mongodb update添加每个地图结构的值

Question

There is a map data {"a": 2, "c": 4: "d": 0}, and a document in MongoDB:

{
    ...
    Score: {
        "a": 1,
        "b": 2,
        "c": 0,
    }
}

The updated document:

{
    ...
    Score: {
        "a": 3,
        "b": 2,
        "c": 4,
        "d": 0,
    }
}

Is what I wanted, now this works well:

bson.M{"$inc": bson.M{"Score.a": 2,....}},

How can I use a map without knowing its keys to update the document in MongoDB? Map to struct? Or use MongoDB .map function?

Answer 1

If you have the map value, you know its keys, you can loop over them, and build the "dynamic" update document manually.

This is how it could look like:

m := map[string]int{
    "a": 2,
    "c": 4,
    "d": 0,
}

incDoc := bson.M{}
for k, v := range m {
    incDoc["Score."+k] = v
}
updateDoc := bson.M{"$inc": incDoc}

Printing the result with

fmt.Printf("%#v
", updateDoc)

Output would be:

bson.M{"$inc":bson.M{"Score.d":0, "Score.a":2, "Score.c":4}}