Details
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Improvement
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Status: Backlog
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Major - P3
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Resolution: Unresolved
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None
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None
Description
Schema
x:\{type: String, required: true},
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a: [{
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_b: \{type: Schema.Types.ObjectId, ref: "B", required: true},
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c: \{type: Number, required: true},
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_d: \{type: Schema.Types.ObjectId, ref: "D", required: true},
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e: {
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f: \{type: Number, required: true}
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}
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}]
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Lookup Stage
{
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"$lookup": {
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from: "B",
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localField: "a._b",
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foreignField: "_id",
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as: "a._b"
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}
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}
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Expected Output
{
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x:/.../,
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a:[{
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_b:[Object],
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c:/.../,
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_d:/.../,
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e:{
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f:/.../
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}
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}]
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}
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Output
{
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x:/.../,
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a: {
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_b: [Object]
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}
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}
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As you can see above, fields inside the "a" gets overwritten by the $lookup operation, and the field called "a" turns into an object after the aggregation (just like in the behavior of the $unwind operator).
Attachments
Issue Links
- is duplicated by
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SERVER-42307 $lookup overwrites the entire object and erases fields (other than what "as" holds) when used inside an array of nested objects
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- Closed
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- related to
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- Closed
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