feat: add support for STI on EntitySchema (#9834)

* feat: add support for STI on EntitySchema

Closes: #9833

* fix: run prettier

---------

Co-authored-by: Umed Khudoiberdiev <pleerock.me@gmail.com>

docs/separating-entity-definition.md

@@ -230,6 +230,112 @@ export const UserEntitySchema = new EntitySchema<User>({
 
 Be sure to add the `extended` columns also to the `Category` interface (e.g., via `export interface Category extend BaseEntity`).
 
+### Single Table Inheritance
+
+In order to use [Single Table Inheritance](entity-inheritance.md#single-table-inheritance):
+
+1. Add the `inheritance` option to the **parent** class schema, specifying the inheritance pattern ("STI") and the
+   **discriminator** column, which will store the name of the *child* class on each row
+2. Set the `type: "entity-child"` option for all **children** classes' schemas, while extending the *parent* class
+   columns using the spread operator syntax described above
+
+```ts
+// entity.ts
+
+export abstract class Base {
+    id!: number
+    type!: string
+    createdAt!: Date
+    updatedAt!: Date
+}
+
+export class A extends Base {
+    constructor(public a: boolean) {
+        super()
+    }
+}
+
+export class B extends Base {
+    constructor(public b: number) {
+        super()
+    }
+}
+
+export class C extends Base {
+    constructor(public c: string) {
+        super()
+    }
+}
+```
+
+```ts
+// schema.ts
+
+const BaseSchema = new EntitySchema<Base>({
+    target: Base,
+    name: "Base",
+    columns: {
+        id: {
+            type: Number,
+            primary: true,
+            generated: "increment",
+        },
+        type: {
+            type: String,
+        },
+        createdAt: {
+            type: Date,
+            createDate: true,
+        },
+        updatedAt: {
+            type: Date,
+            updateDate: true,
+        },
+    },
+    // NEW: Inheritance options
+    inheritance: {
+        pattern: "STI",
+        column: "type",
+    },
+})
+
+const ASchema = new EntitySchema<A>({
+    target: A,
+    name: "A",
+    type: "entity-child",
+    columns: {
+        ...BaseSchema.options.columns,
+        a: {
+            type: Boolean,
+        },
+    },
+})
+
+const BSchema = new EntitySchema<B>({
+    target: B,
+    name: "B",
+    type: "entity-child",
+    columns: {
+        ...BaseSchema.options.columns,
+        b: {
+            type: Number,
+        },
+    },
+})
+
+const CSchema = new EntitySchema<C>({
+    target: C,
+    name: "C",
+    type: "entity-child",
+    columns: {
+        ...BaseSchema.options.columns,
+        c: {
+            type: String,
+        },
+    },
+})
+```
+
 ## Using Schemas to Query / Insert Data
 
 Of course, you can use the defined schemas in your repositories or entity manager as you would use the decorators.

package-lock.json

@@ -1,7 +1,7 @@
 {
   "name": "typeorm",
   "version": "0.3.12",
-  "lockfileVersion": 2,
+  "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {

src/entity-schema/EntitySchemaInheritanceOptions.ts

@@ -0,0 +1,13 @@
+import { ColumnOptions } from "../decorator/options/ColumnOptions"
+
+export interface EntitySchemaInheritanceOptions {
+    /**
+     * Inheritance pattern.
+     */
+    pattern?: "STI"
+
+    /**
+     * Inheritance discriminator column.
+     */
+    column?: string | ColumnOptions
+}

src/entity-schema/EntitySchemaOptions.ts

@@ -11,17 +11,13 @@ import { TableType } from "../metadata/types/TableTypes"
 import { EntitySchemaUniqueOptions } from "./EntitySchemaUniqueOptions"
 import { EntitySchemaCheckOptions } from "./EntitySchemaCheckOptions"
 import { EntitySchemaExclusionOptions } from "./EntitySchemaExclusionOptions"
+import { EntitySchemaInheritanceOptions } from "./EntitySchemaInheritanceOptions"
 import { EntitySchemaRelationIdOptions } from "./EntitySchemaRelationIdOptions"
 
 /**
  * Interface for entity metadata mappings stored inside "schemas" instead of models decorated by decorators.
  */
 export class EntitySchemaOptions<T> {
-    /**
-     * Name of the schema it extends.
-     */
-    extends?: string
-
     /**
      * Target bind to this entity schema. Optional.
      */
@@ -123,4 +119,9 @@ export class EntitySchemaOptions<T> {
      * View expression.
      */
     expression?: string | ((connection: DataSource) => SelectQueryBuilder<any>)
+
+    /**
+     * Inheritance options.
+     */
+    inheritance?: EntitySchemaInheritanceOptions
 }

src/entity-schema/EntitySchemaTransformer.ts

@@ -16,6 +16,7 @@ import { ExclusionMetadataArgs } from "../metadata-args/ExclusionMetadataArgs"
 import { EntitySchemaColumnOptions } from "./EntitySchemaColumnOptions"
 import { EntitySchemaOptions } from "./EntitySchemaOptions"
 import { EntitySchemaEmbeddedError } from "./EntitySchemaEmbeddedError"
+import { InheritanceMetadataArgs } from "../metadata-args/InheritanceMetadataArgs"
 import { RelationIdMetadataArgs } from "../metadata-args/RelationIdMetadataArgs"
 
 /**
@@ -50,6 +51,20 @@ export class EntitySchemaTransformer {
             }
             metadataArgsStorage.tables.push(tableMetadata)
 
