Angular HTTP响应长度未定义

Question

I'm using Angular to interact with jQuery Mobile and create several pages but am running into an issue with the $http service when connecting to my JSON requests. I have a few arrays I'm populating with functions and can bring back data to my pages, except at times I will get errors like this

Cannot read property 'length' of undefined

My code looks like this:

$http.jsonp(url).success(function(data) {
  for (i=0; i<data.PROJECT.length; i++)
      $scope.ProjectList.push( { id:data.PROJECT[i].PROJECT_CODE, name:data.PROJECT[i].PROJECT_DESC } );
});

My For loop is where it will randomly crash. I've also tried a "then" approach:

var request = $http.jsonp(url);
return request.then(function(request) { return request.data.PROJECT; }, handleError );

Same error (or no error and blank results). What am I doing wrong? I have each API call in it's own function so it shouldn't be reusing objects (might it be appending them though?). This is part 1; part 2 is separating my code into controller/service - I'm getting these same errors when I do that as well.

UPDATE

I've created a jsFiddle here for showing how the values will populate SOMETIMES - run it a few times and you'll notice the arrays take turns returning empty. If you were able to see the console.log output you would see ProjectList contains the resultset of EquipList (in addition to ProjectList) and vice versa.

Answer 1

Sorry SO doesn't let me comment yet :-S so I'll answer here. Based on your

... except at times I will get errors like this

it sounds like the URL you are calling isn't responding correctly. The code looks good assuming your JSON response looks like this:

{
  "PROJECT": [ 
    { "PROJECT_CODE": ..., "PROJECT_DESC": ... },
    ...
  ]
}

However if you have this intermittently I would guess that the server responds with something other than this structure above, however still sending a HTTP status 200 OK .

Try to monitor your network requests and see what the actual response is, or do a console.log of data inside the success function.

--- EDIT

As I thought it mainly is a API issue. The API seems to respond sometimes with the correct list(s), but often times (at least now) it is responding with a HTTP 200 OK , but without any data ( Content-Length: 0 ). Your fiddle doesn't really show when it's loading, so I updated your code a little bit here: http://jsfiddle.net/gce4ns9a/15/ . The reason why you never have that 'This never shows up' is because the API responds with 'OK' instead of some error code such as HTTP 500 Inter server error or something similar.

I hope that helps.