getcontestquestionbyid - mongo aggregation

Author: krishkumar84

cmd/portal-api/main.go

@@ -75,8 +75,7 @@ router.Handle("GET /api/admin/test",
 	router.HandleFunc("POST /api/testcase",testcase.CreateTestCase(storage))
 	router.HandleFunc("GET /api/contest",contest.GetAllContests(storage))
 	router.HandleFunc("GET /api/contest/{id}",contest.GetContestById(storage))
-    // router.HandleFunc("GET /api/users/{id}",users.GetById(storage))
-	// router.HandleFunc("GET /api/users",users.GetAll(storage))
+	router.HandleFunc("GET /api/question/{id}",question.GetQuestionById(storage))
 
 	//start server
 

pkg/http/handler/question/question.go

@@ -2,8 +2,9 @@ package question
 
 import (
 	"encoding/json"
+	"fmt"
 	"net/http"
-
+	"strings"
 	"github.com/krishkumar84/bdcoe-golang-portal/pkg/storage"
 	"github.com/krishkumar84/bdcoe-golang-portal/pkg/types"
 	"github.com/krishkumar84/bdcoe-golang-portal/pkg/utils/response"
@@ -25,4 +26,23 @@ func CreateQuestion(storage storage.Storage) http.HandlerFunc {
 
 		response.WriteJson(w, http.StatusCreated, map[string]string{"question_id": questionId})
 	}
+}
+
+func GetQuestionById(storage storage.Storage) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		path := r.URL.Path
+		id := path[strings.LastIndex(path, "/")+1:]
+		
+		if id == "" {
+			response.WriteJson(w, http.StatusBadRequest, response.GeneralError(fmt.Errorf("contest id is required")))
+			return
+		}
+		fmt.Println("Question ID: ", id)
+		question, err := storage.GetQuestionById(id)
+		if err != nil {
+			response.WriteJson(w, http.StatusInternalServerError, response.GeneralError(err))
+			return
+		}
+		response.WriteJson(w, http.StatusOK, question)
+	}
 }

pkg/storage/mongodb/mongodb.go

@@ -237,5 +237,74 @@ func (m *MongoDB) GetContestById(id string) ([]bson.M, error) {
         return nil, mongo.ErrNoDocuments
     }
 
+    return results, nil
+}
+
+func (m *MongoDB) GetQuestionById(id string) ([]bson.M, error) {
+    collection := m.db.Collection("questions")
+    ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+    defer cancel()
+
+    objectId, err := primitive.ObjectIDFromHex(id)
+    if err != nil {
+        return nil, fmt.Errorf("invalid question id format")
+    }
+
+    pipeline := mongo.Pipeline{
+        {{Key: "$match", Value: bson.D{{Key: "_id", Value: objectId}}}},
+        {{Key: "$addFields", Value: bson.D{
+            {Key: "test_case_ids", Value: bson.D{
+                {Key: "$map", Value: bson.D{
+                    {Key: "input", Value: "$test_case_ids"},
+                    {Key: "as", Value: "tid"},
+                    {Key: "in", Value: bson.D{
+                        {Key: "$toObjectId", Value: "$$tid"},
+                    }},
+                }},
+            }},
+        }}},
+        {{Key: "$lookup", Value: bson.D{
+            {Key: "from", Value: "test_cases"},
+            {Key: "localField", Value: "test_case_ids"},
+            {Key: "foreignField", Value: "_id"},
+            {Key: "as", Value: "test_cases"},
+        }}},
+        {{Key: "$project", Value: bson.D{
+            {Key: "_id", Value: 1},
+            {Key: "title", Value: 1},
+            {Key: "description", Value: 1},
+            {Key: "difficulty", Value: 1},
+            {Key: "tags", Value: 1},
+            {Key: "points", Value: 1},
+            {Key: "test_cases", Value: bson.D{
+                {Key: "$map", Value: bson.D{
+                    {Key: "input", Value: "$test_cases"},
+                    {Key: "as", Value: "tc"},
+                    {Key: "in", Value: bson.D{
+                        {Key: "_id", Value: "$$tc._id"},
+                        {Key: "input", Value: "$$tc.input"},
+                        {Key: "expected_output", Value: "$$tc.expected_output"},
+                        {Key: "visibility", Value: "$$tc.visibility"},
+                    }},
+                }},
+            }},
+        }}},
+    }
+
+    var results []bson.M
+    cursor, err := collection.Aggregate(ctx, pipeline)
+    if err != nil {
+        return nil, fmt.Errorf("error executing aggregation: %v", err)
+    }
+    defer cursor.Close(ctx)
+
+    if err := cursor.All(ctx, &results); err != nil {
+        return nil, fmt.Errorf("error decoding result: %v", err)
+    }
+
+    if len(results) == 0 {
+        return nil, mongo.ErrNoDocuments
+    }
+
     return results, nil
 }

pkg/storage/storage.go

@@ -16,4 +16,5 @@ type Storage interface {
 	CreateTestCase(testCase types.TestCase) (string, error)
 	GetAllContests() ([]types.ContestBasicInfo, error)
 	GetContestById(id string) ([]bson.M, error)
+	GetQuestionById(id string) ([]bson.M, error)
 }

pkg/types/models.go

@@ -33,7 +33,7 @@ type Contest struct {
 }
 
 type Question struct {
-    ID        string    `bson:"_id,omitempty" json:"question_id" validate:"required"`
+    ID        string    `bson:"_id,omitempty" json:"question_id"`
     Title     string    `bson:"title" json:"title" validate:"required"`
     Description string `bson:"description" json:"description" validate:"required"`
     Difficulty string `bson:"difficulty" json:"difficulty"`