+            const { inheritance } = options
+
+            if (inheritance) {
+                metadataArgsStorage.inheritances.push({
+                    target: options.target,
+                    pattern: inheritance.pattern ?? "STI",
+                    column: inheritance.column
+                        ? typeof inheritance.column === "string"
+                            ? { name: inheritance.column }
+                            : inheritance.column
+                        : undefined,
+                } as InheritanceMetadataArgs)
+            }
+
             this.transformColumnsRecursive(options, metadataArgsStorage)
         })
 

test/github-issues/9833/entity/A.ts

@@ -0,0 +1,7 @@
+import { Base } from "./Base"
+
+export class A extends Base {
+    constructor(public a: boolean) {
+        super()
+    }
+}

test/github-issues/9833/entity/B.ts

@@ -0,0 +1,7 @@
+import { Base } from "./Base"
+
+export class B extends Base {
+    constructor(public b: number) {
+        super()
+    }
+}

test/github-issues/9833/entity/Base.ts

@@ -0,0 +1,6 @@
+export abstract class Base {
+    id!: number
+    type!: string
+    createdAt!: Date
+    updatedAt!: Date
+}

test/github-issues/9833/entity/C.ts

@@ -0,0 +1,7 @@
+import { Base } from "./Base"
+
+export class C extends Base {
+    constructor(public c: string) {
+        super()
+    }
+}

test/github-issues/9833/entity/index.ts

@@ -0,0 +1,5 @@
+export * from "./Base"
+
+export * from "./A"
+export * from "./B"
+export * from "./C"

test/github-issues/9833/issue-9833.ts

@@ -0,0 +1,65 @@
+import "reflect-metadata"
+
+import { expect } from "chai"
+
+import {
+    createTestingConnections,
+    closeTestingConnections,
+    reloadTestingDatabases,
+} from "../../utils/test-utils"
+import { DataSource } from "../../../src/data-source/DataSource"
+import { Repository } from "../../../src"
+
+import { Base, A, B, C } from "./entity"
+import { BaseSchema, ASchema, BSchema, CSchema } from "./schema"
+
+describe("github issues > #9833 Add support for Single Table Inheritance when using Entity Schemas", () => {
+    let dataSources: DataSource[]
+
+    before(
+        async () =>
+            (dataSources = await createTestingConnections({
+                entities: [BaseSchema, ASchema, BSchema, CSchema],
+                schemaCreate: true,
+                dropSchema: true,
+                enabledDrivers: [
+                    "better-sqlite3",
+                    "cockroachdb",
+                    "mariadb",
+                    "mssql",
+                    "mysql",
+                    "oracle",
+                    "postgres",
+                    "spanner",
+                    "sqlite",
+                ],
+            })),
+    )
+
+    beforeEach(() => reloadTestingDatabases(dataSources))
+
+    after(() => closeTestingConnections(dataSources))
+
+    it("should instantiate concrete entities when using EntitySchema", () =>
+        Promise.all(
+            dataSources.map(async (dataSource) => {
+                // Arrange
+                const repository: Repository<Base> =
+                    dataSource.getRepository(Base)
+
+                const entities: Base[] = [new A(true), new B(42), new C("foo")]
+
+                await repository.save(entities)
+
+                // Act
+                const loadedEntities = await repository.find({
+                    order: { type: "ASC" },
+                })
+
+                // Assert
+                expect(loadedEntities[0]).to.be.instanceOf(A)
+                expect(loadedEntities[1]).to.be.instanceOf(B)
+                expect(loadedEntities[2]).to.be.instanceOf(C)
+            }),
+        ))
+})

test/github-issues/9833/schema/A.ts

@@ -0,0 +1,17 @@
+import { EntitySchema } from "../../../../src"
+
+import { A } from "../entity"
+
+import { BaseSchema } from "./Base"
+
+export const ASchema = new EntitySchema<A>({
+    target: A,
+    name: "A",
+    type: "entity-child",
+    columns: {
+        ...BaseSchema.options.columns,
+        a: {
+            type: Boolean,
+        },
+    },
+})

test/github-issues/9833/schema/B.ts

@@ -0,0 +1,17 @@
+import { EntitySchema } from "../../../../src"
+
+import { B } from "../entity"
+
+import { BaseSchema } from "./Base"
+
+export const BSchema = new EntitySchema<B>({
+    target: B,
+    name: "B",
+    type: "entity-child",
+    columns: {
+        ...BaseSchema.options.columns,
+        b: {
+            type: Number,
+        },
+    },
+})

test/github-issues/9833/schema/Base.ts

@@ -0,0 +1,30 @@
+import { EntitySchema } from "../../../../src"
+
+import { Base } from "../entity"
+
+export const BaseSchema = new EntitySchema<Base>({
+    target: Base,
+    name: "Base",
+    columns: {
+        id: {
+            type: Number,
+            primary: true,
+            generated: "increment",
+        },
+        type: {
+            type: String,
+        },
+        createdAt: {
+            type: Date,
+            createDate: true,
+        },
+        updatedAt: {
+            type: Date,
+            updateDate: true,
+        },
+    },
+    inheritance: {
+        pattern: "STI",
+        column: "type",
+    },
+})

test/github-issues/9833/schema/C.ts

@@ -0,0 +1,17 @@
+import { EntitySchema } from "../../../../src"
+
+import { C } from "../entity"
+
+import { BaseSchema } from "./Base"
+
+export const CSchema = new EntitySchema<C>({
+    target: C,
+    name: "C",
+    type: "entity-child",
+    columns: {
+        ...BaseSchema.options.columns,
+        c: {
+            type: String,
+        },
+    },
+})

test/github-issues/9833/schema/index.ts

@@ -0,0 +1,5 @@
+export * from "./Base"
+
+export * from "./A"
+export * from "./B"
+export * from "./C"