From 3fa50e79f12fe2b66ebd5d643ed597c6a121b198 Mon Sep 17 00:00:00 2001 From: muqiuhan Date: Sat, 3 May 2025 10:47:05 +0000 Subject: deploy: a0dad147ccf1d831c5f48d8d0e868160a23cc92c --- .../index.html" | 6 +++--- 2025/02/19/Repository-pattern-in-Typescript/index.html | 4 ++-- 2 files changed, 5 insertions(+), 5 deletions(-) (limited to '2025/02') diff --git "a/2025/02/18/Prisma-\345\205\263\347\263\273\345\236\213\346\225\260\346\215\256\345\272\223\347\232\204-Self-relations/index.html" "b/2025/02/18/Prisma-\345\205\263\347\263\273\345\236\213\346\225\260\346\215\256\345\272\223\347\232\204-Self-relations/index.html" index fda4a344..b69d4397 100644 --- "a/2025/02/18/Prisma-\345\205\263\347\263\273\345\236\213\346\225\260\346\215\256\345\272\223\347\232\204-Self-relations/index.html" +++ "b/2025/02/18/Prisma-\345\205\263\347\263\273\345\236\213\346\225\260\346\215\256\345\272\223\347\232\204-Self-relations/index.html" @@ -213,7 +213,7 @@

一对一的 self-relation 需要两个端点，即使这两个端点是同一条数据。

而在关系型数据库中，一对一的 self-relation 可以用如下 SQL 描述：

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CREATE TABLE "User" (
    id SERIAL PRIMARY KEY,
    "name" TEXT,
    "successorId" INTEGER
);

ALTER TABLE "User" ADD CONSTRAINT fk_successor_user FOREIGN KEY ("successorId") REFERENCES "User" (id);

ALTER TABLE "User" ADD CONSTRAINT successor_unique UNIQUE ("successorId");
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CREATE TABLE "User" (
    id SERIAL PRIMARY KEY,
    "name" TEXT,
    "successorId" INTEGER
);

ALTER TABLE "User" ADD CONSTRAINT fk_successor_user FOREIGN KEY ("successorId") REFERENCES "User" (id);

ALTER TABLE "User" ADD CONSTRAINT successor_unique UNIQUE ("successorId");

一对多

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model User {
  id        Int     @id @default(autoincrement())
  name      String?
  teacherId Int?
  teacher   User?   @relation("TeacherStudents", fields: [teacherId], references: [id])
  students  User[]  @relation("TeacherStudents")
}
@@ -226,7 +226,7 @@

可以通过将 teacher 字段设为 required 来要求每个 User 都有一名 teacher。

用 SQL 描述 User model：

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CREATE TABLE "User" (
    id SERIAL PRIMARY KEY,
    "name" TEXT,
    "teacherId" INTEGER
);

ALTER TABLE "User" ADD CONSTRAINT fk_teacherid_user FOREIGN KEY ("teacherId") REFERENCES "User" (id);
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CREATE TABLE "User" (
    id SERIAL PRIMARY KEY,
    "name" TEXT,
    "teacherId" INTEGER
);

ALTER TABLE "User" ADD CONSTRAINT fk_teacherid_user FOREIGN KEY ("teacherId") REFERENCES "User" (id);

teacherId 没有使用 UNIQUE 约束，这代表着多个 students 可以有同一个 teacher

多对多

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model User {
  id         Int     @id @default(autoincrement())
  name       String?
  followedBy User[]  @relation("UserFollows")
  following  User[]  @relation("UserFollows")
}
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model User {
  id         Int       @id @default(autoincrement())
  name       String?
  followedBy Follows[] @relation("followedBy")
  following  Follows[] @relation("following")
}

model Follows {
  followedBy   User @relation("followedBy", fields: [followedById], references: [id])
  followedById Int
  following    User @relation("following", fields: [followingId], references: [id])
  followingId  Int

  @@id([followingId, followedById])
}

在关系型数据库中，可以用如下 SQL 描述:

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CREATE TABLE "User" (
    id integer DEFAULT nextval('"User_id_seq"'::regclass) PRIMARY KEY,
    name text
);
CREATE TABLE "_UserFollows" (
    "A" integer NOT NULL REFERENCES "User"(id) ON DELETE CASCADE ON UPDATE CASCADE,
    "B" integer NOT NULL REFERENCES "User"(id) ON DELETE CASCADE ON UPDATE CASCADE
);
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CREATE TABLE "User" (
    id integer DEFAULT nextval('"User_id_seq"'::regclass) PRIMARY KEY,
    name text
);
CREATE TABLE "_UserFollows" (
    "A" integer NOT NULL REFERENCES "User"(id) ON DELETE CASCADE ON UPDATE CASCADE,
    "B" integer NOT NULL REFERENCES "User"(id) ON DELETE CASCADE ON UPDATE CASCADE
);

