CODEWITHSUNDEEP
angularjscachingpromise
Jaap
Jaap

Reputation: 3220

angularjs $http cache, will it cache server errors

In angular $http.get(url, {cache:true}) will nicely cache server responses. But what does the cache do when the GET request to the server fails? This could be a temporary connection issue or a server response like a timeout.

Suppose I handle the error and display a retry button, will a subsequent call to $http.get(url, {cache:true}) retry the server or will it give me a failed promise from the cache?

Upvotes: 1

Views: 485

Answers (1)

Benjamin Gruenbaum
Benjamin Gruenbaum

Reputation: 276306

If multiple requests are made to the same GET url the cache will cause there to only be one request. Quoting the documentation:

If there are multiple GET requests for the same URL that should be cached using the same cache, but the cache is not populated yet, only one request to the server will be made and the remaining requests will be fulfilled using the response from the first request.

However, when that request returns if the status code is not successful it will not be cached (it will be removed from the cache).

We can see this in the source code:

/**
   * Callback registered to $httpBackend():
   *  - caches the response if desired
   *  - resolves the raw $http promise
   *  - calls $apply
   */
  function done(status, response, headersString, statusText) {
    if (cache) {
      if (isSuccess(status)) {
        cache.put(url, [status, response, parseHeaders(headersString), statusText]);
      } else {
        // remove promise from the cache
        cache.remove(url);
      }
    }

So in short - Angular will not cached 'failed' requests - that is: requests with a non-success status code.

Upvotes: 5

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