Suppose we are debugging some Go code, and somewhere in an external dependency we encounter this line:

return json.Marshal(foo)

We want to set a breakpoint and use IntelliJ's "Evaluate Expression" to inspect the JSON being produced. However, this doesn't work:

• If we evaluate the expression json.Marshal(foo), we only get to see the byte array.
• Evaluating string(json.Marshal(foo)) doesn't work because json.Marshal returns two values, the byte array and an error.
• There is no way in Go to access one of the return values directly.

So how can I use "Evaluate Expression" to achieve my goal of just printing the produced JSON string when I'm not able to change the underlying source code?

CodePudding user response：

you can print the returned bytes as a string

bytes, err := json.Marshal(foo)
// check error here
fmt.Println(string(bytes))

update based on comments

You can't change the byte slice in the debugger to a string without changing the source code.