feat: new virtual column decorator (#9339)

* feat: implement new calculated decorator This new feature change bahviour of typeorm to allow use new calculated decorator Closes #9323 * feat: implement new virtual decorator This new feature change bahviour of typeorm to allow use new virtual decorator Closes #9323 * feat: Implement new virtual decorator This new feature change bahviour of typeorm to allow use new virtual decorator Closes #9323 * feat: implement new virtual decorator This new feature change bahviour of typeorm to allow use new calculated decorator Closes #9323 * feat: implement new virtual decorator This new feature change behavior of typeorm to allow use of the new virtual column decorator Closes #9323
typeorm · Sep 20, 2022 · d305e5f · d305e5f
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diff --git a/docs/decorator-reference.md b/docs/decorator-reference.md
@@ -14,6 +14,7 @@
         -   [`@DeleteDateColumn`](#deletedatecolumn)
         -   [`@VersionColumn`](#versioncolumn)
         -   [`@Generated`](#generated)
+        -   [`@VirtualColumn`](#virtualcolumn)
     -   [Relation decorators](#relation-decorators)
         -   [`@OneToOne`](#onetoone)
         -   [`@ManyToOne`](#manytoone)
@@ -374,6 +375,34 @@ export class User {
 
 Value will be generated only once, before inserting the entity into the database.
 
+#### `@VirtualColumn`
+
+Special column that is never saved to the database and thus acts as a readonly property.
+Each time you call `find` or `findOne` from the entity manager, the value is recalculated based on the query function that was provided in the VirtualColumn Decorator. The alias argument passed to the query references the exact entity alias of the generated query behind the scenes.
+
+```typescript
+@Entity({ name: "companies", alias: "COMP" })
+export class Company extends BaseEntity {
+  @PrimaryColumn("varchar", { length: 50 })
+  name: string;
+
+  @VirtualColumn({ query: (alias) => `SELECT COUNT("name") FROM "employees" WHERE "companyName" = ${alias}.name` })
+  totalEmployeesCount: number;
+
+  @OneToMany((type) => Employee, (employee) => employee.company)
+  employees: Employee[];
+}
+
+@Entity({ name: "employees" })
+export class Employee extends BaseEntity {
+  @PrimaryColumn("varchar", { length: 50 })
+  name: string;
+
+  @ManyToOne((type) => Company, (company) => company.employees)
+  company: Company;
+}
+```
+
 ## Relation decorators
 
