Social Media Schema

Complete MongoDB schemas for a social media app — Post, Like, Comment, Follow, and Notification.

Schemas for a social platform — posts with embedded likes for fast access, a separate Follow model for the social graph, and notifications.

Post Schema

// src/models/post.model.js
import mongoose from "mongoose";

const postSchema = new mongoose.Schema(
  {
    author: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "User",
      required: true,
    },
    content: {
      type: String,
      maxlength: 500,
    },
    images: [{ type: String }],
    // likes stored as an array of user ids — fast for small-medium scale
    likes: [{ type: mongoose.Schema.Types.ObjectId, ref: "User" }],
    commentsCount: {
      type: Number,
      default: 0,
    },
    sharesCount: {
      type: Number,
      default: 0,
    },
  },
  { timestamps: true }
);

const Post = mongoose.model("Post", postSchema);

export default Post;

Comment Schema

// src/models/comment.model.js
import mongoose from "mongoose";

const commentSchema = new mongoose.Schema(
  {
    post: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Post",
      required: true,
    },
    author: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "User",
      required: true,
    },
    content: {
      type: String,
      required: true,
      maxlength: 300,
    },
    likes: [{ type: mongoose.Schema.Types.ObjectId, ref: "User" }],
  },
  { timestamps: true }
);

const Comment = mongoose.model("Comment", commentSchema);

export default Comment;

Follow Schema

// src/models/follow.model.js
import mongoose from "mongoose";

const followSchema = new mongoose.Schema(
  {
    follower: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "User",
      required: true,
    },
    following: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "User",
      required: true,
    },
  },
  { timestamps: true }
);

// prevent following the same person twice
followSchema.index({ follower: 1, following: 1 }, { unique: true });

const Follow = mongoose.model("Follow", followSchema);

export default Follow;

Notification Schema

// src/models/notification.model.js
import mongoose from "mongoose";

const notificationSchema = new mongoose.Schema(
  {
    recipient: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "User",
      required: true,
    },
    sender: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "User",
      required: true,
    },
    type: {
      type: String,
      enum: ["like", "comment", "follow", "mention"],
      required: true,
    },
    post: {
      type: mongoose.Schema.Types.ObjectId,
      ref: "Post",
    },
    isRead: {
      type: Boolean,
      default: false,
    },
  },
  { timestamps: true }
);

const Notification = mongoose.model("Notification", notificationSchema);

export default Notification;

Common Usage Patterns

// toggle a like on a post
const post = await Post.findById(postId);
const alreadyLiked = post.likes.includes(userId);

if (alreadyLiked) {
  post.likes.pull(userId);
} else {
  post.likes.push(userId);

  // create a notification for the post author
  await Notification.create({
    recipient: post.author,
    sender: userId,
    type: "like",
    post: post._id,
  });
}

await post.save();

// follow a user
await Follow.create({ follower: currentUserId, following: targetUserId });

await Notification.create({
  recipient: targetUserId,
  sender: currentUserId,
  type: "follow",
});

// get a user's follower count and following count
const followerCount = await Follow.countDocuments({ following: userId });
const followingCount = await Follow.countDocuments({ follower: userId });

Storing likes as an embedded array on Post works well at small to medium scale. For apps with millions of likes per post, switch to a separate Like collection with post and user fields, similar to the Follow model — embedded arrays become slow to update at very large sizes.

Summary

Post.likes is an embedded array of user ids — simple and fast for typical app sizes
Follow is a separate collection with a compound unique index on follower + following — this is the standard pattern for social graphs, not an embedded array on User
Notification tracks type with an enum so the frontend can render different notification messages and icons
Use .pull() and .push() on Mongoose arrays to toggle likes without re-fetching the whole array manually
At very large scale, move likes from an embedded array to its own collection like Follow

Social Media Schema

Social Media Schema

Post Schema

Comment Schema

Follow Schema

Notification Schema

Common Usage Patterns

Summary

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