createComment deleteComment likePost

graphql/resolvers/comments.js

+const Post = require("../../models/Post");
+const checkAuth = require("../../util/check-auth");
+const { AuthenticationError, UserInputError } = require("apollo-server");
+
+module.exports = {
+  Mutation: {
+    createComment: async (_, { postId, body }, context) => {
+      const { username } = checkAuth(context);
+
+      if (body.trim() === "") {
+        throw new UserInputError("Empty comment", {
+          errors: {
+            body: "Comment body must not empty"
+          }
+        });
+      }
+
+      const post = await Post.findById(postId);
+
+      if (post) {
+        post.comments.unshift({
+          body,
+          username,
+          createdAt: new Date().toISOString()
+        });
+
+        await post.save();
+        return post;
+      } else throw new UserInputError("Post not found");
+    },
+    deleteComment: async (_, { postId, commentId }, context) => {
+      const { username } = checkAuth(context);
+
+      const post = await Post.findById(postId);
+
+      if (post) {
+        const commentIndex = post.comments.findIndex(c => c.id === commentId);
+
+        if (post.comments[commentIndex].username === username) {
+          post.comments.splice(commentIndex, 1);
+          await post.save();
+          return post;
+        } else {
+          throw new AuthenticationError("Action not allowed");
+        }
+      } else {
+        throw new UserInputError("Post not found");
+      }
+    }
+  }
+};

graphql/resolvers/index.js

 const postsResolvers = require("./posts");
 const usersResolvers = require("./users");
+const commentsResolvers = require("./comments");
 
 module.exports = {
   Query: {
@@ -7,6 +8,7 @@ module.exports = {
   },
   Mutation: {
     ...usersResolvers.Mutation,
-    ...postsResolvers.Mutation
+    ...postsResolvers.Mutation,
+    ...commentsResolvers.Mutation
   }
 };

graphql/resolvers/posts.js

 const Post = require("../../models/Post");
 const checkAuth = require("../../util/check-auth");
-const { AuthenticationError } = require("apollo-server");
+const { AuthenticationError, UserInputError } = require("apollo-server");
 
 module.exports = {
   Query: {
@@ -55,6 +55,27 @@ module.exports = {
       } catch (err) {
         throw new Error(err);
       }
+    },
+    async likePost(_, { postId }, context) {
+      const { username } = checkAuth(context);
+
+      const post = await Post.findById(postId);
+
+      if (post) {
+        if (post.likes.find(like => like.username === username)) {
+          post.likes = post.likes.filter(like => like.username !== username);
+        } else {
+          post.likes.push({
+            username,
+            createdAt: new Date().toISOString()
+          });
+        }
+
+        await post.save();
+        return post;
+      } else {
+        throw new UserInputError("Post not found");
+      }
     }
   }
 };

graphql/typeDefs.js

@@ -6,6 +6,21 @@ module.exports = gql`
     body: String!
     createdAt: String!
     username: String!
+    comments: [Comment]!
+    likes: [Like]!
+  }
+
+  type Comment {
+    id: ID!
+    body: String!
+    username: String!
+    createdAt: String!
+  }
+
+  type Like {
+    id: ID!
+    username: String!
+    createdAt: String!
   }
 
   type Query {
@@ -33,5 +48,8 @@ module.exports = gql`
     login(username: String!, password: String!): User!
     createPost(body: String!): Post!
     deletePost(postId: ID!): String!
+    createComment(postId: ID!, body: String!): Post!
+    deleteComment(postId: ID!, commentId: ID!): Post!
+    likePost(postId: ID!): Post!
   }
 `;