Can't use *ngIF inside *ngFor : angular2 [duplicate] - json

Question

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*ngIf and *ngFor on same element causing error
(17 answers)
Closed 5 years ago.
i'm using angular2 and i'im binding data from a service , the probleme is when i'm loading data i should filter it by an id , , this is what i'm supposed to do :
<md-radio-button
*ngFor="#item of items_list"
*ngIf="item.id=1"
value="{{item.value}}" class="{{item.class}}" checked="{{item.checked}}"> {{item.label}}
</md-radio-button>
and this is the data:
[
{ "id": 1, "value": "Fenêtre" ,"class":"md-primary" ,"label":"Fenêtre" ,"checked":"true"},
{ "id": 2, "value": "Porte Fenêtre" ,"class":"" ,"label":"Porte Fenêtre" }
]
by the way i want just the data with id =1 to be accepted , but i'm seeing this error:
EXCEPTION: Template parse errors:
Parser Error: Bindings cannot contain assignments at column 14 in [ngIf item.id=1] in RadioFormesType1Component#10:16 ("
<md-radio-button
*ngFor="#item of items_list"
[ERROR ->]*ngIf="item.id=1"
value="{{item.value}}" class="{{item.class}}" checked="{{item.check"): RadioFormesType1Component#10:16
so any suggestion to use ngif and ngfor together ?

Answer 1

You could use the following:
*ngIf="item.id===1"
instead of
*ngIf="item.id=1"
You try to assign something into the id property (operator =) instead of testing its value (operator == or ===).
Moreoever both ngFor and ngIf on the same element aren't supported. You could try something like that:
<div *ngFor="#item of items_list">
<md-radio-button
*ngIf="item.id===1"
value="{{item.value}}" class="{{item.class}}"
checked="{{item.checked}}">
{{item.label}}
</md-radio-button>
</div>
or
<template ngFor #item [ngForOf]="items_list">
<md-radio-button
*ngIf="item.id===1"
value="{{item.value}}" class="{{item.class}}"
checked="{{item.checked}}">
{{item.label}}
</md-radio-button>
</template>

Answer 2

Another solution is to create custom filtering pipe:
import {Pipe} from 'angular2/core';
#Pipe({name: 'filter'})
export class FilterPipe {
transform(value, filters) {
var filter = function(obj, filters) {
return Object.keys(filters).every(prop => obj[prop] === filters[prop])
}
return value.filter(obj => filter(obj, filters[0]));
}
}
and use it like this in component:
<md-radio-button
*ngFor="#item of items_list | filter:{id: 1}"
value="{{item.value}}" class="{{item.class}}" checked="{{item.checked}}"> {{item.label}}
</md-radio-button>
Custom pipe needs to be registered on the component:
#Component({
// ...
pipes: [FilterPipe]
})
Demo: http://plnkr.co/edit/LK5DsaeYnqMdScQw2HGv?p=preview

Answer 3

*ngIf and *ngFor on the same tag are not supported. You need to use the long form with an explicit <template> tag for one of them.
update
Instead of <template> use <ng-container> which allows to use the same syntax as inline *ngIf and *ngFor
<ng-container *ngFor="#item of items_list">
<md-radio-button
*ngIf="item.id=1"
value="{{item.value}}" class="{{item.class}}" checked="{{item.checked}}"> {{item.label}}
</md-radio-button>
</ng-container>