How to convert interface{} to int?

Question

I'm trying to get a value from a JSON and cast it to int but it doesn't work, and I don't know how to do it properly.

Here is the error message:
...cannot convert val (type interface {}) to type int: need type assertion

And the code:
    var f interface{}
    err = json.Unmarshal([]byte(jsonStr), &f)
    if err != nil {
        utility.CreateErrorResponse(w, "Error: failed to parse JSON data.")
        return
    }

    m := f.(map[string]interface{})

    val, ok := m["area_id"]
    if !ok {
        utility.CreateErrorResponse(w, "Error: Area ID is missing from submitted data.")
        return
    }

    fmt.Fprintf(w, "Type = %v", val)   // <--- Type = float64
    iAreaId := int(val)                // <--- Error on this line.
    testName := "Area_" + iAreaId      // not reaching here

Gopher · Accepted Answer

Instead of iAreaId := int(val) you want a type assertion: iAreaId := val.(int) iAreaId, ok := val.(int) // Alt. non panicking version The reason why you cannot convert an interface typed value are these rules in the referenced specs parts: Conversions are expressions of the form T(x) where T is a type and x is an expression that can be converted to type T.

Go Language

Similar Questions

Does Golang support variadic function?

How to cast any int value to int64 in type switch in Go?

How to crate for loop of two variables in Go?

On a mission to build Next-Gen Community Platform for Developers

Facebook

Twitter

Linkedin

Instagram