Query builder index usage optimisations

Sources/FluentMongo/Document+Nested.swift

@@ -57,3 +57,40 @@ public extension Document {
         }
     }
 }
+
+extension Document {
+
+    func byRemovingKeysPrefix(_ prefix: String) -> Document {
+
+        func removeKeysPrefix(_ document: Document) -> Document {
+
+            func ensureNoRootNameSpace(_ value: String) -> String {
+                let components = value.components(separatedBy: ".")
+                if components.first == prefix {
+                    return components.dropFirst().joined(separator: ".")
+                } else {
+                    return value
+                }
+            }
+
+            var mutableFilter = Document()
+
+            for item in document {
+                switch document[item.key] {
+                case .some(let value as Document):
+                    mutableFilter[ensureNoRootNameSpace(item.key)] = removeKeysPrefix(value)
+                case .some(let value as [Document]):
+                    mutableFilter[ensureNoRootNameSpace(item.key)] = value.map { removeKeysPrefix($0) }
+                case .some(let value):
+                    mutableFilter[ensureNoRootNameSpace(item.key)] = value
+                case .none:
+                    mutableFilter[ensureNoRootNameSpace(item.key)] = nil
+                }
+            }
+
+            return mutableFilter
+        }
+
+        return removeKeysPrefix(self)
+    }
+}

Sources/FluentMongo/FluentMongoQuery.swift

@@ -67,14 +67,14 @@ public struct FluentMongoQuery {
                 continue
             }
 
-            projection[field.pathWithNamespace.joined(separator: ".")] = true
+            projection[(field.entity == self.collection ? field.path : field.pathWithNamespace).joined(separator: ".")] = true
         }
 
         guard !projection.isEmpty else {
             return nil
         }
 
-        projection[self.collection + "._id"] = true
+        projection["_id"] = true
 
         return projection
     }
@@ -88,18 +88,19 @@ public struct FluentMongoQuery {
                 continue
             }
             // It is not possible to use dots when specifying an id field for $group
-            id[field.pathWithNamespace.joined(separator: ":")] = "$" + field.pathWithNamespace.joined(separator: ".")
+            let path = (field.entity == self.collection ? field.path : field.pathWithNamespace)
+            id[field.pathWithNamespace.joined(separator: ":")] = "$" + path.joined(separator: ".")
         }
 
         if id.isEmpty {
-            id[self.collection + ":_id"] = "$" + self.collection + "._id"
+            id[self.collection + ":_id"] = "$_id"
         }
 
         group["_id"] = id
-        group["doc"] = ["$first": "$" + self.collection] as Document
+        group["doc"] = ["$first": "$$ROOT"] as Document
 
         stages.append(["$group": group])
-        stages.append(["$project": [self.collection: "$doc"] as Document])
+        stages.append(["$replaceRoot": ["newRoot": "$doc"] as Document])
 
         return stages
     }
@@ -122,7 +123,8 @@ public struct FluentMongoQuery {
                         continue
                     }
                     // It seems that fluent only support one aggregated field
-                    group[FluentMongoQuery.defaultAggregateField] = [accumulator.value: "$" + field.pathWithNamespace.joined(separator: ".")] as Document
+                    let path = (field.entity == self.collection ? field.path : field.pathWithNamespace).joined(separator: ".")
+                    group[FluentMongoQuery.defaultAggregateField] = [accumulator.value: "$" + path] as Document
                     break
                 }
 
@@ -136,9 +138,6 @@ public struct FluentMongoQuery {
     func aggregationPipeline() -> [Document] {
         var pipeline = [Document]()
 
-        // Namespace root document
-        pipeline.append(["$project": [self.collection: "$$ROOT"] as Document])
-
         // Joins
         if !self.joins.isEmpty {
             pipeline.append(contentsOf: self.joins)
@@ -177,9 +176,18 @@ public struct FluentMongoQuery {
         // Aggregates
         if let aggregates = self.aggregates() {
             pipeline.append(contentsOf: aggregates)
-        } else {
-            // Remove namespace
-            pipeline.append(["$replaceRoot": ["newRoot": "$" + self.collection] as Document])
+        }
+
+        // Remove joined collections from the output
+        if !self.joins.isEmpty {
+            var projection = Document()
+            for join in self.joins {
+                guard let field = join["$lookup", "as"] as? String else {
+                    continue
+                }
+                projection[field] = false
+            }
+            pipeline.append(["$project": projection])
         }
 
         return pipeline

Sources/FluentMongo/FluentMongoQueryFilter.swift

@@ -50,11 +50,14 @@ extension Database where Self: QuerySupporting, Self.Query == FluentMongoQuery,
     }
 
     public static func queryFilterApply(_ filter: QueryFilter, to query: inout Query) {
+
+        let filterByRemovingRootNamespace = filter.byRemovingKeysPrefix(query.collection)
+
         switch query.filter {
         case .some(let document):
-            query.filter = [query.defaultFilterRelation.rawValue: [document, filter]]
+            query.filter = [query.defaultFilterRelation.rawValue: [document, filterByRemovingRootNamespace]]
         case .none:
-            query.filter = filter
+            query.filter = filterByRemovingRootNamespace
         }
     }
 }

Sources/FluentMongo/FluentMongoQueryJoin.swift

@@ -34,7 +34,7 @@ extension Database where Self: JoinSupporting, Self.QueryJoin == FluentMongoQuer
         let lookup: Document = [
             "$lookup": [
                 "from": collection,
-                "localField": base.pathWithNamespace.joined(separator: "."),
+                "localField": base.path.joined(separator: "."),
                 "foreignField": joined.path.joined(separator: "."),
                 "as": collection
             ] as Document

Sources/FluentMongo/FluentMongoQuerySort.swift

@@ -36,7 +36,7 @@ extension Database where Self: QuerySupporting, Self.Query == FluentMongoQuery,
         for field in sort {
             document[field.key] = field.value
         }
-        query.sort = document
+        query.sort = document.byRemovingKeysPrefix(query.collection)
     }
 }