Unmarshalling JSON Arrays with Mixed Data Types

The task of unmarshalling JSON arrays containing values of different data types can often pose a challenge. For instance, consider the following JSON array:

{["NewYork",123]}

Issue:

Firstly, it's crucial to note that the provided JSON is syntactically incorrect. JSON objects require keys for each value, so a correct representation would be either {"key":["NewYork",123]} or simply ["NewYork",123].

Furthermore, when dealing with JSON arrays comprised of multiple data types, the problem arises when Go arrays necessitate a specified type. This can leave you wondering how to handle such situations.

Solution:

The key to tackling this issue is to employ the type interface{}. It allows you to handle values of varied types without the need for explicit type conversion. Here's a code example that demonstrates how it works:

import (
    "encoding/json"
    "fmt"
)

const j = `{"NYC": ["NewYork",123]}`

type UntypedJson map[string][]interface{}

func main() {
    ut := UntypedJson{}
    fmt.Println(json.Unmarshal([]byte(j), &ut))
    fmt.Printf("%#v", ut)
}

In this example, we use UntypedJson as a custom type that maps strings to slices of interface{}. By utilizing the interface{} type, we can effortlessly handle mixed data types within the JSON array.

The output of the program would be:

<nil>
map[string][]interface{}{"NYC": \["NewYork" 123]}

Conclusion:

By leveraging the interface{} type, this approach enables you to effectively unmarshal JSON arrays with various data types.