Simplest way to return literal JSON using gin gonic

Question

I am learning Go by building a simple API interface for a web server. I want to return a simple message in JSON, when a default route is hit.

So far, reading online, this is the easiest way to return a literal JSON string, and encode it and send it to the user.

func GetDefault(c *gin.Context)  {
    jsonData := []byte(`{"msg":"this worked"}`)

    var v interface{}
    json.Unmarshal(jsonData, &v)
    data := v.(map[string]interface{})  

    c.JSON(http.StatusOK,data)
}

Is this the most efficient / fastest way to do it?

in node.js and express, I would do something like:

return res.status(200).json({"msg":"this worked"});

Whats the best way to do this in Go + Gin?

Answer 1

you can use the gin.H struct on you response:

c.JSON(http.StatusOK, gin.H{"msg":"this worked"})

Answer 2

One option is to use Context.Data() where you provide the data to send (along with the content type):

func GetDefault(c *gin.Context)  {
    jsonData := []byte(`{"msg":"this worked"}`)

    c.Data(http.StatusOK, "application/json", jsonData)
}

You may also use a constant for the content type:

func GetDefault(c *gin.Context)  {
    jsonData := []byte(`{"msg":"this worked"}`)

    c.Data(http.StatusOK, gin.MIMEJSON, jsonData)
}

If your data is availabe as a string value and is big, you can avoid converting it to []byte if you use Context.DataFromReader():

func GetDefault(c *gin.Context) {
    jsonStr := `{"msg":"this worked"}`

    c.DataFromReader(http.StatusOK,
        int64(len(jsonStr)), gin.MIMEJSON, strings.NewReader(jsonStr), nil)
}

This solution also works if you have your JSON as an io.Reader, e.g. an os.File.