Why Does JSON Unmarshaling an Array into a Go Struct Cause a Panic?

Panic: JSON Unmarshal Array into Go Struct

When attempting to parse data from a JSON API, you encountered the error: "panic: json: cannot unmarshal array into Go value of type main.Structure." The issue arises when unmarshalling a JSON array into a Go struct.

Your Code:

type Structure struct {
        stuff []interface{}
}

func main() {
        // ...

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

Expected Result:

You expected the code to return a list of interface objects.

Actual Result:

Instead, you received an error indicating that the JSON array could not be unmarshalled into the Structure Go value.

Solution:

To resolve this issue, consider two approaches:

1. Unmarshal to a Slice:

   Replace the line:

   decoded := &Structure{}

   with:

   var data []interface{}

   This will unmarshal the JSON array to a slice of interfaces.

2. Unmarshal to a Slice of Structs:

   Create specific structs for the response data structure. For example:

   type Tick struct {
     ID string
     Name string
     Symbol string
     Rank string
     Price_USD string
   }

   Then, unmarshal to a slice of these structs:

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

The above is the detailed content of Why Does JSON Unmarshaling an Array into a Go Struct Cause a Panic?. For more information, please follow other related articles on the PHP Chinese website!