dtf579777
2019-08-13 06:09
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如何读取多个json文件

I am trying to read json data from multiple json files. I am not sure how I read each files and concatenate all results

There json files name are test1.json, test2.json test3.json..etc with the same data structure but I am having an issue read then all and my code seems to only show the last one. I have concatenated a string based on the file name but seems to not working for me.

type Book struct {
    Id    string `json: "id"`
    Title string `json: "title"`
}

func main() {
    fileIndex := 2 // three json files. All named test1.json, test2.json and test3.json

    var master []Book

    for i := 0; i <= fileIndex; i++ {
        fileName := fmt.Sprintf("%s%d%s", "test", fileIndex, ".json")

        // Open jsonFile
        jsonFile, err := os.Open(fileName)

        defer jsonFile.Close()

        byteValue, _ := ioutil.ReadAll(jsonFile)
        fmt.Println(byteValue)
        var book []Book

        json.Unmarshal(byteValue, &book)
        fmt.Println(book) // all print shows the test3.json result 
    }
}

I need to be able to read all three json files and hoping to concatenate all results. Can anyone help me? Thank you!

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1条回答 默认 最新

  • dozr162106 2019-08-13 06:26
    已采纳

    You are using fileIndex while generating the filename instead of using i in the for loop. The code after the changes would be :

    type Book struct {
        Id    string `json: "id"`
        Title string `json: "title"`
    }
    
    func main() {
        fileIndex := 2 // three json files. All named test1.json, test2.json and test3.json
    
        var master []Book
    
        for i := 0; i <= fileIndex; i++ {
            fileName := fmt.Sprintf("%s%d%s", "test", i, ".json")
    
            // Open jsonFile
            jsonFile, err := os.Open(fileName)
    
            defer jsonFile.Close()
    
            byteValue, _ := ioutil.ReadAll(jsonFile)
            fmt.Println(byteValue)
            var book []Book
    
            json.Unmarshal(byteValue, &book)
            fmt.Println(book)
        }
    }
    

    Also, you can do something like master = append(master, book) inside the for loop to finally get all JSON content in master

    已采纳该答案
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