DataWeave Examples

The following DataWeave examples demonstrate common data extraction and transformation approaches. There are DataWeave code examples of how to transform data, and also examples of Mule applications that implement DataWeave transformations. Before you begin, note that 2.x versions of DataWeave are used by Mule 4 apps. For DataWeave in Mule 3 apps, refer to DataWeave version 1.2 examples. For other DataWeave versions, you can use the version selector in the DataWeave table of contents.

DataWeave Code Examples

These examples show how to use standalone DataWeave to extract and transform data.

Example Description

Extract Data

Shows common selector expressions for extracting values from a data source, such as a Mule message.

Select XML Elements

Uses a single-value DataWeave selector (.) to extract data from XML elements.

Set a Default Value

Shows some common ways to set default values.

Set Reader and Writer Configuration Properties

Shows how to use and change the settings for reading and writing data formats, such as application/csv.

Transform XML to JSON

Uses selectors to perform a basic format transformation. It does not use any functions.

Map Data

Uses map to reorganize fields in a JSON array. It uses as to coerce a String into a Number.

Map and Flatten an Array

Uses flatMap to map objects in an array and flatten the resulting array.

Map Objects

Uses mapObject to go through the keys and values in each object, and set all the keys to upper case.

Map Objects Key

Uses the mapObject function to iterate through an array of objects and appends a new object that matches the value of the specified criteria.

Map the Objects within an Array

Uses the multi-value selector to pick out the keys in an object that are named "book", these are returned as an array. It then uses map to iterate through the array this creates.

Dynamic Map Based on a Definition

Transforms the payload according to definitions sent in a variable. It defines a function that applies the logic defined in the variable, using map and default.

Rename Keys

Renames some keys in a JSON object while retaining the names of all other keys in the output. Uses mapObject, if, as, and and.

Output a Field When Present

Uses if with map to determine whether to include a field in the output. You might use it to exclude fields that contain sensitive data.

Format According to Type

Uses mapObject to apply changes to the keys in an object, depending on the type of their corresponding values. Uses camelize, capitalize, and pluralize depending on the if and else if statement.

Regroup Fields

Uses groupBy, mapObject, and map to reorganize JSON and XML fields.

Zip Arrays Together

Uses zip to rearrange pairs of similar arrays so that they form a series of touples with the matching values from each.

Pick Top Elements

Uses groupBy and map to sort a list of candidates according to their score at a test, then it splits the array to select only the top candidates.

Change the Value of a Field

Masks sensitive data by changing values of some keys to asterisks (****`). Uses mapObject, if, and else.

Exclude Fields from the Output

Shows how to exclude unwanted elements from the output. Uses the - (remove) and mapObject functions.

Use Constant Directives

Defines a series of constant strings and numbers in the header, these are used to filter input and to concatenate into URLs. Uses map, if and ++ to concatenate strings.

Define a Custom Addition Function

Defines a function that obtains totals and subtotals through the accumulator function. Also performs additions, subtractions, and multiplications of numeric values.

Define a Function That Flattens Data in a List

Uses reduce, map, if, and splitBy to modify and conditionally output fields from a list.

Flatten Elements of Arrays

Uses flatten, the object constructor braces ({}), and selectors to flatten subarrays and nested elements in arrays. Uses concatenation (++) to combine arrays before flattening them and uses the ..* descendants selector on a key to select values from a flattened list.

Use Regular Expressions

Shows uses of regular expressions in arguments to several DataWeave functions.

Output Self-closing XML Tags

Uses inlineCloseOn="empty" to close empty tags (for example, <element2/>).

Insert an Attribute into an XML Tag

Uses the @(key:value) syntax to create an XML attribute.

Remove Specified XML Attributes

Defines a function that recursively checks an element and all of its children for a specific XML attribute and removes it with -. It also uses mapObject, if and is (to match types).

Pass XML Attributes

Pass XML attributes from the input source payload to the output XML. It uses the dynamic attribute expression @dynamicAttributes to create the attributes of the new output tag by selecting the attributes dynamically from the input.

Include XML Namespaces

Defines multiple XML namespaces and references these in each tag.

Remove Objects Containing Specified Key-Value Pairs

Removes all objects that contain a set of key-value pairs from an array of objects. Uses filter with contains and a not operator.

Reference Multiple Inputs

References data on the payload, a message attribute and a variable. It then processes these through map, filter and multiplications.

Merge Fields from Separate Objects

Reference data that arrives in multiple separate payloads from one single Mule event. Filters the output based on a unique identifier. Uses map, using, as, and filter functions.

Parse Dates

Defines a function that normalizes conflicting date formats into a single, common format. Uses mapObject, replace and as to coerce a data type.

Add and Subtract Dates

Performs multiple math operations combining different types related to date and time.

Change a Time Zone

Uses >> with a time zone ID to change a time zone and provides a list of available time zone IDs.

Format Dates and Times

Uses formatting characters such as uuuu/MM/dd to change the format of dates and times. Creates a date-time format using a custom DataWeave type.

Work with Multipart Data

Uses mapObject to iterate over a multipart payload and extract data from each part. It also uses read with a boundary value to read the multipart content.

Conditionally Reduce a List through a Function

Defines a function that reduces a list of elements into one field. It then calls this function only when a certain field has values. Uses map, reduce, splitBy, if and ++ to append to an array.

Pass Functions as Arguments

Defines a function that expects to receive two inputs: a function to apply and an element to apply it on. The function is also recursively applied to the element’s children. It uses mapObject lower is if/else.

DataWeave Code in MuleSoft Applications Examples

These examples show how to use DataWeave to extract and transform data in MuleSoft applications.

Example Description

Change a Script’s Output Mime Type

Shows how to customize the MIME type of a given format output, including an example of a JSON output with application/problem+json MIME type.

Look Up Data in an Excel (XLSX) File

Uses filter to return rows that contain a specified value.

Look Up Data in CSV File

Uses filter with map to look up data in a CSV file and return a country code for each calling code found within an input array of phone numbers.

Decode and Encode Base64

Converts a file stream into Base64 and converts a Base64 string into a file stream. Uses a PDF file as the input and output.

Call Java Methods with DataWeave

Calls Java methods from a Java class in a Mule project.

Read and Write a Flat File

Use DataWeave to read and write flat files in a Mule application.

Use a Reader Property through a Connector

Use a reader property through a Connector operation.

Use a Mule Variable as a Configuration Value

Use a Mule variable as a configuration value.

Extract Key/Value Pairs with Pluck Function

Use the DataWeave pluck function to extract key-value pairs from a JSON payload and store them into Mule event variables.

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