Thinking in Transformations
A transformation is easier to understand when you can account for every value it produces.
DataWeave in Depth
Learn the transformation language one step at a time: values and functions, collections and reports, then formats, dates and a tested order pipeline. Twenty-four chapters build from Hello World to a complete transformation, with advanced workshops in four appendices.
Download as an EPUB 29 chapters — read offline on any e-reader
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Your First DataWeave Script
Start with a script whose entire result you can see before running it.
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Read an Object and Build Another
The order header in chapter 1 was fixed in the source.
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Calculate with Values and Convert Deliberately
An order line gives us a price and a quantity.
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Make Decisions and Handle Missing Fields
The order service offers free delivery at a stated threshold.
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Give a Calculation a Function
The same multiplication now appears in several results.
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Transform Every Item with map
So far, each input has been one record.
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Select Lines and Calculate an Order Total
We can calculate an amount for every line.
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Sort, Select and Remove Duplicates
The report now contains lines from two orders.
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Work with Nested Collections
A report can preserve each order with its own lines, or flatten all the lines into one list.
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Transform Object Fields and Keys
So far, we have named output fields directly.
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Group Records into Reports
The category report needs a total for each group of lines.
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Enrich Records from a Lookup
An order knows which SKU was bought; the catalogue knows its current display name.
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Carry a Result through reduce
A sum gives us the final order amount.
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State Contracts and Branch on Input Shape
A helper used by several transformations needs a clear input contract.
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Share Helpers and Automate Their Checks
The line-total calculation is now useful in an order summary, a category report and an enriched report.
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Clean Text and Extract Patterns
A supplier label, a field name and a product code all arrive as strings, but each needs a different operation.
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Readers, Writers and the JSON Contract
The body builds model values.
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Read and Produce Reliable CSV
A CSV reader gives us an array of row objects, so the mapping techniques are familiar.
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Read and Write XML Orders
The order now arrives as XML.
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Handle XML Namespaces and Content
The basic XML order is working.
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Parse and Format Dates
A date-shaped string is still a string.
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Preserve Instants and Calculate Intervals
A date identifies a calendar day.
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Build and Verify the Order Report
The shipping partner sends a namespaced XML batch.
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Understand the Cost of a Transformation
The report works on a small batch.
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Appendix A: Runner and CLI Reference
Use this reference when a lesson needs another input binding, a module path or a command-line run.
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Appendix B: Functions as Values, in Depth
Read this workshop after the collection chapters.
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Appendix C: Additional Formats and Mule Integration
These independent workshops apply the reader/writer model to Java, fixed-width records, Excel and multipart, then place checks around a Mule flow.
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Appendix D: Library and Behavior Reference
This reference collects the detailed conversion, selection, scope and library investigations that are useful once you can follow the main examples.