TextField content checking-CodePudding

I have a textfield and i want to ensure the data or entry is not more than the intended value.example "the value to be entered should not be more than $4000".

i did some research but i still have been able to solve the problem.

TextFormField(
                                  
                                  decoration: InputDecoration(
                                    hintStyle: TextStyle(
                                      fontFamily: "Proxima Nova",
                                      fontWeight: FontWeight.w300,
                                    ),
                                    border: InputBorder.none,
                                    labelStyle: TextStyle(
                                      color: Color(0xffFAFAFA),
                                    ),
                                  ),
                                  inputFormatters: [
                                    FilteringTextInputFormatter.allow(
                                        RegExp(r"[0-9] |\s"))
                                  ],
                                  controller: kiloMeter,
                                  validator: (value) {
                                    if (value != null &&
                                        value.isEmpty &&
                                        value.length < 4) {
                                      return 'Please enter the price you want to purchase';
                                    }
                                    return null;
                                  },
                                )
                              : const SizedBox(
                                  height: 120,
                                );

CodePudding user response：

Try the following code:

TextFormField(
                                  keyboardType: TextInputType.number,
                                  decoration: InputDecoration(
                                    hintStyle: TextStyle(
                                      fontFamily: "Proxima Nova",
                                      fontWeight: FontWeight.w300,
                                    ),
                                    border: InputBorder.none,
                                    labelStyle: TextStyle(
                                      color: Color(0xffFAFAFA),
                                    ),
                                  ),
                                  controller: kiloMeter,
                                  validator: (value) {
                                    if (value != null && value.isEmpty && int.parse(value) > 4000) {
                                      return 'Please enter the price you want to purchase';
                                    }
                                    return null;
                                  },
                                )
                              : const SizedBox(
                                  height: 120,
                                );

CodePudding user response：

You have to use parsing in the validator to check the value

You can easily convert the string value that comes from the TextFormField to int by use int.parse(value).

So your code would be:

TextFormField(
                                  
                                  decoration: InputDecoration(
                                    hintStyle: TextStyle(
                                      fontFamily: "Proxima Nova",
                                      fontWeight: FontWeight.w300,
                                    ),
                                    border: InputBorder.none,
                                    labelStyle: TextStyle(
                                      color: Color(0xffFAFAFA),
                                    ),
                                  ),
                                  inputFormatters: [
                                    FilteringTextInputFormatter.allow(
                                        RegExp(r"[0-9] |\s"))
                                  ],
                                  controller: kiloMeter,
                                  validator: (value) {
                                    if (value != null &&
                                        value.isEmpty &&
                                        int.parse(value) <= 4000 {
                                      return 'Please enter the price you want to purchase';
                                    }
                                    return null;
                                  },
                                )
                              : const SizedBox(
                                  height: 120,
                                );