extract JSON from golang's echo request

Question

I'm using Echo to build a minimalist server in Golang.

In, Echo one can bind an incoming JSON request payload to a struct internally and access the payload.

However I have a scenario wherein I know only 3 fields of the incoming JSON request payload, and the bind doesn't work in this case.

How do I still access the 3 fields that I care about ? If I cannot do this in Echo, can you recommend me a JSON decoder that works with Echo's context structure?

Answer 1

This is how I did it:

json_map := make(map[string]interface{})
err := json.NewDecoder(c.Request().Body).Decode(&json_map)
if err != nil {
    return err
} else {
    //json_map has the JSON Payload decoded into a map
    cb_type := json_map["type"]
    challenge := json_map["challenge"]

Answer 2

I'm not the most experienced with Echo, but to my knowledge the bind won't work in this case. @elithar provided what may be a good answer to your question in another thread:

---

From: Golang Json single value parsing

You can decode into a map[string]interface{} and then get the element by key.

data := make(map[string]interface{})
err := json.Unmarshal(content, &data)
if err != nil {
   return nil, err
}

price, ok := data["ask_price"].(string); !ok {
    // ask_price is not a string
    return nil, errors.New("wrong type")
}

// Use price as you wish

Structs are often preferred as they are more explicit about the type. You only have to declare the fields in the JSON you care about, and you don't need to type assert the values as you would with a map (encoding/json handles that implicitly).

---

You should be able to grab your context's data and extract the fields you want in this manner.

Answer 3

Using Golang's Echo framework, you extract data from JSON like this

Sample Json

{
    "username": "Super User",
    "useremail": "[email protected]"
}

Code

import (
    "github.com/labstack/echo"
)

func main() {
    my_data := echo.Map{}
    if err := echoCtx.Bind(&my_data); err != nil {
        return err
    } else {

        username := fmt.Sprintf("%v", my_data["username"])
        useremail := fmt.Sprintf("%v", my_data["useremail"])
    }
}

Answer 4

I created a custom function that retrieves raw json body and returns a nil if no values present otherwise in returns a map[string]interface{}

import (
   "encoding/json"
   "github.com/labstack/echo/v4"
   "github.com/labstack/gommon/log"
)
 
 
func GetJSONRawBody(c echo.Context) map[string]interface{}  {

     jsonBody := make(map[string]interface{})
     err := json.NewDecoder(c.Request().Body).Decode(&jsonBody)
     if err != nil {

         log.Error("empty json body")
         return nil
     }

    return jsonBody
}

Answer 5

here is the simple solution

func UnwantedJSONHandler(c echo.Context) error {
    b, _ := io.ReadAll(c.Request().Body)
    var r RequestDataAssumedStruct
    if err := json.Unmarshal(b, &r); err != nil {
        log.Println(err.Error())
        return err
    }
    log.Println(r)
}

We just took the byte data from the request body and unmarshaled the JSON. I have seen some solution given by the others but it seems that's a long way so i still put the answer even though it is marked as solved