理解建造者模式

代码示例

1new QueryBuilder()
2  .withText('foo')
3  .inCategory('books')
4  .paginate(1, 20)
5  .build()

Node.js

1class SearchQueryBuilder {
2  constructor() {
3    this.query = {
4      filters: {},
5      pagination: {}
6    };
7  }
8
9  withText(text) {
10    this.query.filters.text = text;
11    return this;
12  }
13
14  inCategory(category) {
15    this.query.filters.category = category;
16    return this;
17  }
18
19  withTags(tags) {
20    this.query.filters.tags = tags;
21    return this;
22  }
23
24  paginate(page, limit) {
25    this.query.pagination = { page, limit };
26    return this;
27  }
28
29  build() {
30    return this.query;
31  }
32}
33
34// Usage
35const query = new SearchQueryBuilder()
36  .withText('node.js')
37  .inCategory('books')
38  .withTags(['design', 'backend'])
39  .paginate(2, 10)
40  .build();
41
42console.log(query);

TypeScript

1type Query = {
2  filters: {
3    text?: string;
4    category?: string;
5    tags?: string[];
6  };
7  pagination: {
8    page?: number;
9    limit?: number;
10  };
11};
12
13class SearchQueryBuilder {
14  private query: Query = {
15    filters: {},
16    pagination: {}
17  };
18
19  withText(text: string): this {
20    this.query.filters.text = text;
21    return this;
22  }
23
24  inCategory(category: string): this {
25    this.query.filters.category = category;
26    return this;
27  }
28
29  withTags(tags: string[]): this {
30    this.query.filters.tags = tags;
31    return this;
32  }
33
34  paginate(page: number, limit: number): this {
35    this.query.pagination = { page, limit };
36    return this;
37  }
38
39  build(): Query {
40    return this.query;
41  }
42}
43
44// Usage
45const query = new SearchQueryBuilder()
46  .withText('node.js')
47  .inCategory('books')
48  .withTags(['design', 'backend'])
49  .paginate(2, 10)
50  .build();
51
52console.log(query);