我想验证 flutter 中的“文本”不是（TextFormField 或 Textfield）

Question

I want to validate "Text" in flutter not (TextFormField or Textfield), I want to check if the text is empty and if the text is empty then I want it to navigate to new page automatically.

So basically there's a Text widget where I am displaying data from Api using get method so what I want is, if the text widgets are empty, I want it to navigate to login page.

Answer 1

You need to store the string content of the concerned Text widget in a variable. Then you need to call a conditional operation on it to move to the new page.

Example:

String check = ""; (check == "")? Navigator.pushNamed((context), "/desired-routeName"): Text(check),

Answer 2

simply you can check by == "";for example:

String myText = ""

bool isEmpty(String text) => text == "";


isEmpty(myText); //returns true
//now set some value
myText = "some value"
isEmpty(myText); //returns false

then you can navigate based on condition like:

if (isEmpty(myText))
{ //navigation logic goes here
} else {
}

Answer 3

Method 1. You can declare a variable and pass it to the Text widget. Put your condition on that variable.

Method 2. Save your Text Widget into a variable and use the data: String? property to access the text inside Text widget.

final textWidget = const Text("Hello World");

if(textWidget.data?.isEmpty()) {
      //...
}
else {
      //...   
}

You can put the condition in didChangeDipendencies() or initState() if you wanna to navigate to new page without any click event.

Answer 4

If you get data from api, i would recommend you to validate your string data with regular expressions. To check empty strings you can se the follow regex.

RegExp regExp = new RegExp(r"^$",caseSensitive: false, multiLine: false,);

if(regExp.allMatches(yourValue)){
  Navigator.push(context,MaterialPageRoute(builder: (context) => const SecondRoute()),);
}