duanrong5927
2013-11-29 22:07
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golang GET请求json类型在运行时错误

im trying to write a small app using usa today's RESTful api in golang, but it seems i have an error in type conversion when trying to parse the GET request from the api. My program compiles which makes me think the types are right, but at run time my program crashes

i got a good idea how to map incoming json in which you don't have premade structures for using the type interface {} from http://blog.golang.org/json-and-go

here's what my golang code looks like:

// get request to API
resp, err := http.Get("http://api.usatoday.com/open/articles/topnews/home?count=10&days=0&page=0&encoding=json&api_key=myApiKey")

if(err == nil){
    body, err := ioutil.ReadAll(resp.Body)
    if(err == nil) {
        var data interface{}
        json.Unmarshal(body, &data)

        var m = data.(map[string] []interface{})            
        var articles = m["stories"]
        var newArticle interface {}

        for newArticle = range articles {
            var n = newArticle.(map[string] string)

            fmt.Printf("<h2>Title: " + n["title"] + "</h2>")
            fmt.Printf("<p>description: " + n["description"] + "</p>")
            fmt.Printf("<p>link to article: " + n["link"] + "</p>")
        }

    } else {
        fmt.Println(err)
    }

} else {
    fmt.Println(err)
}

and here's a small example of the get request response looks like

{
    "stories": [{
        "description": "Despite the fact that shoppers descended upon stores after giving thanks, Black Friday wasn't without its share of brawls.",
        "guid": [{
            "isPermalink": "true",
            "value": "http:\/\/apidata.usatoday.com\/story\/news\/nation-now\/2013\/11\/29\/black-friday-police-violence\/3783467\/?kjnd=Pvzhnh75%2BZ3dnzxHVv571HQOfzKReZECsSPCBGnAiXlbHijpqdc3TQoe4dYfzVlB-8d81f9e3-0b56-421e-a5da-121f9eb83de3_E50GPTZL1%2FYloJsxpxSnp8AhoO2O9prQtDTYiwN3sbV0SfQ5wriH1zooo6XgNPTr"
        }],
        "link": "http:\/\/apidata.usatoday.com\/story\/news\/nation-now\/2013\/11\/29\/black-friday-police-violence\/3783467\/?kjnd=LOCSg6KVoQR3pwnZyGmcgcDZXwce0MwglPkURuQ%2BzMkUdNzQ2GXJr%2FPfLCl4Hf38-8d81f9e3-0b56-421e-a5da-121f9eb83de3_Zp5d44u%2F3U2IkXWRbNP0OwyXjRkEgShxoJC0wp7%2FOJoFPCI979Zw4qgNkWkOG1x1",
        "pubDate": "Fri, 29 Nov 2013 02:57:43 GMT",
        "title": "Black Friday frenzy leads to reports of violence"
    }, {
        "description": "President Obama's law faces hurdles beyond the Supreme Court case on the birth control mandate.",
        "guid": [{
            "isPermalink": "true",
            "value": "http:\/\/apidata.usatoday.com\/story\/news\/politics\/2013\/11\/29\/supreme-court-obamacare-lawsuits-irs\/3760811\/?kjnd=sCqadf244XkWTNcS0zAI%2Ba25XsnxwAX3ahu8NP0bzKdU4Kx31rJsa0cWlhvnwMl8-8d81f9e3-0b56-421e-a5da-121f9eb83de3_wtrtyHNPao7CqrB0IR7%2Bj3GFwJMhSYFSrOrrGZCkX2BStipIyyDtQoTLLFCGoLj0"
        }],
        "link": "http:\/\/apidata.usatoday.com\/story\/news\/politics\/2013\/11\/29\/supreme-court-obamacare-lawsuits-irs\/3760811\/?kjnd=Be2GdDxc2cZdIOPiCpcL9vz%2FFvmT859xSGoVutxwurqJ%2FCwvTt8vjs2s9MHzI1hO-8d81f9e3-0b56-421e-a5da-121f9eb83de3_88mb%2BwbADj1MvtG9%2BiYMhVS43CRGBEVdn0v5QJsORviARUA3qR0iE9LBr7NpNrT7",
        "pubDate": "Fri, 29 Nov 2013 11:12:08 GMT",
        "title": "Long-shot legal challenges to health care law abound"
    }
    }]
}

AND finally here's what the error looks like at runtime

panic: interface conversion: interface is map[string]interface {}, not map[string][]interface {}

not really sure how i should go about this, so anyone with pre-existing knowledge of working with RESTful api's in golang that would have some insight would be greatly appreciated!

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3条回答 默认 最新

  • duanlei1957 2013-11-29 23:58
    最佳回答

    i ended up fixing it using some structures that matched the json objects... which was kind of a pain.

    here it is if anyone ever wants to use this api in golang

    type stories struct {
        Stories []story
    }
    type story struct {
        Description string
        Guid []guid
        Link string
        PubDate string
        Title string
    }
    type guid struct {
        IsPermalink string
        Value string
    }
    
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