Added liking and security measures

features/posts/post_graph.js

@@ -0,0 +1,72 @@
+const driver = require("../../graph_db");
+const { graphIdToNumber } = require("../relations/friend_graph");
+
+const GRAPH = { database: process.env.GRAPH_DB_NAME };
+
+async function likePost(userId, postId) {
+  const { records } = await driver.executeQuery(
+    `MATCH (me:Person {db_id: $me})
+     MERGE (p:Post {db_id: $postId})
+     MERGE (me)-[l:LIKES]->(p)
+     SET l.created_at = coalesce(l.created_at, datetime())
+     RETURN me`,
+    { me: Number(userId), postId: Number(postId) },
+    GRAPH,
+  );
+  return records.length > 0;
+}
+
+async function unlikePost(userId, postId) {
+  await driver.executeQuery(
+    `MATCH (me:Person {db_id: $me})-[l:LIKES]->(p:Post {db_id: $postId})
+     DELETE l`,
+    { me: Number(userId), postId: Number(postId) },
+    GRAPH,
+  );
+}
+
+async function likeDataForPosts(userId, postIds) {
+  const ids = postIds.map(Number);
+  if (ids.length === 0) return new Map();
+  const { records } = await driver.executeQuery(
+    `MATCH (p:Post) WHERE p.db_id IN $ids
+     OPTIONAL MATCH (p)<-[l:LIKES]-(:Person)
+     WITH p, count(l) AS like_count
+     OPTIONAL MATCH (me:Person {db_id: $me})-[:LIKES]->(p)
+     RETURN p.db_id AS id, like_count, count(me) > 0 AS liked_by_me`,
+    { ids, me: Number(userId) },
+    GRAPH,
+  );
+  const result = new Map();
+  for (const record of records) {
+    result.set(graphIdToNumber(record.get("id")), {
+      like_count: Number(record.get("like_count")),
+      liked_by_me: Boolean(record.get("liked_by_me")),
+    });
+  }
+  return result;
+}
+
+async function deletePostNode(postId) {
+  await driver.executeQuery(
+    "MATCH (p:Post {db_id: $postId}) DETACH DELETE p",
+    { postId: Number(postId) },
+    GRAPH,
+  );
+}
+
+async function deletePostsByAuthor(authorId) {
+  await driver.executeQuery(
+    "MATCH (p:Post {author_id: $authorId}) DETACH DELETE p",
+    { authorId: Number(authorId) },
+    GRAPH,
+  );
+}
+
+module.exports = {
+  likePost,
+  unlikePost,
+  likeDataForPosts,
+  deletePostNode,
+  deletePostsByAuthor,
+};