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Type:
Bug
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Resolution: Works as Designed
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Priority:
Unknown
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None
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Affects Version/s: None
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Component/s: None
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Dotnet Drivers
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Summary
MongoDB.Driver version: 2.23.1
Server version 7.0.8
I need to build a projection using $filter. The closest thing that I could find in the C# driver is projection.ElemMatch() method. This generates a Mongo query using $elemMatch and it fails at run time.
How to Reproduce
This is the handwritten Mongo query that I want to build in C#:
{
"$project": {
"session_id": 1,
"is_priority": 1,
"document_created_on": 1,
"document_created_by": 1,
"reviews": {
"$filter": {
"input": "$reviews",
"as": "reviews",
"cond": {
"$and": [{
"$eq": ["$$reviews.type", "MBRVW"]
}, {
"$or": [{
"$eq": ["$$reviews.status_code", "APPROVED"]
}, {
"$eq": ["$$reviews.status_code", "CONTESTED"]
}
]
}
]
}
}
}
}
}
This is the C# code:
public static ProjectionDefinition<ProviderFeedback> CreateProjection2(FeedbackGetRequestDto request) { List<string> statusFilters = GetStatusFilters(request); var projection = Builders<ProviderFeedback>.Projection .Include(f => f.SessionId) .Include(f => f.IsPriority) .Include(f => f.DocumentCreatedOn) .Include(f => f.DocumentCreatedBy); Expression<Func<Review, bool>> filter = review => review.TypeCode == request.ReviewType && statusFilters.Contains(review.StatusCode) : projection = projection.ElemMatch(f => f.Reviews, filter); return projection; }
And this is the Mogo query that it generates:
{
"$project": {
"session_id": 1,
"is_priority": 1,
"document_created_on": 1,
"document_created_by": 1,
"reviews": {
"$elemMatch": {
"type": "MBRVW",
"status_code": {
"$in": ["APPROVED", "CONTESTED"]
}
}
}
}
}
This is the runtime error:
MongoDB.Driver.MongoCommandException: Command aggregate failed: Invalid $project :: caused by :: Cannot use $elemMatch in this context.
at MongoDB.Driver.Core.WireProtocol.CommandUsingCommandMessageWireProtocol.ProcessResponse(ConnectionId connectionId, CommandMessage responseMessage)
Please let me know what C# code should I use so that it generates a proper Mongo query.