User search with Golang mgo

Getting a string as input (from a user search), I am trying to construct a bson.M object for mgo to search through the mongo database and find x number of items.

Something like this

<!-- language: lang-golang -->

func Search (w http.ResponseWriter, r *http.Request) {
    q := r.FormValue("q")
    filter := bson.M{}
    // magic happens here 
    // do db connection stuff
    things := []*thing{}
    err := db.Find(&filter).Limit(10).All(&things)
    // check error, send things, etc
}

What I need the search to be based on is

• ignore case (I found this answer which takes me part of the way)
• the title in the stored data must, somewhere, include each of the words in the q.

So for instance if the stored data looks like {title: "abcde"}, then

• Abc will match
• de Bc will match
• ac will not match

Edit: Solution

I finally figured it out. The magic part looks like this:

q := r.FormValue("q")
qs := strings.Split(q, " ")
and := make([]bson.M, len(qs))
for i, q := range qs {
    and[i] = bson.M{"title": bson.M{
        "$regex": bson.RegEx{Pattern: ".*" + q + ".*", Options: "i"},
    }}
}
filter := bson.M{"$and": and}

The mongo filter can take regex, for example;

        bson.M{"title": bson.M{"$regex": bson.RegEx{Pattern: title, Options: "i"}}}

So in this case the title variable would be something like; .*abc*.. The Options: "i" enables case insensitivity.

As for matching the substring (scenario 2) I am not sure how to achieve within regex.

Simple use this,

wordOffset := q
selector:= bson.M{"title": bson.M{"$regex": wordOffset}}