how to use condition in this button to show alertdialog in flutter? - flutter

Question

productDetails
child: ButtonTheme(
child: (TextButton(
child: Text(
'Demande de prix',
style: TextStyle(
color: Colors.white,
fontSize: 12,
fontWeight: FontWeight.w600),
),
style: TextButton.styleFrom(
primary: Colors.white,
backgroundColor: Color(0xFF2664B5),
onSurface: Colors.white,
),
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) => DemandeDevis(
productName:
(selectedProduitslist[index]
.titre)
.toUpperCase(),
),
),
);
},
)),
),
2.demandedevis
AlertDialog(
backgroundColor: Colors.white,
elevation: 20,
content: SingleChildScrollView(
child: Form(
key: _formKey,
child: ListBody(
children: <Widget>[
Container(
child: Text(
"Demande de prix",
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.blue[900],
fontSize: 20,
fontWeight: FontWeight.bold),
),
),
Container(
width: ResponsiveFlutter.of(context).wp(50),
padding: EdgeInsets.all(3),
child: TextFormField(
controller: largeurController,
style: TextStyle(color: Colors.black),
keyboardType: TextInputType.phone,
// validator: (text) {
// if (text == null || text.isEmpty) {
// return "Champ obligatoire";
// }
// return null;
// },
decoration: InputDecoration(
fillColor: Colors.white,
filled: true,
hintText: 'Largeur (m)',
hintStyle: TextStyle(
color: Colors.blue[900],
fontSize: 10,
),
focusedBorder: OutlineInputBorder(
borderSide:
BorderSide(color: Colors.blue[900], width: 0.5),
borderRadius: BorderRadius.circular(3.0),
),
contentPadding:
const EdgeInsets.symmetric(horizontal: 20, vertical: 0),
border: OutlineInputBorder(
borderRadius: BorderRadius.circular(3.0),
),
),
),
),
Container(
width: ResponsiveFlutter.of(context).wp(50),
padding: EdgeInsets.all(3),
child: TextFormField(
controller: longeurController,
style: TextStyle(color: Colors.black),
keyboardType: TextInputType.phone,
// validator: (text) {
// if (text == null || text.isEmpty) {
// return "Champ obligatoire";
// }
// return null;
// },
decoration: InputDecoration(
fillColor: Colors.white,
filled: true,
hintText: 'Longeur (m)',
hintStyle: TextStyle(
color: Colors.blue[900],
fontSize: 10,
),

Answer 1

I'm assuming that you are asking how to show a dialog when a button is pressed.
Every button has an onPressed : argument, in that onPressed function you can execute the showDialog() function to show a dialog in the UI. Given below is the code snippet.
TextButton(
child: Text(
'Yes!',
style: TextStyle(color: Theme.of(context).accentColor),),
onPressed: () =>
{
//This is the function that will execute when the button is pressed
showDialog(
context : context,
builder : (context) => AlertDialog()
);
},
),
);

Answer 2

I believe you would like to do some onPressed functionality based on condition, like if(condition) do that, else do that...
You could do this by inline condition, also called ternary operator.
For example:
onPressed: (condition != null) ? () => Navigator.push() : () => showAlertDialog()
You read this like:
(your condition) ? [if true ->] do that : [else ->] do that.
You could also nest this expression.
As an alternative you could add a function, which calls other conditioned functions.
...
onPressed: _decisionFunction,
...
void _decisionFunction(){
if(condition == true){
Navigator.push(...);
} else {
showDialog(...);
}
}