How to Parse a JSON Array of Dynamic Key-Value Pairs in Go?

Parsing a JSON Array into a Data Structure in Go

When working with JSON data in Go, it's essential to understand the appropriate data structures for different JSON formats. In this case, we are dealing with a JSON array of dynamic key-value pairs.

Problem:

You are attempting to parse a JSON file containing an array of JSON objects. However, using a simple map[string]string to represent the data results in an error:

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

type data map[string]string

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

Solution:

To correctly parse the JSON array, you need to define a data structure that represents the array of objects. This can be achieved using a custom type that embeds a slice of maps.

type mytype []map[string]string

Code:

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)
}

Example:

For the provided JSON file:

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

The output of the code would be:

[{map[a:1]} {map[b:2]} {map[c:3]}]

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