Refactor professor course and section pipelines into a pipeline builder function

api/controllers/professor.go

@@ -197,6 +197,82 @@ func ProfessorCourseById() gin.HandlerFunc {
 	}
 }
 
+// Pipeline builder for professor aggregate endpoints
+func professorPipeline(endpoint string, professorQuery bson.M, paginateMap map[string]int64) mongo.Pipeline {
+	// common stages
+	baseStages := mongo.Pipeline{
+		// filter the professors
+		bson.D{{Key: "$match", Value: professorQuery}},
+
+		// paginate the professors before pulling the courses from those professor
+		bson.D{{Key: "$skip", Value: paginateMap["former_offset"]}}, // skip to the specified offset
+		bson.D{{Key: "$limit", Value: paginateMap["limit"]}},        // limit to the specified number of professors
+
+		// lookup the array of sections from sections collection
+		bson.D{{Key: "$lookup", Value: bson.D{
+			{Key: "from", Value: "sections"},
+			{Key: "localField", Value: "sections"},
+			{Key: "foreignField", Value: "_id"},
+			{Key: "as", Value: "sections"},
+		}}},
+
+		// keep order deterministic between calls
+		bson.D{{Key: "$sort", Value: bson.D{{Key: "_id", Value: 1}}}},
+	}
+
+	// course pagination stages
+	paginationStages := mongo.Pipeline{
+		bson.D{{Key: "$skip", Value: paginateMap["latter_offset"]}},
+		bson.D{{Key: "$limit", Value: paginateMap["limit"]}},
+	}
+
+	if endpoint == "courses" {
+		courseStages := mongo.Pipeline{
+			// project the courses referenced by each section in the array
+			bson.D{{Key: "$project", Value: bson.D{{Key: "courses", Value: "$sections.course_reference"}}}},
+
+			// lookup the array of courses from coures collection
+			bson.D{{Key: "$lookup", Value: bson.D{
+				{Key: "from", Value: "courses"},
+				{Key: "localField", Value: "courses"},
+				{Key: "foreignField", Value: "_id"},
+				{Key: "as", Value: "courses"},
+			}}},
+
+			// unwind the courses
+			bson.D{{Key: "$unwind", Value: bson.D{
+				{Key: "path", Value: "$courses"},
+				{Key: "preserveNullAndEmptyArrays", Value: false}, // to avoid the professor documents that can't be replaced
+			}}},
+
+			// replace the combination of ids and courses with the courses entirely
+			bson.D{{Key: "$replaceWith", Value: "$courses"}},
+		}
+
+		return append(append(baseStages, courseStages...), paginationStages...)
+	}
+
+	if endpoint == "sections" {
+		sectionStages := mongo.Pipeline{
+			// project the sections
+			bson.D{{Key: "$project", Value: bson.D{{Key: "sections", Value: "$sections"}}}},
+
+			// unwind the sections
+			bson.D{{Key: "$unwind", Value: bson.D{
+				{Key: "path", Value: "$sections"},
+				{Key: "preserveNullAndEmptyArrays", Value: false}, // to avoid the professor documents that can't be replaced
+			}}},
+
+			// replace the combination of ids and sections with the sections entirely
+			bson.D{{Key: "$replaceWith", Value: "$sections"}},
+		}
+
+		return append(append(baseStages, sectionStages...), paginationStages...)
+	}
+
+	return append(baseStages, paginationStages...) // fallback (shouldn't happen because we call with either courses or sections)
+}
+
 // Get all of the courses of the professors depending on the type of flag
 func professorCourse(flag string, c *gin.Context) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
@@ -221,49 +297,7 @@ func professorCourse(flag string, c *gin.Context) {
 	}
 
 	// Pipeline to query the courses from the filtered professors (or a single professor)
-	professorCoursePipeline := mongo.Pipeline{
-		// filter the professors
-		bson.D{{Key: "$match", Value: professorQuery}},
-
-		// paginate the professors before pulling the courses from those professor
-		bson.D{{Key: "$skip", Value: paginateMap["former_offset"]}}, // skip to the specified offset
-		bson.D{{Key: "$limit", Value: paginateMap["limit"]}},        // limit to the specified number of professors
-
-		// lookup the array of sections from sections collection
-		bson.D{{Key: "$lookup", Value: bson.D{
-			{Key: "from", Value: "sections"},
-			{Key: "localField", Value: "sections"},
-			{Key: "foreignField", Value: "_id"},
-			{Key: "as", Value: "sections"},
-		}}},
-
-		// project the courses referenced by each section in the array
-		bson.D{{Key: "$project", Value: bson.D{{Key: "courses", Value: "$sections.course_reference"}}}},
-
-		// lookup the array of courses from coures collection
-		bson.D{{Key: "$lookup", Value: bson.D{
-			{Key: "from", Value: "courses"},
-			{Key: "localField", Value: "courses"},
-			{Key: "foreignField", Value: "_id"},
-			{Key: "as", Value: "courses"},
-		}}},
-
-		// unwind the courses
-		bson.D{{Key: "$unwind", Value: bson.D{
-			{Key: "path", Value: "$courses"},
-			{Key: "preserveNullAndEmptyArrays", Value: false}, // to avoid the professor documents that can't be replaced
-		}}},
-
-		// replace the combination of ids and courses with the courses entirely
-		bson.D{{Key: "$replaceWith", Value: "$courses"}},
-
-		// keep order deterministic between calls
-		bson.D{{Key: "$sort", Value: bson.D{{Key: "_id", Value: 1}}}},
-
-		// paginate the courses
-		bson.D{{Key: "$skip", Value: paginateMap["latter_offset"]}},
-		bson.D{{Key: "$limit", Value: paginateMap["limit"]}},
-	}
+	professorCoursePipeline := professorPipeline("courses", professorQuery, paginateMap)
 
