Golang parse JSON array into data structure

40,877

Solution 1

It's because your json is actually an array of maps, but you're trying to unmarshall into just a map. Try using the following:

type YourJson struct {
    YourSample []struct {
        data map[string]string
    } 
}

Solution 2

Try this: http://play.golang.org/p/8nkpAbRzAD

package main

import (
    "encoding/json"
    "fmt"
    "io/ioutil"
    "log"
)

type mytype []map[string]string

func main() {
    var data mytype
    file, err := ioutil.ReadFile("test.json")
    if err != nil {
        log.Fatal(err)
    }
    err = json.Unmarshal(file, &data)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(data)
}

Solution 3

you can try the bitly's simplejson package
https://github.com/bitly/go-simplejson

it's much easier.

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40,877
Kiril
Author by

Kiril

Keep it simple

Updated on January 26, 2020

Comments

  • Kiril
    Kiril over 4 years

    I am trying to parse a file which contains JSON data:

    [
      {"a" : "1"},
      {"b" : "2"},
      {"c" : "3"}
    ]
    

    Since this is a JSON array with dynamic keys, I thought I could use:

    type data map[string]string
    

    However, I cannot parse the file using a map:

    c, _ := ioutil.ReadFile("c")
    dec := json.NewDecoder(bytes.NewReader(c))
    var d data
    dec.Decode(&d)
    
    
    json: cannot unmarshal array into Go value of type main.data
    

    What would be the most simple way to parse a file containing a JSON data is an array (only string to string types) into a Go struct?

    EDIT: To further elaborate on the accepted answer -- it's true that my JSON is an array of maps. To make my code work, the file should contain:

    {
      "a":"1",
      "b":"2",
      "c":"3"
    }
    

    Then it can be read into a map[string]string