add Installation entity

packages/slackbot-proxy/src/entities/installation.ts

@@ -0,0 +1,21 @@
+import {
+  Property, Required,
+} from '@tsed/schema';
+import {
+  Column, Entity, PrimaryGeneratedColumn,
+} from 'typeorm';
+
+import { Installation as SlackInstallation } from '@slack/oauth';
+
+@Entity()
+export class Installation {
+
+  @PrimaryGeneratedColumn()
+  @Property()
+  id: number;
+
+  @Column({ type: 'json' })
+  @Required()
+  data: SlackInstallation;
+
+}

packages/slackbot-proxy/src/repositories/installation.ts

@@ -0,0 +1,14 @@
+import {
+  Repository, EntityRepository,
+} from 'typeorm';
+
+import { Installation } from '~/entities/installation';
+
+@EntityRepository(Installation)
+export class InstallationRepository extends Repository<Installation> {
+
+  findByID(id: string): Promise<Installation | undefined> {
+    return this.findOne(id);
+  }
+
+}