 #### `@OneToOne`

diff --git a/src/decorator/columns/VirtualColumn.ts b/src/decorator/columns/VirtualColumn.ts
@@ -0,0 +1,74 @@
+import { ColumnType } from "../../driver/types/ColumnTypes"
+import { ColumnTypeUndefinedError } from "../../error"
+import { getMetadataArgsStorage } from "../../globals"
+import { ColumnMetadataArgs } from "../../metadata-args/ColumnMetadataArgs"
+import { VirtualColumnOptions } from "../options/VirtualColumnOptions"
+/**
+ * VirtualColumn decorator is used to mark a specific class property as a Virtual column.
+ */
+export function VirtualColumn(options: VirtualColumnOptions): PropertyDecorator
+
+/**
+ * VirtualColumn decorator is used to mark a specific class property as a Virtual column.
+ */
+export function VirtualColumn(
+    typeOrOptions: ColumnType,
+    options: VirtualColumnOptions,
+): PropertyDecorator
+
+/**
+ * VirtualColumn decorator is used to mark a specific class property as a Virtual column.
+ */
+export function VirtualColumn(
+    typeOrOptions?: ColumnType | VirtualColumnOptions,
+    options?: VirtualColumnOptions,
+): PropertyDecorator {
+    return function (object: Object, propertyName: string) {
+        // normalize parameters
+        let type: ColumnType | undefined
+        if (typeof typeOrOptions === "string") {
+            type = <ColumnType>typeOrOptions
+        } else {
+            options = <VirtualColumnOptions>typeOrOptions
+            type = options.type
+        }
+
+        if (!options?.query) {
+            throw new Error(
+                "Column options must be defined for calculated columns.",
+            )
+        }
+
+        // if type is not given explicitly then try to guess it
+        const reflectMetadataType =
+            Reflect && (Reflect as any).getMetadata
+                ? (Reflect as any).getMetadata(
+                      "design:type",
+                      object,
+                      propertyName,
+                  )
+                : undefined
+        if (!type && reflectMetadataType)
+            // if type is not given explicitly then try to guess it
+            type = reflectMetadataType
+
+        // check if there is no type in column options then set type from first function argument, or guessed one
+        if (type) options.type = type
+
+        // specify HSTORE type if column is HSTORE
+        if (options.type === "hstore" && !options.hstoreType)
+            options.hstoreType =
+                reflectMetadataType === Object ? "object" : "string"
+
+        // 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(object, propertyName)
+
+        getMetadataArgsStorage().columns.push({
+            target: object.constructor,
+            propertyName: propertyName,
+            mode: "virtual-property",
+            options: options || {},
+        } as ColumnMetadataArgs)
+    }
+}
diff --git a/src/decorator/options/VirtualColumnOptions.ts b/src/decorator/options/VirtualColumnOptions.ts
@@ -0,0 +1,31 @@
+import { ColumnType } from "../../driver/types/ColumnTypes"
+import { ValueTransformer } from "./ValueTransformer"
+
+/**
+ * Describes all calculated column's options.
+ */
+export interface VirtualColumnOptions {
+    /**
+     * Column type. Must be one of the value from the ColumnTypes class.
+     */
+    type?: ColumnType
+
+    /**
+     * Return type of HSTORE column.
+     * Returns value as string or as object.
+     */
+    hstoreType?: "object" | "string"
+
+    /**
+     * Query to be used to populate the column data. This query is used when generating the relational db script.
+     * The query function is called with the current entities alias either defined by the Entity Decorator or automatically
+     * @See https://typeorm.io/decorator-reference#virtualcolumn for more details.
+     */
+    query: (alias: string) => string
+
+    /**
+     * Specifies a value transformer(s) that is to be used to unmarshal
+     * this column when reading from the database.
+     */
+    transformer?: ValueTransformer | ValueTransformer[]
+}
diff --git a/src/driver/aurora-mysql/AuroraMysqlDriver.ts b/src/driver/aurora-mysql/AuroraMysqlDriver.ts
@@ -633,6 +633,9 @@ export class AuroraMysqlDriver implements Driver {
         ) {
             // convert to number if that exists in possible enum options
             value = parseInt(value)
+        } else if (columnMetadata.type === Number) {
+            // convert to number if number
+            value = !isNaN(+value) ? parseInt(value) : value
         }
 
         if (columnMetadata.transformer)

diff --git a/src/driver/mysql/MysqlDriver.ts b/src/driver/mysql/MysqlDriver.ts
@@ -634,6 +634,9 @@ export class MysqlDriver implements Driver {
             return "" + value
         } else if (columnMetadata.type === "set") {
             return DateUtils.simpleArrayToString(value)
+        } else if (columnMetadata.type === Number) {
+            // convert to number if number
+            value = !isNaN(+value) ? parseInt(value) : value
         }
 
         return value
@@ -683,6 +686,9 @@ export class MysqlDriver implements Driver {
             value = parseInt(value)
         } else if (columnMetadata.type === "set") {
             value = DateUtils.stringToSimpleArray(value)
+        } else if (columnMetadata.type === Number) {
+            // convert to number if number
+            value = !isNaN(+value) ? parseInt(value) : value
         }
 
         if (columnMetadata.transformer)

diff --git a/src/driver/oracle/OracleDriver.ts b/src/driver/oracle/OracleDriver.ts
@@ -545,6 +545,9 @@ export class OracleDriver implements Driver {
             value = DateUtils.stringToSimpleArray(value)
         } else if (columnMetadata.type === "simple-json") {
             value = DateUtils.stringToSimpleJson(value)
+        } else if (columnMetadata.type === Number) {
+            // convert to number if number
+            value = !isNaN(+value) ? parseInt(value) : value
         }
 
         if (columnMetadata.transformer)

