XPath Editor

Overview

The XPath Editor provides a powerful way to create complex data transformations beyond simple field-to-field mappings. While drag-and-drop is great for basic mappings, the XPath Editor lets you combine fields, apply functions, perform calculations, and implement sophisticated business logic.

When to use the XPath Editor:

• Combining multiple source fields into one target field
• Applying string manipulation (concatenation, substring, case conversion)
• Performing mathematical calculations
• Using conditional expressions within a single mapping
• Applying XPath functions for date formatting, number formatting, and more

Opening the XPath Editor

To edit or create complex XPath expressions, click the pencil icon on any target field that has a mapping. This opens the XPath Editor where you can build your expression.

Building XPath Expressions

The XPath Editor interface provides two main areas: a palette on the left with fields and functions, and an expression editor on the right.

Adding Fields

You can add source fields to your expression by:

• Typing directly - Enter field paths manually using XPath syntax
• Drag and drop - Drag fields from the Fields tab and drop them into the editor

Using XPath Functions

The XPath Editor provides access to a comprehensive library of functions for data transformation:

String Functions:

• concat() - Combine multiple strings
• substring() - Extract part of a string
• upper-case(), lower-case() - Change text case
• normalize-space() - Remove extra whitespace

Numeric Functions:

• sum(), avg(), min(), max() - Aggregate calculations
• round(), floor(), ceiling() - Number rounding
• format-number() - Number formatting

Date/Time Functions:

• current-date(), current-time() - Get current date/time
• format-date(), format-time() - Format date/time values

Conditional Functions:

• if() - Inline conditional logic
• choose() - Multi-branch conditionals

To use functions:

1. Switch to the Functions tab in the left palette

   

   

2. Drag the function you need and drop it into the editor

   

   

3. Fill in the function parameters with field references or literal values

Saving Your Expression

Once you’ve built your XPath expression, click the Close button to apply it to the mapping.

The mapping will now appear in the tree view with your custom XPath expression.

Next Steps

You’ve now learned all the core DataMapper features! You can:

• Create simple and complex mappings between XML and JSON data
• Use conditional logic with if, choose-when-otherwise, and for-each
• Build advanced transformations with XPath functions
• Manage your schemas, parameters, and mappings

For more information, visit the Kaoto documentation.