ngrx: check is store already have the same object before dispatch action

Question

I have action, which add new object to a store:

let warning = {message: 'some text', status: 'suspended'} 
this.store.dispatch(new WarningActions.AddWarning(warning))

but if I already have the same warning, I don't want to add it again, so I tried to check store before dispatch it:

this.store.select('warning').subscribe(warnings => {
   console.log(warnings) // [{message: 'some text', status: 'suspended'}]
   if (warnings.indexOf(warning) === -1) {
     this.store.dispatch(new WarningActions.AddWarning(warning))
   }
})

But this is does not work, because warnings.indexOf(warning) === -1 always yields true, even if I already have exactly the same object. What I did wrong and how I can solve this?

what if you do the same on reducer? and if it's exists don't update store — Reza, Aug 12 '19 at 19:33

score 1 · Accepted Answer · answered Aug 12 '19 at 19:35

1

indexOf() will always return -1 because they are two distinct objects and cannot equal even if they look the same (i.e. have the same properties and values).

you may use the some method to find if the properties are same.

answered Aug 12 '19 at 19:35

iams0nus

481
3
8

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if(warnings.some(warn => warn.message ===warning.message && warn.status === warning.status)){} – iams0nus Aug 12 '19 at 19:38
You could include the code sample in the answer (instead of giving it as a comment). – ConnorsFan Aug 12 '19 at 21:15

score 1 · Answer 2 · answered Aug 12 '19 at 19:36

1

You can not deeply compare objects in Javascript this way. {} === {} is false no matter what you do. You need to compare the properties manually. If you want deep comparison in JS have a look at this post.

answered Aug 12 '19 at 19:36

Felix Lemke

6,189
3
40
67

ngrx: check is store already have the same object before dispatch action

2 Answers2