如何在 ArangoDB 中将两个返回变量的 output 合并为一个？

Question

Beginner with ArangoDB here:

I have two outputs stored in two variables, say: a and b .
The structure of the items in variable a and b are exactly the same, but with different data. Example as follows:

a = {
    "user": "Thor Odinson",
    "city": "New York",
    "action": "Lives"
}

b = {
    "user": "Thor Odinson",
    "city": "New York",
    "action": "Childhood"
}

How would I combine the output from the two variables into one as follows?

{
    "user": "Thor Odinson",
    "city": "New York",
    "action": ["Lives", "Childhood"]
}

Ideally, combine the two documents with user and city as common denominator, and action merged into an array? Not sure if Arango has a function like that natively, but any help towards the right direction would be a great help too!
I am open to writing the logic in my code instead, but I'd like to avoid that as much as possible.

I've been playing around with COLLECT , UNION , and MERGE but with no luck.

Answer 1

Defining data as

LET a = {
    "user": "Thor Odinson",
    "city": "New York",
    "action": "Lives"
}

LET b = {
    "user": "Thor Odinson",
    "city": "New York",
    "action": "Childhood"
}

LET data = [a,b]

To get the desired result for data , this should get you started:

FOR i IN data
    COLLECT user = i.user, city = i.city INTO groups = i.action 
    RETURN {"user": user, "city": city, "action": groups}

That gives the desired result:

[
  {
    "user": "Thor Odinson",
    "city": "New York",
    "action": [
      "Lives",
      "Childhood"
    ]
  }
]

If you need more control over the variables returned, use KEEP :

FOR i IN data
    LET action = i.action
    COLLECT user = i.user, city = i.city INTO groups KEEP action
    RETURN {"user": user, "city": city, "action": groups[*].action}