fix: prevent transactions in the Cordova driver (typeorm#7771)

the cordova driver silently ignores all attempts to begin
or commit transactions.  this leads to data loss and invalid
operations occurring when developers expect transactions to work
and then they are silently ignored

src/driver/cordova/CordovaQueryRunner.ts

@@ -9,12 +9,12 @@ import {Broadcaster} from "../../subscriber/Broadcaster";
  * Runs queries on a single sqlite database connection.
  */
 export class CordovaQueryRunner extends AbstractSqliteQueryRunner {
-    
+
     /**
      * Database driver used by connection.
      */
     driver: CordovaDriver;
-    
+
     // -------------------------------------------------------------------------
     // Constructor
     // -------------------------------------------------------------------------
@@ -54,7 +54,7 @@ export class CordovaQueryRunner extends AbstractSqliteQueryRunner {
                     for (let i = 0; i < result.rows.length; i++) {
                         resultSet.push(result.rows.item(i));
                     }
-                    
+
                     ok(resultSet);
                 }
             }, (err: any) => {
@@ -98,6 +98,48 @@ export class CordovaQueryRunner extends AbstractSqliteQueryRunner {
         });
     }*/
 
+    /**
+     * Would start a transaction but this driver does not support transactions.
+     */
+    async startTransaction(): Promise<void> {
+        throw new Error('Transactions are not supported by the Cordova driver')
+    }
+
+    /**
+     * Would start a transaction but this driver does not support transactions.
+     */
+    async commitTransaction(): Promise<void> {
+        throw new Error('Transactions are not supported by the Cordova driver')
+    }
+
+    /**
+     * Would start a transaction but this driver does not support transactions.
+     */
+    async rollbackTransaction(): Promise<void> {
+        throw new Error('Transactions are not supported by the Cordova driver')
+    }
+
+    /**
+     * Removes all tables from the currently connected database.
+     * Be careful with using this method and avoid using it in production or migrations
+     * (because it can clear all your database).
+     */
+    async clearDatabase(): Promise<void> {
+        await this.query(`PRAGMA foreign_keys = OFF;`);
+        try {
+            const selectViewDropsQuery = `SELECT 'DROP VIEW "' || name || '";' as query FROM "sqlite_master" WHERE "type" = 'view'`;
+            const dropViewQueries: ObjectLiteral[] = await this.query(selectViewDropsQuery);
+
+            const selectTableDropsQuery = `SELECT 'DROP TABLE "' || name || '";' as query FROM "sqlite_master" WHERE "type" = 'table' AND "name" != 'sqlite_sequence'`;
+            const dropTableQueries: ObjectLiteral[] = await this.query(selectTableDropsQuery);
+
+            await Promise.all(dropViewQueries.map(q => this.query(q["query"])));
+            await Promise.all(dropTableQueries.map(q => this.query(q["query"])));
+        } finally {
+            await this.query(`PRAGMA foreign_keys = ON;`);
+        }
+    }
+
     // -------------------------------------------------------------------------
     // Protected Methods
     // -------------------------------------------------------------------------
@@ -108,4 +150,4 @@ export class CordovaQueryRunner extends AbstractSqliteQueryRunner {
     protected parametrize(objectLiteral: ObjectLiteral, startIndex: number = 0): string[] {
         return Object.keys(objectLiteral).map((key, index) => `"${key}"` + "=?");
     }
-}
+}

src/schema-builder/RdbmsSchemaBuilder.ts

@@ -67,8 +67,15 @@ export class RdbmsSchemaBuilder implements SchemaBuilder {
         this.queryRunner = this.connection.createQueryRunner();
         // CockroachDB implements asynchronous schema sync operations which can not been executed in transaction.
         // E.g. if you try to DROP column and ADD it again in the same transaction, crdb throws error.
-        if (!(this.connection.driver instanceof CockroachDriver))
+        const isUsingTransactions = (
+            !(this.connection.driver instanceof CockroachDriver) &&
+            this.connection.options.migrationsTransactionMode !== "none"
+        );
+
+        if (isUsingTransactions) {
             await this.queryRunner.startTransaction();
+        }
+
         try {
             const tablePaths = this.entityToSyncMetadatas.map(metadata => metadata.tablePath);
             // TODO: typeorm_metadata table needs only for Views for now.
@@ -83,14 +90,16 @@ export class RdbmsSchemaBuilder implements SchemaBuilder {
             if (this.connection.queryResultCache)
                 await this.connection.queryResultCache.synchronize(this.queryRunner);
 
-            if (!(this.connection.driver instanceof CockroachDriver))
+            if (isUsingTransactions) {
                 await this.queryRunner.commitTransaction();
+            }
 
         } catch (error) {
 
             try { // we throw original error even if rollback thrown an error
-                if (!(this.connection.driver instanceof CockroachDriver))
+                if (isUsingTransactions) {
                     await this.queryRunner.rollbackTransaction();
+                }
             } catch (rollbackError) { }
             throw error;