Render Strategy Implementations

New in v0.3.0

MSR uses the Strategy Pattern to provide multiple output formats for migration information, from beautiful terminal tables to structured JSON for CI/CD integration.

Available Render Strategies

AsciiTableRenderStrategy

The default rendering strategy that outputs formatted ASCII tables to the terminal. Provides a rich, visual display with human-readable timestamps, color-coded warnings, and alignment.

Best for: Local development, manual migration runs, interactive CLI tools

JsonRenderStrategy

Outputs migration information as structured JSON. Supports both pretty-printed (indented) and compact formats. Perfect for parsing by CI/CD tools, log aggregators, and monitoring systems.

Best for: CI/CD pipelines, log aggregation, automated tools, programmatic parsing

SilentRenderStrategy

Suppresses all rendering output completely. Ideal for testing, library usage, and scenarios where visual output is not desired.

Best for: Unit tests, library integration, headless environments, silent operations

Strategy Comparison

Choose the right render strategy for your environment:

Strategy Format Human Readable Machine Parsable Best For
AsciiTable 📊 Tables 🟢 Excellent 🔴 Poor Development
Json 📋 JSON 🟡 Moderate 🟢 Excellent CI/CD
Silent ❌ None N/A N/A Testing

Feature Matrix

Feature AsciiTable Json Silent
Output Format ASCII Tables JSON None
Human Readable ✅ Very ⚠️ Structured N/A
Machine Parsable ❌ ✅ N/A
Pretty Printing ✅ ✅ Configurable N/A
Compact Mode ❌ ✅ N/A
Color Support ✅ ❌ N/A
File Size 💾 Large 💾 Small Zero
CI/CD Friendly ❌ ✅ ✅

Recommended: Use AsciiTableRenderStrategy for local development and JsonRenderStrategy in CI/CD pipelines for easy parsing.

Usage

Basic Usage 

import {
    MigrationScriptExecutor,
    AsciiTableRenderStrategy,
    JsonRenderStrategy,
    SilentRenderStrategy
} from '@migration-script-runner/core';

// Default ASCII tables (no configuration needed)
const config = new Config();
const executor = new MigrationScriptExecutor({ handler }, config);

// Pretty JSON for readability
const executor = new MigrationScriptExecutor({ handler, 
    renderStrategy: new JsonRenderStrategy(true)
});

// Compact JSON for log aggregation
const executor = new MigrationScriptExecutor({ handler, 
    renderStrategy: new JsonRenderStrategy(false)
});

// Silent for testing
const executor = new MigrationScriptExecutor({ handler, 
    renderStrategy: new SilentRenderStrategy()
});

With Custom Loggers

Render strategies work seamlessly with custom loggers:

import { FileLogger, JsonRenderStrategy } from '@migration-script-runner/core';

const logger = new FileLogger({ logPath: './migrations.log' });
const executor = new MigrationScriptExecutor({ handler, 
    logger,
    renderStrategy: new JsonRenderStrategy(true)
});

Creating Custom Render Strategies

All render strategies implement the IRenderStrategy interface. See the Custom Rendering Guide for detailed examples of creating your own render strategy implementations.

Next Steps

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