Backbone model fetch return blank JSON,model dont trigger change event?

when the model fetch from server an开发者_Python百科d return a blank JSON ( []),the model did not change its attribute,so how can I know if the model is return same data , or return blank data?

You can set callback function in .fetch() options so you will know when request will finished. Or you can extend fetch method or add another one with functional you want/need.