useful error when switching numColumns on the fly

sahrens · facebook-github-bot · commit 46d6766a53f6 · 2017-03-21T22:30:30.000-07:00
Reviewed By: blairvanderhoof, bvaughn

Differential Revision: D4742842

fbshipit-source-id: a11a088194ead02cc11eb6ccd9ce6d6f75ead3a3
diff --git a/Libraries/CustomComponents/Lists/FlatList.js b/Libraries/CustomComponents/Lists/FlatList.js
@@ -242,6 +242,11 @@ class FlatList<ItemT> extends React.PureComponent<DefaultProps, Props<ItemT>, vo
   }
 
   componentWillReceiveProps(nextProps: Props<ItemT>) {
+    invariant(
+      nextProps.numColumns === this.props.numColumns,
+      'Changing numColumns on the fly is not supported. Change the key prop on FlatList when ' +
+      'changing the number of columns to force a fresh render of the component.'
+    );
     this._checkProps(nextProps);
   }
 

Original file line number	Diff line number	Diff line change
`@@ -242,6 +242,11 @@ class FlatList<ItemT> extends React.PureComponent<DefaultProps, Props<ItemT>, vo`
`242`	`242`	`}`
`243`	`243`
`244`	`244`	`componentWillReceiveProps(nextProps: Props<ItemT>) {`
	`245`	`+ invariant(`
	`246`	`+ nextProps.numColumns === this.props.numColumns,`
	`247`	`+ 'Changing numColumns on the fly is not supported. Change the key prop on FlatList when ' +`
	`248`	`+ 'changing the number of columns to force a fresh render of the component.'`
	`249`	`+ );`
`245`	`250`	`this._checkProps(nextProps);`
`246`	`251`	`}`
`247`	`252`