How Can I Unmarshal JSON Arrays with Mixed Data Types in Go?

Unmarshaling JSON Arrays with Mixed Value Types

Unmarshalling a JSON array containing values of varying types can pose a challenge in Go due to the requirement for explicit type definition in Go arrays.

Case Study:

Consider the following invalid JSON example:

["NewYork", 123]

An attempt to decode this array into a Go array would fail because the Go array requires a fixed type, which is unknown in this case.

Solution:

To overcome this limitation, Go provides the interface{} type, which allows for the storage of values of any type. By utilizing interface{}, it becomes possible to unmarshal JSON arrays containing mixed value types, as demonstrated below:

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 define a custom type UntypedJson as a map of string keys to slices of interface{}. The JSON array is then unmarshaled into the UntypedJson instance. The fmt.Printf statement displays the unmarshaled data, which contains the mixed values from the JSON array.

By utilizing the interface{} type, it becomes possible to unmarshal JSON arrays containing values of varying types, providing a more flexible and versatile solution for complex data scenarios.

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