fix: empty objects being hydrated when eager loading relations that h…

…ave a `@VirtualColumn`

src/query-builder/SelectQueryBuilder.ts

@@ -2882,11 +2882,6 @@ export class SelectQueryBuilder<Entity extends ObjectLiteral>
                     })
                 })
             } else {
-                if (column.isVirtualProperty) {
-                    // Do not add unselected virtual properties to final select
-                    return
-                }
-
                 finalSelects.push({
                     selection: selectionPath,
                     aliasName: DriverUtils.buildAlias(

src/query-builder/transformer/RawSqlResultsToEntityTransformer.ts

@@ -247,7 +247,7 @@ export class RawSqlResultsToEntityTransformer {
                 entity,
                 this.driver.prepareHydratedValue(value, column),
             )
-            if (value !== null)
+            if (value !== null && !column.isVirtualProperty)
                 // we don't mark it as has data because if we will have all nulls in our object - we don't need such object
                 hasData = true
         })

test/github-issues/10431/entity/Category.ts

@@ -14,7 +14,7 @@ export class Category {
 
     @VirtualColumn({
         query: (alias) =>
-            `SELECT COUNT(*) FROM category WHERE id = ${alias}.id`,
+            `SELECT COUNT(*) FROM "category" WHERE "id" = ${alias}."id"`,
     })
     randomVirtualColumn: number
 

test/github-issues/10431/issue-10431.ts

@@ -8,33 +8,51 @@ import { DataSource } from "../../../src"
 import { expect } from "chai"
 
 import { Category, Product } from "./entity"
+import { DriverUtils } from "../../../src/driver/DriverUtils"
 
 describe("github issues > #10431 When requesting nested relations on foreign key primary entities, relation becomes empty entity rather than null", () => {
     let connections: DataSource[]
-    before(
-        async () =>
-            (connections = await createTestingConnections({
-                entities: [Category, Product],
-                schemaCreate: true,
-                dropSchema: true,
-            })),
-    )
+
+    before(async () => {
+        connections = await createTestingConnections({
+            entities: [Category, Product],
+            schemaCreate: true,
+            dropSchema: true,
+        })
+    })
     beforeEach(() => reloadTestingDatabases(connections))
     after(() => closeTestingConnections(connections))
 
     it("should return [] when requested nested relations are empty on ManyToMany relation with @VirtualColumn definitions", () =>
         Promise.all(
             connections.map(async (connection) => {
+                // By default, MySQL uses backticks instead of quotes for identifiers
+                if (DriverUtils.isMySQLFamily(connection.driver)) {
+                    const randomVirtualColumnMetadata = connection
+                        .getMetadata(Category)
+                        .columns.find(
+                            (columnMetadata) =>
+                                columnMetadata.propertyName ===
+                                "randomVirtualColumn",
+                        )!
+
+                    randomVirtualColumnMetadata.query = (alias) =>
+                        `SELECT COUNT(*) FROM \`category\` WHERE \`id\` = ${alias}.\`id\``
+                }
+
                 const productRepo = connection.getRepository(Product)
                 const testProduct = new Product()
                 testProduct.name = "foo"
+
                 await productRepo.save(testProduct)
+
                 const foundProduct = await productRepo.findOne({
                     where: {
                         id: testProduct.id,
                     },
                     relations: { categories: true },
                 })
+
                 expect(foundProduct?.name).eq("foo")
                 expect(foundProduct?.categories).eql([])
             }),