Added Datastore Generic

backend-services/friend-service/src/Datastores/DataStore.ts

+import mongoose, { Model, Schema } from 'mongoose'
+
+/**
+ * Defines common datastore functionality
+ */
+export abstract class DataStore<T> {
+
+  /**
+   * Mongoose model pertaining to the datastore type
+   */
+   public Model: Model<any>
+
+   constructor (modelName: string, schema: Schema) {
+     this.Model = mongoose.model(modelName, schema)
+   }
+
+   /**
+   * Finds a single item matching a given query
+   * @param query
+   * @returns
+   */
+    public GetItem = async (query: any): Promise<T | null> => {
+      return await this.Model.findOne(query)
+    }
+}
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