dongyi7966
dongyi7966
2016-04-29 16:35
浏览 327

jQuery Ajax不会返回数据(解析错误),但Postman成功

I've been using Postman to test my REST API (written in Go). Now is the moment of truth, connecting to the front end and I've hit a hiccup. I'm using jQuery.ajax to send a GET to my server, which should then send me back the response.

Note: Going to postman and sending a GET request to http://REMOTE_IP:8000/users/ returns the information I'm looking for, an array of User objects (JSON). It confuses me that it would work for Postman, but not jQuery.

jQuery Get

$.ajax({
    url: "http://REMOTE_IP:8000/users/",
    type: "GET",
    dataType: 'jsonp',
    contentType: 'application/json',
    success: function(data) {
        console.log(data);
    },
    error: function(jqXHR, status, err) {
        console.log(jqXHR);
        console.log(status);
        console.log(err);
    }
});

Go Backend

func GetUsersRoute(w http.ResponseWriter, r *http.Request) {
    var queryResult []models.User

    queryErr := Config.Users.Find(bson.M{}).All(&queryResult)
    resultsJSON, jsonErr := json.Marshal(queryResult)

    handleQueryAndJsonErrors(w, queryErr, jsonErr)

    // added these for cors, not sure they do anything helpful
    w.Header().Set("Content-Type", "application/json; charset=UTF-8")
    w.Header().Set("Access-Control-Request-Headers", "*")

    w.WriteHeader(http.StatusOK)
    w.Write(resultsJSON)
}

I also have a logger attached to my go backend, and here are the request method and request URI that are printed out when I make the request:

GET /users?callback=jQuery223019655483671137586_1461946990647&_=1461946990648

Here are some articles I found useful:
The data which jquery $.ajax function return could not be parse to json

https://github.com/codegangsta/martini-contrib/blob/master/cors/cors.go

https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS#Access-Control-Allow-Methods

Here are the errors returned with jQuery's err callback: enter image description here

What could be going wrong?

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2条回答 默认 最新

  • dongsou8980
    dongsou8980 2016-08-10 17:17
    已采纳

    # Answer

    I found a nice go library that handles the cross-origin problems I was having, meaning I didn't have to rely on jsonp. Here's the revised go code:

    Using the CORS Handler

    handler := cors.Default().Handler(r)
    err := http.ListenAndServe(port, handler)
    
    if err != nil {
        panic(err)
    }
    

    Revised handler

    func GetUsersRoute(w http.ResponseWriter, r *http.Request) {
        var queryResult []models.User
    
        queryErr := Config.Users.Find(bson.M{}).All(&queryResult)
        resultsJSON, jsonErr := json.Marshal(queryResult)
    
        handleQueryAndJsonErrors(w, queryErr, jsonErr)
    
        w.Header().Set("Content-Type", "application/json; charset=UTF-8")
        w.WriteHeader(http.StatusOK)
        w.Write(resultsJSON)
    }
    

    Calling from the frontend

    var extension = 'users/',
        requestPath = serverAddress + extension;
    
    $.ajax({
        url: requestPath,
        type: 'GET',
        dataType: 'json',
        contentType: 'application/json',
        success: successCall,
        error: failCall
    });
    
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  • douyun6781
    douyun6781 2016-04-29 18:20

    First check whether your server can handle JSONP requests by using following tests.

    http://REMOTE_IP:8000/users?callback=myFunction
    

    The response instead of this (it will look like this if it doesn't support JSONP):

    { "thing": "value" .... }
    

    Should look like this (again, if it supports JSONP):

    myFunction({ "thing": "value" .... });
    
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