From ad13069f137188dd23a2def2d998580d44a80ab5 Mon Sep 17 00:00:00 2001
From: Leonardo Falk <leonardo.falk@hotmail.com>
Date: Thu, 10 Oct 2019 15:23:27 -0300
Subject: [PATCH] feat: export Migration Execution API from main package (fixes
 #4880)

---
 src/index.ts                       |  2 +
 src/migration/MigrationExecutor.ts | 87 +++++++++++++++++++++++++++++-
 2 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/src/index.ts b/src/index.ts
index 71829638a7c..5fb9d8c44e6 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -139,6 +139,8 @@ export {DeleteResult} from "./query-builder/result/DeleteResult";
 export {QueryRunner} from "./query-runner/QueryRunner";
 export {EntityManager} from "./entity-manager/EntityManager";
 export {MongoEntityManager} from "./entity-manager/MongoEntityManager";
+export {Migration} from "./migration/Migration";
+export {MigrationExecutor} from "./migration/MigrationExecutor";
 export {MigrationInterface} from "./migration/MigrationInterface";
 export {DefaultNamingStrategy} from "./naming-strategy/DefaultNamingStrategy";
 export {NamingStrategyInterface} from "./naming-strategy/NamingStrategyInterface";
diff --git a/src/migration/MigrationExecutor.ts b/src/migration/MigrationExecutor.ts
index aef39b06705..bae2314b0a7 100644
--- a/src/migration/MigrationExecutor.ts
+++ b/src/migration/MigrationExecutor.ts
@@ -51,6 +51,78 @@ export class MigrationExecutor {
     // Public Methods
     // -------------------------------------------------------------------------
 
+    /**
+     * Tries to execute a single migration given.
+     */
+    public async executeMigration(migration: Migration): Promise<Migration> {
+        return this.withQueryRunner(async (queryRunner) => {
+            await this.createMigrationsTableIfNotExist(queryRunner);
+            await (migration.instance as any).up(queryRunner);
+            await this.insertExecutedMigration(queryRunner, migration);
+
+            return migration;
+        });
+    }
+
+    /**
+     * Returns an array of all migrations.
+     */
+    public async getAllMigrations(): Promise<Migration[]> {
+        return Promise.resolve(this.getMigrations());
+    }
+
+    /**
+     * Returns an array of all executed migrations.
+     */
+    public async getExecutedMigrations(): Promise<Migration[]> {
+        return this.withQueryRunner(async queryRunner => {
+            await this.createMigrationsTableIfNotExist(queryRunner);
+
+            return await this.loadExecutedMigrations(queryRunner);
+        });
+    }
+
+    /**
+     * Returns an array of all pending migrations.
+     */
+    public async getPendingMigrations(): Promise<Migration[]> {
+        const allMigrations = await this.getAllMigrations();
+        const executedMigrations = await this.getExecutedMigrations();
+
+        return allMigrations.filter(migration =>
+            executedMigrations.find(
+                executedMigration =>
+                    executedMigration.name === migration.name
+            )
+        );
+    }
+
+    /**
+     * Inserts an executed migration.
+     */
+    public insertMigration(migration: Migration): Promise<void> {
+        return new Promise((resolve, reject) => {
+            this.withQueryRunner(queryRunner => {
+                this.insertExecutedMigration(queryRunner, migration)
+                    .then(resolve)
+                    .catch(reject);
+            });
+        });
+    }
+
+    /**
+     * Deletes an executed migration.
+     */
+    public deleteMigration(migration: Migration): Promise<void> {
+        return new Promise((resolve, reject) => {
+            this.withQueryRunner(queryRunner => {
+                this.deleteExecutedMigration(queryRunner, migration)
+                    .then(resolve)
+                    .catch(reject);
+            });
+        });
+    }
+
     /**
      * Lists all migrations and whether they have been executed or not
      * returns true if there are unapplied migrations
@@ -333,8 +405,9 @@ export class MigrationExecutor {
         const migrations = this.connection.migrations.map(migration => {
             const migrationClassName = migration.name || (migration.constructor as any).name;
             const migrationTimestamp = parseInt(migrationClassName.substr(-13));
-            if (!migrationTimestamp)
+            if (!migrationTimestamp || isNaN(migrationTimestamp)) {
                 throw new Error(`${migrationClassName} migration name is wrong. Migration class name should have a JavaScript timestamp appended.`);
+            }
 
             return new Migration(undefined, migrationTimestamp, migrationClassName, migration);
         });
@@ -421,4 +494,16 @@ export class MigrationExecutor {
         }
 
     }
+
+    protected async withQueryRunner<T extends any>(callback: (queryRunner: QueryRunner) => T) {
+        const queryRunner = this.queryRunner || this.connection.createQueryRunner("master");
+
+        try {
+            return callback(queryRunner);
+        } finally {
+            if (!this.queryRunner) {
+                await queryRunner.release();
+            }
+        }
+    }
 }