diff --git a/src/driver/postgres/PostgresDriver.ts b/src/driver/postgres/PostgresDriver.ts
@@ -801,6 +801,9 @@ export class PostgresDriver implements Driver {
                         ? parseInt(value)
                         : value
             }
+        } else if (columnMetadata.type === Number) {
+            // convert to number if number
+            value = !isNaN(+value) ? parseInt(value) : value
         }
 
         if (columnMetadata.transformer)

diff --git a/src/driver/sap/SapDriver.ts b/src/driver/sap/SapDriver.ts
@@ -527,6 +527,9 @@ export class SapDriver implements Driver {
             value = DateUtils.stringToSimpleJson(value)
         } else if (columnMetadata.type === "simple-enum") {
             value = DateUtils.stringToSimpleEnum(value, columnMetadata)
+        } else if (columnMetadata.type === Number) {
+            // convert to number if number
+            value = !isNaN(+value) ? parseInt(value) : value
         }
 
         if (columnMetadata.transformer)

diff --git a/src/driver/spanner/SpannerDriver.ts b/src/driver/spanner/SpannerDriver.ts
@@ -439,6 +439,9 @@ export class SpannerDriver implements Driver {
             value = DateUtils.mixedDateToDateString(value)
         } else if (columnMetadata.type === "json") {
             value = typeof value === "string" ? JSON.parse(value) : value
+        } else if (columnMetadata.type === Number) {
+            // convert to number if number
+            value = !isNaN(+value) ? parseInt(value) : value
         }
 
         if (columnMetadata.transformer)

diff --git a/src/driver/sqlite-abstract/AbstractSqliteDriver.ts b/src/driver/sqlite-abstract/AbstractSqliteDriver.ts
@@ -410,6 +410,9 @@ export abstract class AbstractSqliteDriver implements Driver {
             value = DateUtils.stringToSimpleJson(value)
         } else if (columnMetadata.type === "simple-enum") {
             value = DateUtils.stringToSimpleEnum(value, columnMetadata)
+        } else if (columnMetadata.type === Number) {
+            // convert to number if number
+            value = !isNaN(+value) ? parseInt(value) : value
         }
 
         if (columnMetadata.transformer)

diff --git a/src/driver/sqlserver/SqlServerDriver.ts b/src/driver/sqlserver/SqlServerDriver.ts
@@ -568,6 +568,9 @@ export class SqlServerDriver implements Driver {
             value = DateUtils.stringToSimpleJson(value)
         } else if (columnMetadata.type === "simple-enum") {
             value = DateUtils.stringToSimpleEnum(value, columnMetadata)
+        } else if (columnMetadata.type === Number) {
+            // convert to number if number
+            value = !isNaN(+value) ? parseInt(value) : value
         }
 
         if (columnMetadata.transformer)

diff --git a/src/index.ts b/src/index.ts
@@ -22,6 +22,7 @@ export * from "./decorator/columns/PrimaryGeneratedColumn"
 export * from "./decorator/columns/PrimaryColumn"
 export * from "./decorator/columns/UpdateDateColumn"
 export * from "./decorator/columns/VersionColumn"
+export * from "./decorator/columns/VirtualColumn"
 export * from "./decorator/columns/ViewColumn"
 export * from "./decorator/columns/ObjectIdColumn"
 export * from "./decorator/listeners/AfterInsert"

diff --git a/src/metadata-args/types/ColumnMode.ts b/src/metadata-args/types/ColumnMode.ts
@@ -7,6 +7,7 @@
 export type ColumnMode =
     | "regular"
     | "virtual"
+    | "virtual-property"
     | "createDate"
     | "updateDate"
     | "deleteDate"

diff --git a/src/metadata-builder/EntityMetadataValidator.ts b/src/metadata-builder/EntityMetadataValidator.ts
@@ -123,29 +123,39 @@ export class EntityMetadataValidator {
         })
 
