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FirebaseListObservables retrieve the initial list content twice #819

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cartant opened this issue Feb 10, 2017 · 1 comment · Fixed by #826
Closed

FirebaseListObservables retrieve the initial list content twice #819

cartant opened this issue Feb 10, 2017 · 1 comment · Fixed by #826

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@cartant
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cartant commented Feb 10, 2017

Version info

Angular: 2.4.7
Firebase: 3.6.9
AngularFire: 2.0.0-beta.7
Other (e.g. Ionic/Cordova, Node, browser, operating system): N/A

How to reproduce these conditions

Failing test unit, Plunkr, or JSFiddle demonstrating the problem

There is a plunk here.

Steps to set up and reproduce

Open the above plunk and then:

  • Open the Dev Tools and go to the Network tab.
  • Select WS or All to observe the WebSocket traffic.
  • Run the plunk.
  • There will be an entry of about 7557 bytes which is the initial content written to the database.
  • That entry will be followed by two of about 7550 bytes and those entries are the content thats read from the database.

The problem is caused by on('child_added', ...) not being called until after the on('value') promise has resolved.

Expected behavior

When subscribing to a FirebaseListObservable that has content that exists in the database, a single copy of the content should be retrieved across the network.

Actual behavior

Two copies of the content are retrieved across the network.
cartant added a commit to cartant/angularfire that referenced this issue Feb 10, 2017
@cartant
fix(database): retrieve initial list content once
03abbed 
Closes angular#819
@cartant cartant mentioned this issue Feb 10, 2017
Merged
davideast pushed a commit that referenced this issue Feb 15, 2017
@cartant @davideast
fix(database): retrieve initial list content once (#820)
5c5ff7b 
* fix(database): retrieve initial list content once

Closes #819

* test(database): add a child_added quirk test
@davideast davideast mentioned this issue Feb 16, 2017
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@alixaxel
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@davideast @cartant I noticed this is still happening with the latest release 5.0.0-rc.11.

Here's a StackBlitz demonstrating the same behavior: https://stackblitz.com/edit/angular-rxjs6-f2ey8o

image

Is this a regression?

@alixaxel alixaxel mentioned this issue Aug 17, 2018
Closed
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chore(release): Release beta.8 angular/angularfire
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@alixaxel @cartant