How to assert a primitive.m to a map[string]string

Question

I am working with MongoDB in my Go application, and pull some data out and store it in a bson.M (which . Here is an example, of getting the bson.M object from the DB and then printing it (let's call this object data):

[map[_id:ObjectID("XXXXXXX") address:XX decimal:18 providers:map[currency:value] symbol:LINK]

Which looks correct to me.

I think want to loop over the map in the providers field (as you can see, it's a map in there as well). I've done a few attempts, but each time I am blocked.

Due to what I've read in the docs here and the testing I've done, it looks like a bson.M and primitive.M are the same, and they are each treated as a map[string]interface{}.

When I attempted to assert it to a map[string]string I go a panic error:

// code run
data["providers"].(map[string]string)

//error received
panic: interface conversion: interface {} is primitive.M, not map[string]string

The reason for this, is I want to loop over the providers field, and when I try to loop as-is, I get this error:

// code to run
for key, provider := range data["providers"] {...}

// error received
cannot range over data["providers"] (map index expression of type interface{})

I have read that I might need to do something with marshaling and decoding, but I feel like I'm just missing a step as to why I would need to do those, or how they would help.

In any case to summarize:

1. How does one loop over a primitive.M/bson.M/map[string]interface{}?

2. How does one convert a primitive.M/bson.M/map[string]interface{} to a map[string]string?

It looks like I might be trying to do the opposite of this entry, and it looks like this entry is giving me conflicting information. Hoping to edit the question as I understand more what my real problem is. Thank you!

Answer 1

Speaking with Burak Serdar helped give us the answer! You have to assert the data["providers"] to a primitive.M

for key, provider := range data["providers"].(primitive.M){...}

Key thing to note: primitive.M is handled like a map[string]interface{}

As Burak Serdar mentioned, I cannot assert this instance of a primitive.M to a map[string]string, because the interface in map[string]interface{} is of type primitive.M. So instead, I have to assert the providers object to a primitive.M object, and then I can loop over it normally.

I cannot convert a primitive.M to a map[string]string