数据库：将activities等表移到gm数据库中

shared/db/Activity.ts

@@ -1,5 +1,5 @@
 import BaseModel from './BaseModel';
-import { index, getModelForClass, prop, DocumentType } from '@typegoose/typegoose';
+import { index, getModelForClass, prop, DocumentType, ReturnModelType, mongoose } from '@typegoose/typegoose';
 import { CounterModel } from './Counter';
 import { COUNTER } from '../consts';
 import { ActivityGroupModel } from './ActivityGroup';
@@ -183,7 +183,13 @@ export default class Activity extends BaseModel {
     }
 }
 
-export const ActivityModel = getModelForClass(Activity);
+
+export let ActivityModel: ReturnModelType<typeof Activity, {}>;
+export function loadActivity(connect: mongoose.Connection) {
+    ActivityModel = getModelForClass(Activity, {
+        existingConnection: connect
+    });
+}
 
 export interface ActivityModelType extends Pick<DocumentType<Activity>, keyof Activity> { }
 export type ActivityModelTypeParam = Partial<ActivityModelType>; // 将所有字段变成可选项