From 8e0d8179ee1c9a7cbd1d6e04f1e8282c75815e19 Mon Sep 17 00:00:00 2001
From: Bradley Odell <btodell@hotmail.com>
Date: Fri, 15 May 2020 02:53:22 -0700
Subject: [PATCH] fix: use an empty string enum as the type of a primary key
 column (#6063)

Closes: #3874
---
 .../RawSqlResultsToEntityTransformer.ts       |  1 -
 test/github-issues/3874/entity/Settings.ts    | 16 ++++++++++
 test/github-issues/3874/issue-3874.ts         | 30 +++++++++++++++++++
 3 files changed, 46 insertions(+), 1 deletion(-)
 create mode 100644 test/github-issues/3874/entity/Settings.ts
 create mode 100644 test/github-issues/3874/issue-3874.ts

diff --git a/src/query-builder/transformer/RawSqlResultsToEntityTransformer.ts b/src/query-builder/transformer/RawSqlResultsToEntityTransformer.ts
index c1d0d670c0..c10e46facd 100644
--- a/src/query-builder/transformer/RawSqlResultsToEntityTransformer.ts
+++ b/src/query-builder/transformer/RawSqlResultsToEntityTransformer.ts
@@ -72,7 +72,6 @@ export class RawSqlResultsToEntityTransformer {
 
                 return keyValue;
             }).join("_"); // todo: check partial
-            if (!id) return;
 
             const items = map.get(id);
             if (!items) {
diff --git a/test/github-issues/3874/entity/Settings.ts b/test/github-issues/3874/entity/Settings.ts
new file mode 100644
index 0000000000..2d3cdc0866
--- /dev/null
+++ b/test/github-issues/3874/entity/Settings.ts
@@ -0,0 +1,16 @@
+import {Entity, Column, PrimaryColumn} from "../../../../src";
+
+enum Singleton {
+    EMPTY = ""
+}
+
+@Entity()
+export class Settings {
+
+    @PrimaryColumn()
+    readonly singleton: Singleton = Singleton.EMPTY;
+
+    @Column()
+    value!: string;
+
+}
diff --git a/test/github-issues/3874/issue-3874.ts b/test/github-issues/3874/issue-3874.ts
new file mode 100644
index 0000000000..4aa095de4f
--- /dev/null
+++ b/test/github-issues/3874/issue-3874.ts
@@ -0,0 +1,30 @@
+import "reflect-metadata";
+import {createTestingConnections, closeTestingConnections, reloadTestingDatabases} from "../../utils/test-utils";
+import {Connection} from "../../../src/connection/Connection";
+import {Settings} from "./entity/Settings";
+import {expect} from "chai";
+
+describe("github issues > #3874 Using an (empty string) enum as the type of a primary key column", () => {
+
+    let connections: Connection[];
+    before(async () => connections = await createTestingConnections({
+        entities: [Settings],
+        enabledDrivers: ["mysql", "mariadb"],
+        schemaCreate: true,
+        dropSchema: true,
+    }));
+    beforeEach(() => reloadTestingDatabases(connections));
+    after(() => closeTestingConnections(connections));
+
+    it("should reload entity", () => Promise.all(connections.map(async connection => {
+        // Create initial settings row
+        const newSettings = new Settings();
+        newSettings.value = "string";
+        await connection.manager.save(newSettings);
+        // Attempt to read settings back
+        const foundSettings = await connection.manager.findOne(Settings);
+        expect(foundSettings).to.be.an.instanceOf(Settings);
+        expect(foundSettings != null ? foundSettings.value : null).to.equal("string");
+    })));
+
+});