在同一模型上建立多个 self-relations

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model User {
  id         Int     @id @default(autoincrement())
  name       String?
  teacherId  Int?
  teacher    User?   @relation("TeacherStudents", fields: [teacherId], references: [id])
  students   User[]  @relation("TeacherStudents")
  followedBy User[]  @relation("UserFollows")
  following  User[]  @relation("UserFollows")
}
diff --git a/2025/02/19/Repository-pattern-in-Typescript/index.html b/2025/02/19/Repository-pattern-in-Typescript/index.html index bdd29669..d5509d8e 100644 --- a/2025/02/19/Repository-pattern-in-Typescript/index.html +++ b/2025/02/19/Repository-pattern-in-Typescript/index.html @@ -217,10 +217,10 @@
  • IGenericRepository 中定义的函数是每个 Repository 公开的通用存储函数。

    • 以上这些就是对业务中的实体的 Repository 抽象，这样就隔离开了业务和存储逻辑，例如使用 MongoDB，可以实现一个 MongoGenericRepository：

    -
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    import { Model } from 'mongoose';
    import { IGenericRepository } from '../../../core';

    export class MongoGenericRepository<T> implements IGenericRepository<T> {
      private _repository: Model<T>;
      private _populateOnFind: string[];

      constructor(repository: Model<T>, populateOnFind: string[] = []) {
        this._repository = repository;
        this._populateOnFind = populateOnFind;
      }

      getAll(): Promise<T[]> {
        return this._repository.find().populate(this._populateOnFind).exec();
      }

      get(id: any): Promise<T> {
        return this._repository.findById(id).populate(this._populateOnFind).exec();
      }

      create(item: T): Promise<T> {
        return this._repository.create(item);
      }

      update(id: string, item: T) {
        return this._repository.findByIdAndUpdate(id, item);
      }
    }
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    import { Model } from 'mongoose';
    import { IGenericRepository } from '../../../core';

    export class MongoGenericRepository<T> implements IGenericRepository<T> {
      private _repository: Model<T>;
      private _populateOnFind: string[];

      constructor(repository: Model<T>, populateOnFind: string[] = []) {
        this._repository = repository;
        this._populateOnFind = populateOnFind;
      }

      getAll(): Promise<T[]> {
        return this._repository.find().populate(this._populateOnFind).exec();
      }

      get(id: any): Promise<T> {
        return this._repository.findById(id).populate(this._populateOnFind).exec();
      }

      create(item: T): Promise<T> {
        return this._repository.create(item);
      }

      update(id: string, item: T) {
        return this._repository.findByIdAndUpdate(id, item);
      }
    }

    然后实现一个 MongoDataServices:

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    import { Injectable, OnApplicationBootstrap } from '@nestjs/common';
    import { InjectModel } from '@nestjs/mongoose';
    import { Model } from 'mongoose';
    import { IDataServices } from '../../../core';
    import { MongoGenericRepository } from './mongo-generic-repository';
    import {
      Author,
      AuthorDocument,
      Book,
      BookDocument,
      Genre,
      GenreDocument,
    } from './model';

    @Injectable()
    export class MongoDataServices
      implements IDataServices, OnApplicationBootstrap
    {
      authors: MongoGenericRepository<Author>;
      books: MongoGenericRepository<Book>;
      genres: MongoGenericRepository<Genre>;

      constructor(
        @InjectModel(Author.name)
        private AuthorRepository: Model<AuthorDocument>,
        @InjectModel(Book.name)
        private BookRepository: Model<BookDocument>,
        @InjectModel(Genre.name)
        private GenreRepository: Model<GenreDocument>,
      ) {}

      onApplicationBootstrap() {
        this.authors = new MongoGenericRepository<Author>(this.AuthorRepository);
        this.books = new MongoGenericRepository<Book>(this.BookRepository, [
          'author',
          'genre',
        ]);
        this.genres = new MongoGenericRepository<Genre>(this.GenreRepository);
      }
    }
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    import { Injectable, OnApplicationBootstrap } from '@nestjs/common';
    import { InjectModel } from '@nestjs/mongoose';
    import { Model } from 'mongoose';
    import { IDataServices } from '../../../core';
    import { MongoGenericRepository } from './mongo-generic-repository';
    import {
      Author,
      AuthorDocument,
      Book,
      BookDocument,
      Genre,
      GenreDocument,
    } from './model';

    @Injectable()
    export class MongoDataServices
      implements IDataServices, OnApplicationBootstrap
    {
      authors: MongoGenericRepository<Author>;
      books: MongoGenericRepository<Book>;
      genres: MongoGenericRepository<Genre>;

      constructor(
        @InjectModel(Author.name)
        private AuthorRepository: Model<AuthorDocument>,
        @InjectModel(Book.name)
        private BookRepository: Model<BookDocument>,
        @InjectModel(Genre.name)
        private GenreRepository: Model<GenreDocument>,
      ) {}

      onApplicationBootstrap() {
        this.authors = new MongoGenericRepository<Author>(this.AuthorRepository);
        this.books = new MongoGenericRepository<Book>(this.BookRepository, [
          'author',
          'genre',
        ]);
        this.genres = new MongoGenericRepository<Genre>(this.GenreRepository);
      }
    }

    Sunday, March 30, 2025 7:58 PM:

    -- cgit v1.2.3