 	// Perform aggreration on the pipeline
 	cursor, err := professorCollection.Aggregate(ctx, professorCoursePipeline)
@@ -353,41 +387,7 @@ func professorSection(flag string, c *gin.Context) {
 	}
 
 	// Pipeline to query the courses from the filtered professors (or a single professor)
-	professorSectionPipeline := mongo.Pipeline{
-		// filter the professors
-		bson.D{{Key: "$match", Value: professorQuery}},
-
-		// paginate the professors before pulling the courses from those professor
-		bson.D{{Key: "$skip", Value: paginateMap["former_offset"]}}, // skip to the specified offset
-		bson.D{{Key: "$limit", Value: paginateMap["limit"]}},        // limit to the specified number of professors
-
-		// lookup the array of sections from sections collection
-		bson.D{{Key: "$lookup", Value: bson.D{
-			{Key: "from", Value: "sections"},
-			{Key: "localField", Value: "sections"},
-			{Key: "foreignField", Value: "_id"},
-			{Key: "as", Value: "sections"},
-		}}},
-
-		// project the sections
-		bson.D{{Key: "$project", Value: bson.D{{Key: "sections", Value: "$sections"}}}},
-
-		// unwind the sections
-		bson.D{{Key: "$unwind", Value: bson.D{
-			{Key: "path", Value: "$sections"},
-			{Key: "preserveNullAndEmptyArrays", Value: false}, // to avoid the professor documents that can't be replaced
-		}}},
-
-		// replace the combination of ids and sections with the sections entirely
-		bson.D{{Key: "$replaceWith", Value: "$sections"}},
-
-		// keep order deterministic between calls
-		bson.D{{Key: "$sort", Value: bson.D{{Key: "_id", Value: 1}}}},
-
-		// paginate the sections
-		bson.D{{Key: "$skip", Value: paginateMap["latter_offset"]}},
-		bson.D{{Key: "$limit", Value: paginateMap["limit"]}},
-	}
+	professorSectionPipeline := professorPipeline("sections", professorQuery, paginateMap)
 
 	// Perform aggreration on the pipeline
 	cursor, err := professorCollection.Aggregate(ctx, professorSectionPipeline)

api/controllers/section.go

@@ -122,8 +122,8 @@ func SectionById(c *gin.Context) {
 // @Tags			Sections
 // @Description	"Returns paginated list of courses of all the sections matching the query's string-typed key-value pairs. See former_offset and latter_offset for pagination details."
 // @Produce		json
-// @Param			former_offset					query		number								false	"The starting position of the current page of sections (e.g. For starting at the 16th section, former_offset=16)."
-// @Param			latter_offset					query		number								false	"The starting position of the current page of courses (e.g. For starting at the 16th course, latter_offset=16)."
+// @Param			former_offset					query		number								false	"The starting position of the current page of professors (e.g. For starting at the 17th professor, former_offset=16)."
+// @Param			latter_offset					query		number								false	"The starting position of the current page of sections (e.g. For starting at the 17th professor, offset=16)."
 // @Param			section_number					query		string								false	"The section's official number"
 // @Param			academic_session.name			query		string								false	"The name of the academic session of the section"
 // @Param			academic_session.start_date		query		string								false	"The date of classes starting for the section"

api/go.mod

@@ -13,7 +13,7 @@ require (
 	github.com/swaggo/files v1.0.1
 	github.com/swaggo/gin-swagger v1.6.1
 	github.com/swaggo/swag v1.16.6
-	go.mongodb.org/mongo-driver v1.17.3
+	go.mongodb.org/mongo-driver v1.17.4
 	google.golang.org/api v0.224.0
 )
 

api/go.sum

@@ -200,6 +200,8 @@ github.com/youmark/pkcs8 v0.0.0-20240726163527-a2c0da244d78/go.mod h1:aL8wCCfTfS
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 go.mongodb.org/mongo-driver v1.17.3 h1:TQyXhnsWfWtgAhMtOgtYHMTkZIfBTpMTsMnd9ZBeHxQ=
 go.mongodb.org/mongo-driver v1.17.3/go.mod h1:Hy04i7O2kC4RS06ZrhPRqj/u4DTYkFDAAccj+rVKqgQ=
+go.mongodb.org/mongo-driver v1.17.4 h1:jUorfmVzljjr0FLzYQsGP8cgN/qzzxlY9Vh0C9KFXVw=
+go.mongodb.org/mongo-driver v1.17.4/go.mod h1:Hy04i7O2kC4RS06ZrhPRqj/u4DTYkFDAAccj+rVKqgQ=
 go.opentelemetry.io/auto/sdk v1.1.0 h1:cH53jehLUN6UFLY71z+NDOiNJqDdPRaXzTel0sJySYA=
 go.opentelemetry.io/auto/sdk v1.1.0/go.mod h1:3wSPjt5PWp2RhlCcmmOial7AvC4DQqZb7a7wCow3W8A=
 go.opentelemetry.io/contrib/detectors/gcp v1.34.0 h1:JRxssobiPg23otYU5SbWtQC//snGVIM3Tx6QRzlQBao=