创建自定义驱动程序

如果你想使用当前不支持的数据库，你可以实现自己的驱动程序。为此，你需要设计 4 个类：

¥If you want to use database that is not currently supported, you can implement your own driver. To do so, you will need to design 4 classes:

平台

¥Platform

平台是一个提供有关给定驱动程序可用功能的信息的类：

¥Platform is a class that provides information about available features of given driver:

import { Platform } from '@mikro-orm/core';

export class MyCustomPlatform extends Platform {

  protected abstract schemaHelper: MyCustomSchemaHelper;

  // here you can override default settings
  usesPivotTable(): boolean;
  supportsTransactions(): boolean;
  supportsSavePoints(): boolean;
  getNamingStrategy(): { new (): NamingStrategy; };
  getIdentifierQuoteCharacter(): string;
  getParameterPlaceholder(index?: number): string;
  usesReturningStatement(): boolean;
  normalizePrimaryKey<T = number | string>(data: IPrimaryKey): T;
  denormalizePrimaryKey(data: IPrimaryKey): IPrimaryKey;
  getSerializedPrimaryKeyField(field: string): string;

}

SchemaHelper

平台的一部分是 SchemaHelper，它提供有关如何构建架构的信息。

¥Part of platform is a SchemaHelper, that provides information about how to build schema.

import { SchemaHelper } from '@mikro-orm/core';

export class MyCustomSchemaHelper extends SchemaHelper {

  // here you can override default settings
  getIdentifierQuoteCharacter(): string;
  getSchemaBeginning(): string;
  getSchemaEnd(): string;
  getSchemaTableEnd(): string;
  getAutoIncrementStatement(meta: EntityMetadata): string;
  getPrimaryKeySubtype(meta: EntityMetadata): string;
  getTypeDefinition(prop: EntityProperty, types?: Record<string, string>, lengths?: Record<string, number>): string;
  getUnsignedSuffix(prop: EntityProperty): string;
  supportsSchemaConstraints(): boolean;
  supportsSchemaMultiAlter(): boolean;
  supportsSequences(): boolean;
  quoteIdentifier(field: string): string;
  dropTable(meta: EntityMetadata): string;
  indexForeignKeys(): boolean;

}

连接

¥Connection

下一部分是连接封装器，它将负责查询数据库：

¥Next part is connection wrapper, that will be responsible for querying the database:

import { Connection } from '@mikro-orm/core';

export class MyCustomConnection extends Connection {

  // implement abstract methods
  connect(): Promise<void>;
  isConnected(): Promise<boolean>;
  close(force?: boolean): Promise<void>;
  getDefaultClientUrl(): string;
  execute(query: string, params?: any[], method?: 'all' | 'get' | 'run'): Promise<QueryResult | any | any[]>;

}

驱动程序

¥Driver

最后一部分是驱动程序，负责使用连接将更改持久保存到数据库。如果你正在构建 SQL 驱动程序，扩展 AbstractSqlDriver 可能会很方便，如果不是，请扩展 DatabaseDriver 抽象类。

¥Last part is driver, that is responsible for using the connection to persist changes to database. If you are building SQL driver, it might be handy to extend AbstractSqlDriver, if not, extend DatabaseDriver abstract class.

如果你想要拥有绝对控制权，你可以通过 IDatabaseDriver 接口自己实现整个驱动程序。

¥If you want to have absolute control, you can implement the whole driver yourself via IDatabaseDriver interface.

import { DatabaseDriver } from '@mikro-orm/core';

export class MyCustomDriver extends DatabaseDriver {

  // initialize connection and platform
  protected readonly connection = new MyCustomConnection(this.config);
  protected readonly platform = new MyCustomPlatform;

  // and implement abstract methods
  find<T extends AnyEntity>(entityName: string, where: FilterQuery<T>, populate?: string[], orderBy?: Record<string, QueryOrder>, limit?: number, offset?: number): Promise<T[]>;
  findOne<T extends AnyEntity>(entityName: string, where: FilterQuery<T> | string, populate: string[]): Promise<T | null>;
  nativeInsert<T extends AnyEntityType<T>>(entityName: string, data: EntityData<T>): Promise<QueryResult>;
  nativeUpdate<T extends AnyEntity>(entityName: string, where: FilterQuery<T> | IPrimaryKey, data: EntityData<T>): Promise<QueryResult>;
  nativeDelete<T extends AnyEntity>(entityName: string, where: FilterQuery<T> | IPrimaryKey): Promise<QueryResult>;
  count<T extends AnyEntity>(entityName: string, where: FilterQuery<T>): Promise<number>;

}