coderz.py

DataWeave can read and write many types of data formats, such as JSON, XML, CSV, XSLS and many others. Before you begin, note that DataWeave version 2 is for Mule 4 apps.

DataWeave supports the following formats as input and output:

application/avro	avro	Avro Format
application/csv	csv	CSV Format
application/dw	dw	DataWeave Format (dw) for testing a DataWeave expression
application/flatfile	flatfile	Flat File Format, COBOL Copybook Format, Fixed Width Format
application/java	java	Java Format, Enum Format for Java
application/json	json	JSON Format
application/octet-stream	binary	Binary Format
application/xlsx	excel	Excel Format
application/xml	xml	XML Format, CData Custom Type
application/x-ndjson	ndjson	Newline Delimited JSON Format (ndjson)
application/x-www-form-urlencoded	urlencoded	URL Encoded Format
application/yaml	yaml	YAML Format
multipart/form-data	multipart	Multipart Format
text/plain	text	Text Plain Format
text/x-java-properties	properties	Text Java Properties

Note: Since DataWeave 2.3, MIME types can be specified with simple IDs such as json or xml. We will work with this syntax throughout this tutorial.

DataWeave Memory Management

DataWeave can read input data as a whole in-memory, in indexed fashion, and for some data formats, part-by-part by streaming the input.

When attempting to read a large file, it is possible to run out of memory or to impact performance negatively. Streaming can improve performance but impacts access to file.

Indexed and In-Memory:

Allow for random access to data because both strategies parse the entire document. When using these strategies, a DataWeave script can access any part of the resulting value at any time.

• Indexed: Uses indexes over the disk. DataWeave can only read the following formats in the indexed mode: CSV, JSON, XML (starting in Mule 4.3.0)
  
  Note that DataWeave does not support reading Excel (XLSX) input in the indexed mode.
• In-Memory: Parses the entire document in memory.
  
  
  DataWeave can read all supported formats using the in-memory mode.
• Streaming: Allows for sequential access to the file. This strategy partitions the input document into smaller items and accesses its data sequentially, storing the current item in memory. A DataWeave selector can access the portion of the file that is getting read.

DataWeave supports streaming only for the following formats:

CSV, JSON, Excel (XLSX, starting in Mule 4.2.2), XML (starting in Mule 4.3.0)

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