JSON封送处理产生意外结果

Here is a Go Playground demonstrating my problem: http://play.golang.org/p/2fq3Fg7rPg

Essentially, I am trying to JSON marshal a struct containing a custom type wrapping json.RawMessage. When using CustomType.MarshalJSON() I get the expected results, but just calling json.Marshal on my full struct does not work as expected. See the playground link for a concrete example.

What is causing this difference?

Is there a way to have json.Marshal work as I expect it to?

Your code works fine, you just have one little bug.

// MarshalJSON returns the *j as the JSON encoding of j.
func (j JsonText) MarshalJSON() ([]byte, error) {
    return j, nil
} // note i modified this so the receiver isn't a pointer

Your code didn't work because this is your definition of your datatype that wraps JsonText;

// Example struct I want to marshal and unmarshal
type TestData struct {
    Field1 JsonText `json:"field_1"`
}

But only the *JsonText type implements the marshaler interface in your code. So you can change the types in either place ( I did in the MarshalJSON() ) but they need to be consistent.

In the playground; http://play.golang.org/p/NI_z3bQx7a