flutter setState: how to update with array?

Question

I have an array of small objects which is used to display List. What I'm doing now:

final _wordsList = <Word>[];
String triggerRerender;

getSharedText() async {
    var sharedData = await platform.invokeMethod("getSharedText");
    if (sharedData != null) {
      _wordsList.add(Word(sharedData));

      setState(() {
        triggerRerender = sharedData;
      });
    }
  }

and that feels wild. Shouldn't I be triggering rerender by changing array, not by some "trigger" primitive?

dumazy · Accepted Answer · 2019-08-18 07:07:59Z

4

You don't need to have a triggerRenderer, I think.

Here's what the docs say:

Whenever you change the internal state of a State object, make the change in a function that you pass to setState

Just update the data inside of the setState function:

final _wordsList = <Word>[];

getSharedText() async {
  var sharedData = await platform.invokeMethod("getSharedText");
  if (sharedData != null) {
    setState(() {
      _wordsList.add(Word(sharedData))
    });
  }
}

edited Aug 18, 2019 at 7:07

answered Aug 18, 2019 at 7:02

dumazy

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2 Comments

Undefitied Over a year ago

That has appeared so, thank you. Funny thing, that it also works, if I do: _wordsList.add(Word(sharedData)); setState(() { });. Hence seems like setState() doesn't look on what happens inside it's callback

dumazy Over a year ago

setState triggers the build() function. You can always set state and trigger the function later, but it's not recommended, because of the asynchronous way in which these things are executed, I think

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