Backbone.js + Rest. Collection is not populated af

问题:

I'm new in Backbone. So I'm trying to fetch data from REST service.

this is my simple code:

$(function () {

    var Entity = Backbone.Model.extend({
        url: function() {
            return 'http://localhost:8080/rest/entity/'+this.id;
        }
    });

    var EntityList = Backbone.Collection.extend({       
        model: Entity,
        url: 'http://localhost:8080/rest/entity'
    });

    var entityList = new EntityList();

    entityList.fetch();

});

my rest service returns next JSON:

[{"id":1387,
  "version":3,
  "entityName":"entity01",
  "entityLabel":"Entity01",
  "entityPluralLabel":"Entity01",
  "attributes":
     [{"id":1425,
       "slot":"D001",
       "version":0,
       "attributeName":"dfield",
       "attributeType":
          {"id":7,
           "description":"Date",
           "attributeType":"date",
           "databaseType":"DATE"
          },
       "options":[],
       "order":2,
       "attributeLabel":"dField",
       "checked":null
      },
      {"id":1424,
       "slot":"S001",
       "version":0,
       "attributeName":"txfield",
       "attributeType":
          {"id":1,
           "description":"Textbox",
           "attributeType":"textbox",
           "databaseType":"STRING"
          },
       "options":[],
       "order":1,
       "attributeLabel":"txField",
       "checked":null
      }
     ]  
 },
 {"id":1426,
  "version":3,
  "entityName":"entity02",
  "entityLabel":"Entity02",
  "entityPluralLabel":"Entity02",
  "attributes":
     [{"id":1464,
       "slot":"D001",
       "version":0,
       "attributeName":"dfield",
       "attributeType":
          {"id":7,
           "description":"Date",
           "attributeType":"date",
           "databaseType":"DATE"
          },
       "options":[],
       "order":2,
       "attributeLabel":"dField",
       "checked":null
      }
     ]
 }
]

In debugger I see that request was sent to REST service and response was recieved, how can I see if entityList collection is populated with recieved data or not? In debugger entityList.models is empty after entityList.fetch();

Am I on right way or somthing is wrong with my code?

回答1:

I think you are on the right way. But because Backbone.Collection.fetch() is async, you should check value of entityList.models not right after the method call, but in success callback of fetch.

That is, this code will say that models list is empty:

entityList.fetch();
console.log(entityList.models); // => 0 (collection being fetched)

while this code will print number of models in the collection when it have been populated:

entityList.fetch({success: function(){
    console.log(entityList.models); // => 2 (collection have been populated)
}});