Text Field obscure text cannot be used with expands to true #89502
Description
Putting an assert to check whether the text is a single line if it is obscured is a good idea when we think first. However, when we do like that we also avoid the use of "expands" property. For example, if I create a login screen with a password text form field wrapped with an expanded widget, I cannot fill the full size inside of the expanded with a text form field. The reason why I can't do it is the fact that obscured texts cannot be multiline and max lines should be null (cannot be 1) when expands is true. These two asserts lead to the problem and this problem leads to significant design issues especially when we are dealing with websites developed with Flutter Web since their size can be any.
Like it is mentioned in:
"the problem is that if i try to use a text field (obscure) that occupies the entire space of a container using Expands: true and max Lines: null, it will not work, only the text without obscure now.. :/"
Originally posted by @FilipeAG in #41853 (comment)
Use this code piece in any project to reproduce the issue:
Expanded(
child: TextFormField(
controller: controller, // Declare above
obscureText: true,
),
);
When you use the above code, TextFormField doesn't fill the all space of its parent since the obscured text form fields are forced to be "one" line. If we want to use the "expands" parameter of TextFormField as true, it doesn't pass the following assert:
assert(
!expands || (maxLines == null && minLines == null),
'minLines and maxLines must be null when expands is true.',
),
If we try to set minLines and maxLines as null, then it doesn't pass the following assert:
assert(!obscureText || maxLines == 1, 'Obscured fields cannot be multiline.'),
So each assert leads to failure in another assert like the links of a chain.
In short: "How can we create an obscured TextFormField that expands the parent widget?"
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