         if (!(driver.options.type === "mongodb")) {
-            entityMetadata.columns.forEach((column) => {
-                const normalizedColumn = driver.normalizeType(
-                    column,
-                ) as ColumnType
-                if (driver.supportedDataTypes.indexOf(normalizedColumn) === -1)
-                    throw new DataTypeNotSupportedError(
+            entityMetadata.columns
+                .filter((column) => !column.isVirtualProperty)
+                .forEach((column) => {
+                    const normalizedColumn = driver.normalizeType(
                         column,
-                        normalizedColumn,
-                        driver.options.type,
-                    )
-                if (
-                    column.length &&
-                    driver.withLengthColumnTypes.indexOf(normalizedColumn) ===
+                    ) as ColumnType
+                    if (
+                        driver.supportedDataTypes.indexOf(normalizedColumn) ===
                         -1
-                )
-                    throw new TypeORMError(
-                        `Column ${column.propertyName} of Entity ${entityMetadata.name} does not support length property.`,
                     )
-                if (column.type === "enum" && !column.enum && !column.enumName)
-                    throw new TypeORMError(
-                        `Column "${column.propertyName}" of Entity "${entityMetadata.name}" is defined as enum, but missing "enum" or "enumName" properties.`,
+                        throw new DataTypeNotSupportedError(
+                            column,
+                            normalizedColumn,
+                            driver.options.type,
+                        )
+                    if (
+                        column.length &&
+                        driver.withLengthColumnTypes.indexOf(
+                            normalizedColumn,
+                        ) === -1
                     )
-            })
+                        throw new TypeORMError(
+                            `Column ${column.propertyName} of Entity ${entityMetadata.name} does not support length property.`,
+                        )
+                    if (
+                        column.type === "enum" &&
+                        !column.enum &&
+                        !column.enumName
+                    )
+                        throw new TypeORMError(
+                            `Column "${column.propertyName}" of Entity "${entityMetadata.name}" is defined as enum, but missing "enum" or "enumName" properties.`,
+                        )
+                })
         }
 
         if (

diff --git a/src/metadata/ColumnMetadata.ts b/src/metadata/ColumnMetadata.ts
@@ -10,6 +10,7 @@ import { ValueTransformer } from "../decorator/options/ValueTransformer"
 import { ApplyValueTransformers } from "../util/ApplyValueTransformers"
 import { ObjectUtils } from "../util/ObjectUtils"
 import { InstanceChecker } from "../util/InstanceChecker"
+import { VirtualColumnOptions } from "../decorator/options/VirtualColumnOptions"
 
 /**
  * This metadata contains all information about entity's column.
@@ -238,6 +239,20 @@ export class ColumnMetadata {
      */
     isVirtual: boolean = false
 
+    /**
+     * Indicates if column is a virtual property. Virtual properties are not mapped to the entity.
+     * This property is used in tandem the virtual column decorator.
+     * @See https://typeorm.io/decorator-reference#virtualcolumn for more details.
+     */
+    isVirtualProperty: boolean = false
+
+    /**
+     * Query to be used to populate the column data. This query is used when generating the relational db script.
+     * The query function is called with the current entities alias either defined by the Entity Decorator or automatically
+     * @See https://typeorm.io/decorator-reference#virtualcolumn for more details.
+     */
+    query?: (alias: string) => string
+
     /**
      * Indicates if column is discriminator. Discriminator columns are not mapped to the entity.
      */
@@ -448,6 +463,7 @@ export class ColumnMetadata {
         if (options.args.options.array)
             this.isArray = options.args.options.array
         if (options.args.mode) {
+            this.isVirtualProperty = options.args.mode === "virtual-property"
             this.isVirtual = options.args.mode === "virtual"
             this.isTreeLevel = options.args.mode === "treeLevel"
             this.isCreateDate = options.args.mode === "createDate"
@@ -456,12 +472,18 @@ export class ColumnMetadata {
             this.isVersion = options.args.mode === "version"
             this.isObjectId = options.args.mode === "objectId"
         }
+        if (this.isVirtualProperty) {
+            this.isInsert = false
+            this.isUpdate = false
+        }
         if (options.args.options.transformer)
             this.transformer = options.args.options.transformer
         if (options.args.options.spatialFeatureType)
             this.spatialFeatureType = options.args.options.spatialFeatureType
         if (options.args.options.srid !== undefined)
             this.srid = options.args.options.srid
+        if ((options.args.options as VirtualColumnOptions).query)
+            this.query = (options.args.options as VirtualColumnOptions).query
         if (this.isTreeLevel)
             this.type = options.connection.driver.mappedDataTypes.treeLevel
         if (this.isCreateDate) {