblocstate<string, string>>
and yield currentstate.tosuccess()
if the _userrepository.login
method not throw any exception, and yield “currentstate.tofailure()` if throw a exception.
import 'package:form_bloc/form_bloc.dart';
class loginformbloc extends formbloc<string, string> {
final emailfield = textfieldbloc(validators: [validators.email]);
final passwordfield = textfieldbloc();
final userrepository _userrepository;
loginformbloc(this._userrepository);
@override
list<fieldbloc> get fieldblocs => [emailfield, passwordfield];
@override
stream<formblocstate<string, string>> onsubmitting() async* {
try {
_userrepository.login(
email: emailfield.value,
password: passwordfield.value,
);
yield currentstate.tosuccess();
} catch (e) {
yield currentstate.tofailure();
}
}
}
6. create a form widget
you need to create a widget with access to the formbloc
.
in this case i will use blocprovider
for do it.
class loginform extends statelesswidget {
@override
widget build(buildcontext context) {
return blocprovider<loginformbloc>(
builder: (context) =>
loginformbloc(repositoryprovider.of<userrepository>(context)),
child: builder(
builder: (context) {
final formbloc = blocprovider.of<loginformbloc>(context);
return scaffold();
},
),
);
}
}
6. add formbloclistener for manage form state changes
you need to add a formbloclistener
.
in this example:
- i will show a loading dialog when the state is loading.
- i will hide the dialog when the state is success, and navigate to success screen.
- i will hide the dialog when the state is failure, and show a snackbar with the error.
...
return scaffold(
appbar: appbar(title: text('simple login')),
body: formbloclistener<loginformbloc, string, string>(
onsubmitting: (context, state) => loadingdialog.show(context),
onsuccess: (context, state) {
loadingdialog.hide(context);
navigator.of(context).pushreplacementnamed('success');
},
onfailure: (context, state) {
loadingdialog.hide(context);
notifications.showsnackbarwitherror(
context, state.failureresponse);
},
child:
),
),
);
...
6. connect the field blocs with field blocs builder
in this example i will use textfieldblocbuilder
for connect with emailfield
and passwordfield
of loginformbloc
.
...
child: listview(
children: <widget>[
textfieldblocbuilder(
textfieldbloc: formbloc.emailfield,
keyboardtype: textinputtype.emailaddress,
decoration: inputdecoration(
labeltext: 'email',
prefixicon: icon(icons.email),
),
),
textfieldblocbuilder(
textfieldbloc: formbloc.passwordfield,
suffixbutton: suffixbutton.obscuretext,
decoration: inputdecoration(
labeltext: 'password',
prefixicon: icon(icons.lock),
),
),
],
),
...
7. add a widget for submit the formbloc
in this example i will add a raisedbutton
and pass submit
method of formbloc
to submit the form.
...
child: listview(
children: <widget>[
...,
padding(
padding: const edgeinsets.all(8.0),
child: raisedbutton(
onpressed: formbloc.submit,
child: center(child: text('login')),
),
),
],
),
...
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