如何防止装饰者在TypeScript中导入节点模块？

Question

我试图在打字稿中使用typeorm库在TypeScript 2 Express服务器和Angular 2之间创建DTO/DAO模式。

为了简洁起见，我将这些对象称为DTO，但它们只是一堆字段和注释。

import {autoserialize} from "cerialize"; 
import {DTOReport} from "./reports.dto"; 

import { PrimaryGeneratedColumn} from "typeorm/decorator/columns/PrimaryGeneratedColumn" 
import { CreateDateColumn } from "typeorm/decorator/columns/CreateDateColumn"; 
import { Column } from "typeorm/decorator/columns/Column"; 
import { JoinColumn } from "typeorm/decorator/relations/JoinColumn"; 
import { OneToOne } from "typeorm/decorator/relations/OneToOne"; 
import { ManyToOne } from "typeorm/decorator/relations/ManyToOne"; 
import { OneToMany } from "typeorm/decorator/relations/OneToMany"; 
import { Table } from "typeorm/decorator/tables/Table"; 
import { ColumnTypes } from "typeorm/metadata/types/ColumnTypes"; 

@Table() 
export class DTOSourceFile { 
    @PrimaryGeneratedColumn() 
    @autoserialize 
    id: number; 

    @Column() 
    @autoserialize 
    locationURL: string; 

    @CreateDateColumn() 
    @autoserialize 
    createdAt: Date; 

    @OneToMany(type => DTOReport, report => report.source, {nullable: true}) 
    @autoserialize report: DTOReport; 
    @autoserialize reportId: number; 

    @Column(ColumnTypes.TEXT) 
    @autoserialize 
    originalname: string; 

    @Column(ColumnTypes.JSON) 
    @autoserialize 
    mutler: string; 
} 

我小心地只导入装饰器。但是，在编译时，我看到一个请求返回到根index.ts文件。

"use strict"; 
const ColumnTypes_1 = require("../../metadata/types/ColumnTypes"); 
const ColumnTypeUndefinedError_1 = require("../error/ColumnTypeUndefinedError"); 
const index_1 = require("../../index"); // < --- THIS 
const PrimaryColumnCannotBeNullableError_1 = require("../error/PrimaryColumnCannotBeNullableError"); 
/** 
* Column decorator is used to mark a specific class property as a table column. 
* Only properties decorated with this decorator will be persisted to the database when entity be saved. 
* Primary columns also creates a PRIMARY KEY for this column in a db. 
*/ 
function PrimaryColumn(typeOrOptions, options) { 
    let type; 
    if (typeof typeOrOptions === "string") { 
     type = typeOrOptions; 
    } 
    else { 
     options = typeOrOptions; 
    } 
    return function (object, propertyName) { 
     const reflectedType = ColumnTypes_1.ColumnTypes.typeToString(Reflect.getMetadata("design:type", object, propertyName)); 
     // if type is not given implicitly then try to guess it 
     if (!type) 
      type = ColumnTypes_1.ColumnTypes.determineTypeFromFunction(Reflect.getMetadata("design:type", object, propertyName)); 
     // if column options are not given then create a new empty options 
     if (!options) 
      options = {}; 
     // check if there is no type in column options then set type from first function argument, or guessed one 
     if (!options.type) 
      options = Object.assign({ type: type }, options); 
     // if we still don't have a type then we need to give error to user that type is required 
     if (!options.type) 
      throw new ColumnTypeUndefinedError_1.ColumnTypeUndefinedError(object, propertyName); 
     // check if column is not nullable, because we cannot allow a primary key to be nullable 
     if (options.nullable) 
      throw new PrimaryColumnCannotBeNullableError_1.PrimaryColumnCannotBeNullableError(object, propertyName); 
     // implicitly set a primary to column options 
     options = Object.assign({ primary: true }, options); 
     // create and register a new column metadata 
     const args = { 
      target: object.constructor, 
      propertyName: propertyName, 
      propertyType: reflectedType, 
      mode: "regular", 
      options: options 
     }; 
     index_1.getMetadataArgsStorage().columns.add(args); // < --- THIS 
    }; 
} 
exports.PrimaryColumn = PrimaryColumn; 

//# sourceMappingURL=PrimaryColumn.js.map 

Angular 2的webpack编译器产生的错误清楚地显示了问题，因为它会尝试加载节点依赖关系。

WARNING in ./~/typeorm/driver/sqlserver/SqlServerDriver.js 
Module not found: Error: Can't resolve 'mssql' in '/Users/jmurphy/projects/ubq/web/node_modules/typeorm/driver/sqlserver' 
@ ./~/typeorm/driver/sqlserver/SqlServerDriver.js 256:25-41 
@ ./~/typeorm/connection/ConnectionManager.js 
@ ./~/typeorm/index.js 
@ ./~/typeorm/decorator/columns/PrimaryGeneratedColumn.js 
@ ./src/app/dtos/lens.dto.ts 
@ ./src/app/lens/lens.component.ts 
@ ./src/app/app.module.ts 
@ ./src/app/index.ts 
@ ./src/main.ts 
@ multi main 
Child html-webpack-plugin for "index.html": 
     Asset  Size Chunks  Chunk Names 
    index.html 2.88 kB  0 
webpack: bundle is now VALID. 

有没有一种方法可以让TypeORM装饰在浏览器项目中存在，但不尝试加载节点的依赖？

链接：

TypeORM来源： https://github.com/typeorm/typeorm/blob/master/src/decorator/columns/PrimaryColumn.ts

Answer 1

我觉得这个库没有被设计在Web浏览器的工作，但也许有一个解决方案。装饰器使用getMetadataArgsStorage函数，其声明为/index.ts。 /index.ts导入了很多导致您遇到问题的事情。

您可以看到heregetMetadataArgsStorage函数如何使用defaultContainer和MetadataArgsStorage。

如果getMetadataArgsStorage从index.ts转移到一个新的文件，也许它会工作你，但是你要需要一个PR发送到GitHub上的项目。

问题是this line因为ConnectionManager进口的所有驱动程序：

import * as fs from "fs"; 
import {Connection} from "./Connection"; 
import {ConnectionNotFoundError} from "./error/ConnectionNotFoundError"; 
import {MysqlDriver} from "../driver/mysql/MysqlDriver"; 
import {ConnectionOptions} from "./ConnectionOptions"; 
import {DriverOptions} from "../driver/DriverOptions"; 
import {Driver} from "../driver/Driver"; 
import {MissingDriverError} from "./error/MissingDriverError"; 
import {PostgresDriver} from "../driver/postgres/PostgresDriver"; 
import {AlreadyHasActiveConnectionError} from "./error/AlreadyHasActiveConnectionError"; 
import {Logger} from "../logger/Logger"; 
import {SqliteDriver} from "../driver/sqlite/SqliteDriver"; 
import {OracleDriver} from "../driver/oracle/OracleDriver"; 
import {SqlServerDriver} from "../driver/sqlserver/SqlServerDriver"; 
import {OrmUtils} from "../util/OrmUtils"; 
import {CannotDetermineConnectionOptionsError} from "./error/CannotDetermineConnectionOptionsError"; 

/** 
* ConnectionManager is used to store and manage all these different connections. 
* It also provides useful factory methods to simplify connection creation. 
*/ 
export class ConnectionManager { 
// ... 

我建议你到你的使用情况解释typeorm的作者。也可能会提到，如果不是所有的驱动程序总是默认导入，那将会很好。最好只加载所需的驱动程序（在你的情况下都不是）。