For example, I have two collections with the following data:
Collection 1:
{
code: 1,
name: "data1"
},
{
code: 2,
name: "data2"
}
Collection 2:
{
code: 1,
type: "type1"
},
{
code: 1,
type: "type2"
},
{
code: 2,
type: "type2"
},
I want the output of the aggregation to be as follows:
{
code:1,
name: "data1",
types: ["type1","type2"]
},
{
code:2,
name:"data2",
types:["type2"]
}
localField
and foreignField
type
field from collection2db.col1.aggregate([
{
"$lookup": {
"from": "col2",
"localField": "code",
"foreignField": "code",
"as": "type"
}
},
{ $addFields: { type: "$type.type" } }
])
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