Transform Builder

The Transform Builder is DataLensia's flagship tool for data engineering. It provides a sophisticated, desktop-class environment for performing complex Extract, Transform, Load (ETL) operations directly in your web browser. This tool allows you to visually map a source schema to a completely different target structure, apply powerful transformation chains, and export the results instantly. It uses drag-and-drop field mapping and a live preview experience to make even complex JSON migrations intuitive. Designed for developers, data analysts, and architects, the Transform Builder eliminates the need for writing repetitive boilerplate mapping code while maintaining 100% data privacy.

✨ Key Features

• Magic Map: Automatically discover and map every leaf field from your JSON source tree.
• Drag & Drop: Pull fields from your source tree directly into your target output.
• Live Preview: See how your transformations affect real data in real-time.
• Code Export: Generate the JavaScript logic required to run the transformation programmatically.
• Import/Export Configs: Save your mapping configurations as JSON files for reuse across projects.
• Fullscreen Mode: Work in a distraction-free environment.
• Collision Detection: Warns you when two source fields map to the same target key.

⛓️ Transformation Operations (25+)

Chain multiple operations together — they execute in sequence from left to right:

Text Operations

Operation	Description
Uppercase	Convert text to UPPERCASE
Lowercase	Convert text to lowercase
Trim	Remove leading/trailing whitespace
Concat	Prepend or append text to a value
Substring	Extract a portion of the text
Reverse String	Reverse character order
Snake Case	Convert to snake_case
Camel Case	Convert to camelCase
Pascal Case	Convert to PascalCase
Title Case	Convert to Title Case
Capitalize	Capitalize first letter
Replace	Simple string find and replace

Type Operations

Operation	Description
To Number	Cast value to a numeric type
To Boolean	Cast value to boolean

Value Operations

Operation	Description
Default Value	Set a fallback for null/undefined
UUID v4	Generate a random UUID

Advanced Operations

Operation	Description
Date Format	Format date strings or timestamps
Template	Use {{field}} references from the source record
Math	Apply math operations (round, floor, ceil, +, -, *, /)
Regex Replace	Search and replace using regular expressions
URL Encode	Encode a string for use in a URL
URL Decode	Decode a URL-encoded string
Base64 Encode	Encode a string to Base64
Base64 Decode	Decode a Base64 string
Hash	Generate a simple hash
Custom Script	Run custom JavaScript in a sandboxed environment
Conditional	If/Then/Else logic based on value conditions

🛠️ How to Use

1. Navigate to the Transform Builder.
2. Upload your source JSON or paste it into the editor.
3. Click Magic Map to auto-generate mappings, or drag fields manually.
4. For each mapping, optionally:
   • Rename the target key.
   • Add one or more transformation operations (click ⚡).
   • Reorder operations by dragging.
5. View the live preview in the right panel.
6. Export the transformed result as JSON, or download the mapping config.

Build a Pipeline

With valid source data and at least one mapping, choose Build workflow in the standalone Transform Builder. Apply raw JSON edits and fix mapping configuration errors first:

• Transform and inspect opens JSON or NDJSON Input → Transform → Table View.
• Transform and export opens JSON or NDJSON Input → Transform → JSON File Export.
• Transform and mock opens JSON or NDJSON Input → Transform → GET Mock Output. Edit the pipeline input or mappings and run it again to update the mock output; rerunning unchanged inputs and mappings produces the same data.

The temporary pipeline contains a copy of your current input and mappings, including mapping operations. Run it to inspect or use the transformed result, then edit its nodes as needed. Pipeline changes do not update the standalone Builder automatically. Use Save this pipeline to copy the temporary workflow into your saved standalone pipeline.

🔒 Script Sandbox

Custom scripts are executed in a restricted environment where dangerous globals (window, document, fetch, localStorage, etc.) are blocked. This prevents any unauthorized access from within transformations.

🗂️ Config Management

• Export Config: Download your current mappings as a reusable .json file.
• Import Config: Load a previously saved mapping configuration.
• Clear All: Reset all mappings to start fresh.

🧠 Advanced Field Mapping Techniques

For complex data migrations, the Transform Builder supports several advanced mapping strategies:

• Deep Nesting: Create deeply nested target structures by manually adding rows or using the "Nest" action on existing keys. This allows you to transform flat datasets into hierarchical formats required by modern APIs.
• Array Handling: Map source fields into array structures by dropping them onto target array items. The builder intelligently handles index-based mapping and preserves structural integrity.
• Conditional Mapping: Use the Conditional operator to apply different transformation logic based on the value of a source field. For example, you can format a phone number differently depending on the country code.
• Template-Based Concat: The Template operator allows you to build complex strings using multiple source fields (e.g., {{firstName}} {{lastName}}) without needing a long chain of Concat operations.

🚀 ETL Best Practices

To get the most out of the Transform Builder, consider these best practices:

1. Start with Magic Map: Always use the "Magic Map" feature first to discover all leaf fields in your source data. You can then prune and rename fields to fit your target schema.
2. Chain Operations Strategically: Remember that transformations are executed from left to right. For example, if you need to hash a value, make sure to "Trim" and "Lowercase" it first to ensure consistent hash results.
3. Use Default Values: Always provide a "Default Value" for critical fields to prevent your target JSON from having unexpected null or undefined values when source fields are missing.
4. Leverage the Sandbox: Use the "Custom Script" operator for logic that can't be achieved with built-in operators. Since it's sandboxed, you can safely write complex JavaScript snippets to handle edge cases.

🔄 Integration with External Workflows

The Transform Builder is designed to fit seamlessly into your existing development lifecycle:

• Programmatic Use: Once you've perfected your mapping, click the JS Code button to generate a standalone JavaScript function. You can paste this function directly into your Node.js or browser-based application to run the transformation at scale.
• Version Control: By exporting your mapping configuration as a JSON file, you can check it into your Git repository along with your project's source code, enabling team-wide collaboration on data transformation rules.
• GitHub Sync: Use DataLensia's built-in GitHub synchronization to automatically back up your workspace metadata, including all active transformation mappings, to a remote repository.

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🚀 Try it now

Build your first professional mapping in the Transform Builder.