161 lines
7.0 KiB
Plaintext
161 lines
7.0 KiB
Plaintext
---
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title: 关系
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description: 使用双向 MANY_TO_ONE / ONE_TO_MANY 关系将对象连接在一起。
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icon: diagram-project
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---
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关系用于将两个对象连接在一起。 在 Twenty 中，关系始终是 **双向的**——每个关系都有两侧，每一侧都作为一个字段声明，并引用另一侧。
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| 关系类型 | 描述 | 是否有外键？ |
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| ------------- | ------------------- | ------------------- |
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| `MANY_TO_ONE` | 该对象的多条记录指向目标对象的一条记录 | 是（`joinColumnName`） |
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| `ONE_TO_MANY` | 该对象的一条记录拥有目标对象的多条记录 | 否（反向侧） |
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## 关系如何工作
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每个关系都需要两个相互引用的字段：
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1. **MANY_TO_ONE** 侧——位于持有外键的对象上。
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2. **ONE_TO_MANY** 侧——位于拥有集合的对象上。
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两个字段都使用 `FieldType.RELATION`，并通过 `relationTargetFieldMetadataUniversalIdentifier` 相互交叉引用。
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## 示例：Post Card 拥有多个收件人
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一个 `PostCard` 可以发送给多个 `PostCardRecipient` 记录。 每个收件人只隶属于一张 PostCard。
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**步骤 1：在 PostCard 上定义 ONE_TO_MANY 侧**（“一”侧）：
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```ts src/fields/post-card-recipients-on-post-card.field.ts
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import { defineField, FieldType, RelationType } from 'twenty-sdk/define';
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import { POST_CARD_UNIVERSAL_IDENTIFIER } from '../objects/post-card.object';
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import { POST_CARD_RECIPIENT_UNIVERSAL_IDENTIFIER } from '../objects/post-card-recipient.object';
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// Export so the other side can reference it
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export const POST_CARD_RECIPIENTS_FIELD_ID = 'a1111111-1111-1111-1111-111111111111';
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// Import from the other side
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import { POST_CARD_FIELD_ID } from './post-card-on-post-card-recipient.field';
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export default defineField({
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universalIdentifier: POST_CARD_RECIPIENTS_FIELD_ID,
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objectUniversalIdentifier: POST_CARD_UNIVERSAL_IDENTIFIER,
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type: FieldType.RELATION,
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name: 'postCardRecipients',
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label: 'Post Card Recipients',
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icon: 'IconUsers',
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relationTargetObjectMetadataUniversalIdentifier: POST_CARD_RECIPIENT_UNIVERSAL_IDENTIFIER,
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relationTargetFieldMetadataUniversalIdentifier: POST_CARD_FIELD_ID,
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universalSettings: {
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relationType: RelationType.ONE_TO_MANY,
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},
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});
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```
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**步骤 2：在 PostCardRecipient 上定义 MANY_TO_ONE 侧**（“多”侧——持有外键）：
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```ts src/fields/post-card-on-post-card-recipient.field.ts
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import { defineField, FieldType, RelationType, OnDeleteAction } from 'twenty-sdk/define';
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import { POST_CARD_UNIVERSAL_IDENTIFIER } from '../objects/post-card.object';
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import { POST_CARD_RECIPIENT_UNIVERSAL_IDENTIFIER } from '../objects/post-card-recipient.object';
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// Export so the other side can reference it
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export const POST_CARD_FIELD_ID = 'b2222222-2222-2222-2222-222222222222';
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// Import from the other side
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import { POST_CARD_RECIPIENTS_FIELD_ID } from './post-card-recipients-on-post-card.field';
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export default defineField({
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universalIdentifier: POST_CARD_FIELD_ID,
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objectUniversalIdentifier: POST_CARD_RECIPIENT_UNIVERSAL_IDENTIFIER,
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type: FieldType.RELATION,
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name: 'postCard',
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label: 'Post Card',
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icon: 'IconMail',
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relationTargetObjectMetadataUniversalIdentifier: POST_CARD_UNIVERSAL_IDENTIFIER,
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relationTargetFieldMetadataUniversalIdentifier: POST_CARD_RECIPIENTS_FIELD_ID,
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universalSettings: {
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relationType: RelationType.MANY_TO_ONE,
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onDelete: OnDeleteAction.CASCADE,
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joinColumnName: 'postCardId',
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},
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});
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```
