simple message create mutation and query

backend/src/schema/resolvers/message.ts

@@ -0,0 +1,50 @@
+import { v4 as uuid } from 'uuid'
+import { neo4jgraphql } from 'neo4j-graphql-js'
+
+export default {
+  Query: {
+    Message:  async (object, params, context, resolveInfo) => {
+      if (!params.filter) params.filter = {}
+      params.filter.room = {
+        users_some: {
+          id: context.user.id,
+        },
+      }
+      return neo4jgraphql(object, params, context, resolveInfo)
+    },
+  },
+  Mutation: {
+    CreateMessage: async (_parent, params, context, _resolveInfo) => {
+      const { roomId, content } = params
+      const { user: { id: currentUserId } } = context
+      const messageId = uuid()
+      const session = context.driver.session()
+      const writeTxResultPromise = session.writeTransaction(async (transaction) => {
+        const createMessageCypher = `
+          MATCH (currentUser:User { id: $currentUserId })-[:CHATS_IN]->(room:Room { id: $roomId })
+          MERGE (currentUser)-[:CREATED]->(message:Message)-[:INSIDE]->(room)
+          SET message.createdAt = toString(datetime()),
+          message.id = $messageId
+          message.content = $content
+          RETURN message { .* }
+        `
+        const createMessageTxResponse = await transaction.run(
+          createMessageCypher,
+          { currentUserId, roomId, messageId, content }
+        )
+        const [message] = await createMessageTxResponse.records.map((record) =>
+                                                                    record.get('message'),
+                                                                   )
+        return message
+      })
+      try {
+        const message = await writeTxResultPromise
+        return message
+      } catch (error) {
+        throw new Error(error)
+      } finally {
+        session.close()
+      } 
+    },
+  },
+}

backend/src/schema/types/type/Message.gql

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+input _MessageFilter {
+  room: _RoomFilter
+}
+
+type Message {
+  id: ID!
+  createdAt: String
+  updatedAt: String
+
+  content: String!
+  
+  author: User! @relation(name: "CREATED", direction: "IN")
+  room: Room! @relation(name: "INSIDE", direction: "OUT")
+}
+
+type Mutation {
+  CreateMessage(
+    roomId: ID!
+    content: String!
+  ): Message
+}
+
+type Query {
+  Message(roomId: ID!): [Message]
+}