flutter - Flutter 2 - 设置自动完成 TextFormField 的初始值

Question

我不能使用TextEditingController，因为TextFormField使用Autocomplete fieldViewBuilder TextEditingController

Autocomplete(
                optionsBuilder: (TextEditingValue textEditingValue) {
                  if (textEditingValue.text == '') return [];

                  return this
                      .productNames
                      .where((Map<String, dynamic> option) {
                    return option['ar']
                        .toLowerCase()
                        .contains(textEditingValue.text.toLowerCase());
                  });
                },
                fieldViewBuilder: (context, textEditingController,
                        focusNode, onFieldSubmitted) =>
                    TextFormField(                             
                  controller: textEditingController,//uses fieldViewBuilder TextEditingController
                   focusNode: focusNode,
                ),
              ),

Answer 1

编辑

我刚刚意识到您正在使用 TextFormField，它有一个名为 initialValue 的参数。如果您不需要文本编辑控制器，则此答案应该有效

fieldViewBuilder: (context, textEditingController,
                        focusNode, onFieldSubmitted) =>
                    TextFormField(                             
             
                   focusNode: focusNode,
                   initialValue:"Your initial Value",
                ),

或者如果您使用的是控制器，请尝试

fieldViewBuilder: (context, textEditingController,
                        focusNode, onFieldSubmitted) =>
                    TextFormField(                             
                  controller: textEditingController..text="Initial Value",
                   focusNode: focusNode,
                ),

原始答案

为什么不使用该文本编辑控制器本身。代码将是这样的

Autocomplete(
                optionsBuilder: (TextEditingValue textEditingValue) {
                  if (textEditingValue.text == '') return [];

                  return this
                      .productNames
                      .where((Map<String, dynamic> option) {
                    return option['ar']
                        .toLowerCase()
                        .contains(textEditingValue.text.toLowerCase());
                  });
                },
                fieldViewBuilder: (context, textEditingController,
                        focusNode, onFieldSubmitted){
                    textEditingController.text  = "Your initial text";// You can use the next snip of code if you dont want the initial text to come when you use setState((){});  
                    return TextFormField(                             
                  controller: textEditingController,//uses fieldViewBuilder TextEditingController
                   focusNode: focusNode,
                ),
               }
              ),

如果您正在使用 setState 并且上面的代码一直用初始文本替换文本，请执行以下操作

Autocomplete(
                optionsBuilder: (TextEditingValue textEditingValue) {
                  if (textEditingValue.text == '') return [];

                  return this
                      .productNames
                      .where((Map<String, dynamic> option) {
                    return option['ar']
                        .toLowerCase()
                        .contains(textEditingValue.text.toLowerCase());
                  });
                },
                fieldViewBuilder: (context, textEditingController,
                        focusNode, onFieldSubmitted){
                    textEditingController.text = textEditingController.text  == ""? "Inital Text":textEditingController.text;// You can use the next snip of code if you dont want the initial text to come when you use setState((){});  
                    return TextFormField(                             
                  controller: textEditingController,//uses fieldViewBuilder TextEditingController
                   focusNode: focusNode,
                ),
               }
              ),

最后一个解决方案不太优雅但有效。如果我找到更好的解决方案，我会告诉你。您甚至可以将此 textEditingController 分配给在顶部声明的全局变量，并从代码中的任何位置访问它。而不是检查文本是否为空，而是在每次 setState 时增加一个新变量的值，如果值为 == 0，则可以设置初始文本

Answer 2

自动完成对此有一个命名参数initialValue。

Autocomplete<AutocompletePrediction>(  
    initialValue: const TextEditingValue(text: "Initial value"),  
    fieldViewBuilder: ...
    ...  
)  

Answer 3

这是我找到的解决方案TextFormField。确保控制器在帧结束时更新。

fieldViewBuilder: (BuildContext context,
  TextEditingController fieldTextEditingController,
  FocusNode fieldFocusNode,
  VoidCallback onFieldSubmitted) {

  SchedulerBinding.instance?.addPostFrameCallback((_) { // <--- this part
    var initialValue = someValueThatGotUpdatedDuringBuild;

    fieldTextEditingController.text = initialValue;
  });
  return TextFormField(...);
}
...