Convert Json.Number into int/int64/float64 in golang

go go-interface
KuZon picture KuZon · Jan 25, 2018 · Viewed 18k times · Source

I have a variable data, which is an interface. When I print its type I get it as json.Number. How do I type cast to int/int64/float64

If I try data.(float64), it ends up with panic error 

panic: interface conversion: interface {} is json.Number, not float64

Answer

Ilayaraja picture Ilayaraja · Jan 25, 2018

Check this documentation to know the available methods on json.Number: https://golang.org/pkg/encoding/json/#Number

f, err := data.(json.Number).Float64()

Related questions

Type converting slices of interfaces

I'm curious why Go does't implicitly convert []T to []interface{} when it will implicitly convert T to interface{}. Is there something non-trivial about this conversion that I'm missing? Example: func foo([]interface{}) { /* do something */ } func main() { var a []string = []string{"…

Read More
Empty Interfaces in Golang

Edit: This is not the right way to use interfaces in Go. The purpose of this question is for me to understand how empty interfaces work in Go. If all types in Go implement interface{} (empty interface), why can't I …

Read More
In Go, how do I check a value is of (any) pointer type?

I have a slice of interface{} and I need to check whether this slice contains pointer field values. Clarification example: var str *string s := "foo" str = &s var parms = []interface{}{"a",1233,"b",str} index := getPointerIndex(parms) fmt.Println(index) // …

Read More