如何在从arangodb中的边缘集合获取数据时添加过滤条件

Question

I'm trying to get data from edge collection based on a condition

In my edge collection, I have data like below

{
    _from: "rooms/1"
    _to: "users/1"
    type: "admin"
},{
    _from: "rooms/1"
    _to: "users/2"
    type: "member"
},{
    _from: "rooms/1"
    _to: "users/3"
    type: "member"
}

Now I want to get user info of admin only. I try with the below query but it is returning null values

FOR r IN rooms
    FILTER r._key == 1
    let admins = (
        FOR u IN ANY r rooms_users
            FILTER rooms_users.type == "admin"
        RETURN u
    )
RETURN MERGE([r, {admin: admins [0]}])

thanks in advance

Answer 1

I see three minor issues...

First, the _key attribute is always a string, so you need to quote the 1 in the first filter.

Second, in the "admins" subquery, you can't filter on "rooms_users" because that's the name of the edge collection, not the identification of the edge document(s). To filter on an attribute of an edge, you need to add a variable to the FOR statement to identify the edge ( e in this case) -docs .

Last, for performance reasons, I changed the graph query from ANY to INBOUND and gave it a limit of 1 . This means we will only find: (a) admins of THIS room, and won't traverse long directions up and down the graph trying to find any and all documents (it actually wound in a loop for me and timed out).

FOR r IN rooms
    FILTER r._key == '1'
    LET admins = (
        FOR u,e IN 1 INBOUND r rooms_users
            FILTER e.type == 'admin'
            RETURN u
    )
    RETURN MERGE([r, { admin: admins[0] }])