fix: .synchronize() drops json column on mariadb (#5391)

* #3636 synchronize drops json column on mariadb

* fixes failing test - QueryFailedError: ER_BLOB_CANT_HAVE_DEFAULT: BLOB/TEXT column 'data' can't have a default value

* simple commit to trigger ci jobs

src/driver/mysql/MysqlDriver.ts

@@ -537,6 +537,15 @@ export class MysqlDriver implements Driver {
         } else if (column.type === "uuid") {
             return "varchar";
 
+        } else if (column.type === "json" && this.options.type === "mariadb") {
+            /*
+             * MariaDB implements this as a LONGTEXT rather, as the JSON data type contradicts the SQL standard,
+             * and MariaDB's benchmarks indicate that performance is at least equivalent.
+             *
+             * @see https://mariadb.com/kb/en/json-data-type/
+             */
+            return "longtext";
+
         } else if (column.type === "simple-array" || column.type === "simple-json") {
             return "text";
 

test/github-issues/3636/entity/Post.ts

@@ -0,0 +1,16 @@
+import {Column} from "../../../../src/decorator/columns/Column";
+import {PrimaryColumn} from "../../../../src/decorator/columns/PrimaryColumn";
+import {Entity} from "../../../../src/decorator/entity/Entity";
+
+@Entity()
+export class Post {
+
+    @PrimaryColumn()
+    id: number;
+
+    @Column({
+        type: "json",
+    })
+    data: any;
+
+}

test/github-issues/3636/issue-3636.ts

@@ -0,0 +1,33 @@
+import "reflect-metadata";
+import {closeTestingConnections, createTestingConnections, reloadTestingDatabases} from "../../utils/test-utils";
+import {Connection} from "../../../src/connection/Connection";
+import {Post} from "./entity/Post";
+import {expect} from "chai";
+
+describe("github issues > #3636 synchronize drops (and then re-adds) json column in mariadb", () => {
+
+    let connections: Connection[];
+    before(async () => connections = await createTestingConnections({
+        entities: [__dirname + "/entity/*{.js,.ts}"],
+        subscribers: [__dirname + "/subscriber/*{.js,.ts}"],
+        enabledDrivers: ["mariadb"],
+    }));
+    beforeEach(() => reloadTestingDatabases(connections));
+    after(() => closeTestingConnections(connections));
+
+    it("should not drop json column", () => Promise.all(connections.map(async function(connection) {
+
+        const post = new Post();
+        post.id = 1;
+        post.data = {hello: "world"};
+        await connection.manager.save(post);
+
+        await connection.synchronize();
+
+        const loadedPost = await connection.manager.findOne(Post, 1);
+
+        expect(loadedPost).to.be.not.empty;
+        expect(loadedPost!.data.hello).to.be.eq("world");
+    })));
+
+});