Why Does JSON Unmarshal Fail When Mapping Arrays to Go Structs?

Unable to Unmarshal JSON Array into Go Structure

In an attempt to parse data from a JSON API, a programmer encountered the error: "panic: json: cannot unmarshal array into Go value of type main.Structure."

Problem Excerpt:

type Structure struct {
        stuff []interface{}
}

...

decoded := &Structure{}
err = json.Unmarshal(body, decoded)

Expected Result:

A list of interface objects.

Actual Result:

panic: json: cannot unmarshal array into Go value of type main.Structure

Solution:

The issue arises when trying to unmarshal a JSON array into a Go struct. To resolve this, one can either:

• Unmarshal into a Slice:

var data []interface{}
err = json.Unmarshal(body, &data)

• Unmarshal into a Slice of Structs:

type Tick struct {
     ID string
     Name string
     ... and so on
}

var data []Tick
err = json.Unmarshal(body, &data)

By customizing the struct type to match the structure of the response data, the unmarshaling process will successfully parse the JSON array.

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