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addfff3c46
Instead of throwing an error when using "track by" and "select as" expressions, ngOptions will assume that the track by expression is valid, and will use it to compare values. Closes #6564
34 lines
1.6 KiB
Plaintext
34 lines
1.6 KiB
Plaintext
@ngdoc error
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@name ngOptions:trkslct
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@fullName Comprehension expression cannot contain both `select as` and `track by` expressions.
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@description
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NOTE: This error was introduced in 1.3.0-rc.5, and was removed for 1.3.0-rc.6 in order to
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not break existing apps.
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This error occurs when 'ngOptions' is passed a comprehension expression that contains both a
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`select as` expression and a `track by` expression. These two expressions are fundamentally
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incompatible.
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* Example of bad expression: `<select ng-options="item.subItem as item.label for item in values track by item.id" ng-model="selected">`
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`values: [{id: 1, label: 'aLabel', subItem: {name: 'aSubItem'}}, {id: 2, label: 'bLabel', subItem: {name: 'bSubItem'}}]`,
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`$scope.selected = {name: 'aSubItem'};`
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* track by is always applied to `value`, with purpose to preserve the selection,
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(to `item` in this case)
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* To calculate whether an item is selected, `ngOptions` does the following:
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1. apply `track by` to the values in the array:
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In the example: [1,2]
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2. apply `track by` to the already selected value in `ngModel`:
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In the example: this is not possible, as `track by` refers to `item.id`, but the selected
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value from `ngModel` is `{name: aSubItem}`.
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Here's an example of how to make this example work by using `track by` without `select as`:
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```
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<select ng-model="selected" ng-options="item.label for item in values track by item.id">
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```
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Note: This would store the whole `item` as the model to `scope.selected` instead of `item.subItem`.
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For more information on valid expression syntax, see 'ngOptions' in {@link ng.directive:select select} directive docs.
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