revert_migration

Revert a specific migration file in PocketBase databases to undo schema changes. Specify the migration file name to execute the rollback process.

Instructions

Revert a specific migration file.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`migrationFile`	Yes	Name of the migration file to revert.

Implementation Reference

src/tools/migration-tools.ts:284-297 (handler)

Handler for the 'revert_migration' MCP tool. Validates input parameters and delegates to the core revertMigration function.

async function handleRevertMigration(args: RevertMigrationArgs, pb: PocketBase): Promise<ToolResult> {
    if (!args.migrationFile) {
        throw invalidParamsError("Missing required argument: migrationFile");
    }
    
    try {
        const result = await revertMigration(args.migrationFile, pb);
        return {
            content: [{ type: 'text', text: result }],
        };
    } catch (error: any) {
        throw new Error(`Failed to revert migration: ${error.message}`);
    }
}

src/tools/migration-tools.ts:134-143 (registration)

Registration of the 'revert_migration' tool in the list of migration tools, including its name, description, and JSON schema for input validation.

    name: 'revert_migration',
    description: 'Revert a specific migration file.',
    inputSchema: {
        type: 'object',
        properties: {
            migrationFile: { type: 'string', description: 'Name of the migration file to revert.' },
        },
        required: ['migrationFile'],
    },
},

src/tools/migration-tools.ts:42-44 (schema)
TypeScript interface defining the input arguments for the revert_migration handler.
```
interface RevertMigrationArgs {
    migrationFile: string;
}
```

src/migrations/execution.ts:86-108 (helper)

Core helper function implementing the migration revert logic: loads the JS migration file and executes its down() migration.

export async function revertMigration(
    migrationFile: string, 
    pb: PocketBase, 
    migrationsDir: string
): Promise<string> {
    try {
        const migrationPath = path.join(migrationsDir, migrationFile);
        
        // Check if file exists
        await fs.access(migrationPath, fs.constants.R_OK);
        
        // Load the migration
        const migration = await loadMigrationFile(migrationPath);
        
        // Execute the down function
        await migration.down(pb);
        
        return `Successfully reverted migration: ${migrationFile}`;
    } catch (error: any) {
        console.error(`Error reverting migration ${migrationFile}:`, error);
        throw new Error(`Failed to revert migration: ${error.message}`);
    }
}

src/migrations/execution.ts:19-46 (helper)

Supporting helper that parses a PocketBase migration JS file to extract and instantiate the up/down functions using regex and new Function.

async function loadMigrationFile(migrationPath: string): Promise<MigrationFunctions> {
    try {
        // Read the file content
        const content = await fs.readFile(migrationPath, 'utf-8');
        
        // Extract the up and down functions using regex
        const migrateMatch = content.match(/migrate\(\s*\(\s*app\s*\)\s*=>\s*\{([\s\S]*?)}\s*,\s*\(\s*app\s*\)\s*=>\s*\{([\s\S]*?)}\s*\)/);
        
        if (!migrateMatch || migrateMatch.length < 3) {
            throw new Error(`Invalid migration format in file: ${migrationPath}`);
        }
        
        const upBody = migrateMatch[1].trim();
        const downBody = migrateMatch[2].trim();
        
        // Create the up and down functions
        const up = new Function('app', `${upBody}`);
        const down = new Function('app', `${downBody}`);
        
        return {
            up: async (app: any) => await up(app),
            down: async (app: any) => await down(app)
        };
    } catch (error: any) {
        console.error(`Error loading migration file ${migrationPath}:`, error);
        throw new Error(`Failed to load migration file: ${error.message}`);
    }
}

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