解决无效的内存地址或nil指针取消引用

Question

Banging my head on this one. I can't get an HTTP Response to assign to a struct.

I have my structs set up like so:

type DataConnect struct {
    Response *Response
}

type Response struct {
    response []byte
    errors   []string
}

Then the function in question is laid out like so (trimmed for readability):

137 func (d *DataConnect) send() bool {

    ...

154    out, err := ioutil.ReadAll(resp.Body)
155    if err != nil {
156        fmt.Println(err)
157    }
158
159    fmt.Printf("%s
", out) // THIS WORKS
160    d.Response.response = out // THIS DOES NOT WORK
161 }

Doing that results in the following error:

panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x36532]

goroutine 1 [running]:
github.com/DataConnect.(*DataConnect).send(0xc2000af4a0, 0x232a00)
github.com/DataConnect/DataConnect.go:160 +0xc22

Now if I change DataConnect.Response.response to type interface{} I can save successfully to it, however I need it in []byte as later I will be doing a json.Unmarshal on the content.

Does anybody have any idea why this isn't working?

Answer 1

I suspect either d is nil or d.Response is nil on line 160. If that is true, you need to decide if that is appropriate and change your code if it is not.