Introduces flow types for storage (#4349)

* Introduces flow types for storage

* Better typing of QueryOptions

* Adds flow types to SchemaCOntroller,

- runs flow on pre tests
- fixes flow

* Adds ClassLevelPermissions type

* Moves Controller types into a single file

* Changes import styles

* Changes import styles

* fixing method setIndexesWithSchemaFormat (#4454)

Fixing invalid database code in method `setIndexesWithSchemaFormat`:

* It must be a transaction, not a task, as it executes multiple database changes
* It should contain the initial queries inside the transaction, providing the context, not outside it;
* Replaced the code with the ES6 Generator notation
* Removing the use of batch, as the value of the result promise is irrelevant, only success/failure that matters

* nits

* Fixes tests, improves flow typing

src/Adapters/Storage/StorageAdapter.js

@@ -0,0 +1,53 @@
+// @flow
+export type SchemaType = any;
+export type StorageClass = any;
+export type QueryType = any;
+
+export type QueryOptions = {
+  skip?: number,
+  limit?: number,
+  acl?: string[],
+  sort?: {[string]: number},
+  count?: boolean | number,
+  keys?: string[],
+  op?: string,
+  distinct?: boolean,
+  pipeline?: any,
+  readPreference?: ?string,
+};
+
+export type UpdateQueryOptions = {
+  many?: boolean,
+  upsert?: boolean
+}
+
+export type FullQueryOptions = QueryOptions & UpdateQueryOptions;
+
+export interface StorageAdapter {
+  classExists(className: string): Promise<boolean>;
+  setClassLevelPermissions(className: string, clps: any): Promise<void>;
+  createClass(className: string, schema: SchemaType): Promise<void>;
+  addFieldIfNotExists(className: string, fieldName: string, type: any): Promise<void>;
+  deleteClass(className: string): Promise<void>;
+  deleteAllClasses(): Promise<void>;
+  deleteFields(className: string, schema: SchemaType, fieldNames: Array<string>): Promise<void>;
+  getAllClasses(): Promise<StorageClass[]>;
+  getClass(className: string): Promise<StorageClass>;
+  createObject(className: string, schema: SchemaType, object: any): Promise<any>;
+  deleteObjectsByQuery(className: string, schema: SchemaType, query: QueryType): Promise<void>;
+  updateObjectsByQuery(className: string, schema: SchemaType, query: QueryType, update: any): Promise<[any]>;
+  findOneAndUpdate(className: string, schema: SchemaType, query: QueryType, update: any): Promise<any>;
+  upsertOneObject(className: string, schema: SchemaType, query: QueryType, update: any): Promise<any>;
+  find(className: string, schema: SchemaType, query: QueryType, options: QueryOptions): Promise<[any]>;
+  ensureUniqueness(className: string, schema: SchemaType, fieldNames: Array<string>): Promise<void>;
+  count(className: string, schema: SchemaType, query: QueryType, readPreference: ?string): Promise<number>;
+  distinct(className: string, schema: SchemaType, query: QueryType, fieldName: string): Promise<any>;
+  aggregate(className: string, schema: any, pipeline: any, readPreference: ?string): Promise<any>;
+  performInitialization(options: ?any): Promise<void>;
+
+  // Indexing
+  createIndexes(className: string, indexes: any, conn: ?any): Promise<void>;
+  getIndexes(className: string, connection: ?any): Promise<void>;
+  updateSchemaWithIndexes(): Promise<void>;
+  setIndexesWithSchemaFormat(className: string, submittedIndexes: any, existingIndexes: any, fields: any, conn: ?any): Promise<void>;
+}