CODEWITHSUNDEEP
go
FuriousGeorge
FuriousGeorge

Reputation: 4681

Golang range type conversion

I'm very confused by this code that I have:

docs, ok := foo.([]interface {})
if !ok{ panic("assertion failed") }

fmt.Println("The type of docs: ", reflect.TypeOf(docs))
for _, doc := range docs {
    fmt.Println("Doc Type: ", reflect.TypeOf(doc))
}

The output when I run this is:

The type of docs: []interface {}
Doc type: bson.D

I don't get it. I type assert foo to []interface{} and store it in docs. That works as expected, but then in the loop, the first thing I print out is the type of doc and it says it's bson.D. How is it not interface {}?? I even changed the name of doc to bar thinking maybe it was a scoping issue or something, but I get the same results.

Upvotes: 1

Views: 1151

Answers (1)

siritinga
siritinga

Reputation: 4231

TypeOf documentation says: TypeOf returns the reflection Type of the value in the interface{}. TypeOf(nil) returns nil.

So doc is of type interface{} but TypeOf returns its "true" type.

Upvotes: 3

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