TextFormField Flutter更改不正确

问题描述

我有一个表单，希望从另一个窗口小部件按编程方式进行更新。为了测试这一点，我使用相同的文本对标签文本进行了更新，并按预期工作。

I have a form that I would like to be updated programatically from another widget is pressed. To test this I made the label text update with the same text and this worked as expected.

出于某种原因，即使在调试时，初始值也不会更新，但确实显示字符串是正确的值。我添加了一个控制器来处理文本，但我仍然不明白为什么初始值不能按我预期的方式工作。

For some reason the inital value is not updated even though in debugging it does show the string to be the correct value. I added a controller to handle the text but i still don't understand why the initial value was not working the way I thought it would.

new TextFormField(
          key: _orderAddEditOrderFormKey,
          decoration: InputDecoration(
              labelText: order.order == null ? 'Order' : order.order),
          initialValue: order.order == null ? "" : order.order,
        ),

setState(() {
            isBuildOrderUsed = true;
            if (this.order == null) {
              this.order = new Order(order: order);
            } else {
              this.order.order = order;
            }
          });

推荐答案

这是因为 initialValue 是通过 TextEditingController 在 initState 中设置的，因此您无法更新该值，它只是初始值。

That is because the initialValue is set in the initState with theTextEditingController so you can not update that value, it is just the 'initial value'.

检查 TextFormField 的源代码：

     @override
      void initState() {
        super.initState();
        if (widget.controller == null) {
          _controller = new TextEditingController(text: widget.initialValue);
        } else {
          widget.controller.addListener(_handleControllerChanged);
        }
      }

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