feat: add course rating and review endpoint

BackendAcademy/src/courses/course-rating.entity.ts

@@ -0,0 +1,56 @@
+import {
+  Column,
+  CreateDateColumn,
+  Entity,
+  Index,
+  PrimaryGeneratedColumn,
+  UpdateDateColumn,
+} from 'typeorm';
+
+/**
+ * A learner's rating and optional review for a course.
+ *
+ * Each user can rate a course at most once; submitting a new rating
+ * will update the existing one (upsert semantics).
+ */
+@Entity({ name: 'course_ratings' })
+@Index(['courseId', 'userId'], { unique: true })
+export class CourseRatingEntity {
+  @PrimaryGeneratedColumn('increment')
+  id: number;
+
+  @Index('idx_course_ratings_course_id')
+  @Column({ name: 'course_id', type: 'uuid' })
+  courseId: string;
+
+  @Index('idx_course_ratings_user_id')
+  @Column({ name: 'user_id', type: 'uuid' })
+  userId: string;
+
+  /**
+   * Rating value from 1 to 5 (inclusive).
+   * Stored as SMALLINT with a CHECK constraint in the migration.
+   */
+  @Column({ type: 'smallint' })
+  rating: number;
+
+  /**
+   * Optional text review from the learner.
+   * Max 2000 characters.
+   */
+  @Column({ type: 'text', nullable: true })
+  review: string | null;
+
+  @CreateDateColumn({ name: 'created_at', type: 'timestamptz' })
+  createdAt: Date;
+
+  @UpdateDateColumn({ name: 'updated_at', type: 'timestamptz' })
+  updatedAt: Date;
+
+  constructor(partial: Partial<CourseRatingEntity> = {}) {
+    Object.assign(this, partial);
+    this.createdAt = this.createdAt || new Date();
+    this.updatedAt = this.updatedAt || new Date();
+    this.review = this.review || null;
+  }
+}