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Type:
Question
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Resolution: Done
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Priority:
Major - P3
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None
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Affects Version/s: None
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Component/s: Aggregation Framework
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None
Here is the example
hdbrs:PRIMARY> db.models.find()
{ "_id" : ObjectId("5f6c72cec48056980f22d3d0"), "id" : "a1", "refs" : [ { "id" : "b1" }, { "id" : "c1" }, { "id" : "d1" }, { "id" : "e1" } ] }
{ "_id" : ObjectId("5f6c72e3c48056980f22d3d1"), "id" : "c1", "refs" : [ { "id" : "c11" }, { "id" : "c1" }, { "id" : "d1" }, { "id" : "c12" }, { "id" : "c13" } ] }
{ "_id" : ObjectId("5f6c72f2c48056980f22d3d2"), "id" : "b1", "refs" : [ { "id" : "b11" }, { "id" : "b12" }, { "id" : "b13" } ] }
{ "_id" : ObjectId("5f6c72ffc48056980f22d3d3"), "id" : "d1", "refs" : [ { "id" : "d11" }, { "id" : "d12" }, { "id" : "d13" } ] }
{ "_id" : ObjectId("5f6c78d7c48056980f22d3d4"), "id" : "c11", "refs" : [ { "id" : "c21" }, { "id" : "c22" } ] }
In the above example, when we search for the "c12" and "d13" id and all of it's parents using aggregation.
hdbrs:PRIMARY> db.models.aggregate([{$match: {"refs.id": {$in: searchIds}}}, {$graphLookup: {from: "models", startWith: searchIds, connectFromField: "id", connectToField: "refs.id", as: "Tree", maxDepth: 2, depthField: "depth" }}, {$project: {"Tree.id": 1, "Tree.depth": 1, _id: 0}}], {explain: false})
// Results
{ "Tree" : [ { "id" : "c1", "depth" : NumberLong(1) }, { "id" : "a1", "depth" : NumberLong(1) }, { "id" : "c11", "depth" : NumberLong(0) }, { "id" : "d1", "depth" : NumberLong(0) } ] }
{ "Tree" : [ { "id" : "a1", "depth" : NumberLong(1) }, { "id" : "c1", "depth" : NumberLong(1) }, { "id" : "d1", "depth" : NumberLong(0) }, { "id" : "c11", "depth" : NumberLong(0) } ] }
As per the results you can see both documents contain the same document ids. If we allow dynamic search on the value "Tree.id" where the condition
{restrictSearchWithMatch: {$nin: "Tree.id"}}
will stop the repeated documents from getting again into the results set and instead of the different documents from the result set can we get output something like a single document as result set.