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<Note>
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\*\*循环导入：\*\*两个关系字段相互引用对方的 `universalIdentifier`。 为避免循环导入问题，请在各自文件中将字段 ID 作为具名常量导出，并在另一个文件中导入它们。 构建系统会在编译时解析这些引用。
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</Note>
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## 与标准对象建立关系
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要与内置的 Twenty 对象（Person、Company 等）建立关系，请使用 `STANDARD_OBJECT_UNIVERSAL_IDENTIFIERS`：
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```ts src/fields/person-on-self-hosting-user.field.ts
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import {
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defineField,
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FieldType,
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RelationType,
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OnDeleteAction,
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STANDARD_OBJECT_UNIVERSAL_IDENTIFIERS,
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} from 'twenty-sdk/define';
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import { SELF_HOSTING_USER_UNIVERSAL_IDENTIFIER } from '../objects/self-hosting-user.object';
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export const PERSON_FIELD_ID = 'c3333333-3333-3333-3333-333333333333';
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export const SELF_HOSTING_USER_REVERSE_FIELD_ID = 'd4444444-4444-4444-4444-444444444444';
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export default defineField({
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universalIdentifier: PERSON_FIELD_ID,
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objectUniversalIdentifier: SELF_HOSTING_USER_UNIVERSAL_IDENTIFIER,
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type: FieldType.RELATION,
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name: 'person',
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label: 'Person',
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description: 'Person matching with the self hosting user',
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isNullable: true,
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relationTargetObjectMetadataUniversalIdentifier:
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STANDARD_OBJECT_UNIVERSAL_IDENTIFIERS.person.universalIdentifier,
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relationTargetFieldMetadataUniversalIdentifier: SELF_HOSTING_USER_REVERSE_FIELD_ID,
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universalSettings: {
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relationType: RelationType.MANY_TO_ONE,
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onDelete: OnDeleteAction.SET_NULL,
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joinColumnName: 'personId',
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},
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});
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```
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## 关系字段属性
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| 属性 | 必填 | 描述 |
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| ------------------------------------------------- | ---------------- | -------------------------------------------------------------- |
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| `type` | 是 | 必须为 `FieldType.RELATION` |
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| `relationTargetObjectMetadataUniversalIdentifier` | 是 | 目标对象的 `universalIdentifier` |
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| `relationTargetFieldMetadataUniversalIdentifier` | 是 | 目标对象上匹配字段的 `universalIdentifier` |
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| `universalSettings.relationType` | 是 | `RelationType.MANY_TO_ONE` 或 `RelationType.ONE_TO_MANY` |
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| `universalSettings.onDelete` | 仅适用于 MANY_TO_ONE | 当被引用的记录被删除时的处理方式：`CASCADE`、`SET_NULL`、`RESTRICT` 或 `NO_ACTION` |
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| `universalSettings.joinColumnName` | 仅适用于 MANY_TO_ONE | 外键的数据库列名（例如，`postCardId`） |
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## 内联关系字段
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你也可以直接在 [`defineObject`](/l/zh/developers/extend/apps/data/objects) 中声明关系。 以内联方式声明时，省略 `objectUniversalIdentifier`——它会从父对象继承：
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```ts
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export default defineObject({
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universalIdentifier: '...',
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nameSingular: 'postCardRecipient',
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// ...
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fields: [
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{
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universalIdentifier: POST_CARD_FIELD_ID,
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type: FieldType.RELATION,
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name: 'postCard',
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label: 'Post Card',
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relationTargetObjectMetadataUniversalIdentifier: POST_CARD_UNIVERSAL_IDENTIFIER,
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relationTargetFieldMetadataUniversalIdentifier: POST_CARD_RECIPIENTS_FIELD_ID,
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universalSettings: {
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relationType: RelationType.MANY_TO_ONE,
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onDelete: OnDeleteAction.CASCADE,
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joinColumnName: 'postCardId',
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},
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},
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// … other fields
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],
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});
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```
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