DW CLI

DW CLI allows to execute queries and generate data directly from the command line.

DW CLI is compiled with Graal AOT for fast bootstrap so download the one for your target OS.

What does it contains?

It includes all the modules that are included in the weave runtime. wlang
It includes file-module, http-module and raml-module from [data-weave-io]((https://github.com/mulesoft-labs/data-weave-io)
It includes dependency-management-module. This module allows to declare dependencies using annotations.
Data Formats are:

Format	MimeType	Extension
Xml	application/xml	.xml
Json	application/json	.json
CSV	application/csv	.csv
Properties	text/x-java-properties	.properties
TextPlain	text/plain	.txt
Yaml	application/yaml	.yaml
Binary	application/octet-stream	.bin
Multipart	multipart/form-data	.multipart
UrlEncoded	application/x-www-form-urlencoded	.urlencoded
NDjson	application/x-ndjson	.ndjson

How to install it?

Using Homebrew:

brew tap mulesoft-labs/data-weave
brew install dw

Manually

Download the zip Mac | Linux | Windows
Unzip the file on your <home_directory>/.dw
Add <home_directory>/.dw/bin to your PATH

From code

Execute the gradle task nativeImage

./gradlew native-cli:nativeImage

It takes several minutes so good time to take and refill your mate.

Once it finishes you will find the dw binary in native-cli/build/graal/dw

How to use it

If the directory containing the dw executable is in your PATH, you can run dw from anywhere. If it is not, go to the bin directory referenced in the installation instructions and run dw from there.

Show documentation

dw

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Usage:

dw [-p <weavePath>]? [-i <name> <path>]* [-v]? [-o <outputPath>]? [[-f <filePath>] | [-m <nameIdentifier>] | <scriptContent>]

Arguments Detail:

 --spell | Runs a spell. Use the <spellName> or <wizard>/<spellName> for spells from a given wizard.
 --update-grimoires | Update all wizard grimoires
 --add-wizard    | Downloads wizard grimoire so that its spell are accessible
 --path or -p    | Path of jars or directories where weave files are being searched.
 --input or -i   | Declares a new input.
 --verbose or -v | Enable Verbose Mode.
 --output or -o  | Specifies output file for the transformation if not standard output will be used.
 --main or -m    | The full qualified name of the mapping to be execute.
 --file or -f     | Path to the file
 --eval          | Evaluates the script instead of writing it
 --version       | The version of the CLI and Runtime
 --clean-cache   | Cleans the cache where all artifacts are being downloaded this force to download all artifacts every time

 Example:

 dw -i payload <fullpathToUser.json> "output application/json --- payload filter (item) -> item.age > 17"

 Documentation reference:

 https://docs.mulesoft.com/mule-runtime/4.3/dataweave

Query content from a file

Input file users.json

[
  {
    "name": "User1",
    "age": 19
  },
  {
    "name": "User2",
    "age": 18
  },
  {
    "name": "User3",
    "age": 15
  },
  {
    "name": "User4",
    "age": 13
  },
  {
    "name": "User5",
    "age": 16
  }
]

Let's query users old enough to drink alcohol:

dw -i payload <fullpathToUsers.json> "output application/json --- payload filter (item) -> item.age > 17"

Query content from standard input

cat <fullpathToUser.json> | dw "output application/json --- payload filter (item) -> item.age > 17"

Redirecting the output to a file

dw "output application/xml --- users: {( 1 to 100 map (item) -> {user: "User" ++ item} )}" >> out.xml

DW Important ENV variables

DW_HOME = The directory where the home will be found if not defined ~/.dw will be used
DW_LIB_PATH = The directory where libraries are going to be search by default. If not defined ${DW_HOME}/libs will be used
DW_DEFAULT_INPUT_MIMETYPE = The default mimeType that is going to be used for the standard input. If not defined application/json will be used
DW_DEFAULT_OUTPUT_MIMETYPE = The default output mimeType that is going to be if not defined. If not defined application/json will be used

Using external DW Modules with --path

This specifies the path where to search it will also search on the DW_LIB_PATH env directory path.

DIRECTORY=<pick a directory>

cd $DIRECTORY

echo '%dw 2.0
fun addUnderscore(s: String): String = s ++ "_"' > utils.dwl

dw --path $DIRECTORY 'output application/json import * from utils --- {underscored: addUnderscore("hello")}'

CURL + DW => Power API Playground

An interesting use case for the CLI is to combine it with curl

Example query github commits

We can use the Github API to query commits of a repo.

We can easily get the first commit by doing:

curl "https://api.github.com/repos/mulesoft/mule/commits?per_page=5" | dw "payload[0]"

or we can get the message by doing:

curl "https://api.github.com/repos/mulesoft/mule/commits?per_page=5" | dw "{message: payload[0].commit.message}"

HTTP POST data generated by DW

This example will create a really big csv and it will stream it to the HTTP server on localhost.

dw "output application/csv --- (1 to 10000000000000000000000) map (item) -> {name: 'User \$(item)'}" | curl -X POST -T "/dev/stdin" http://localhost:8081/

Documentation

For more info about the language see the docs site

Spells

Spells are just executables scripts that can be called from the command line using the Spell name. For example dw --eval --spell Playground It is going to execute the Playground spell that is going to be located in {User_Home}/.dw/grimoires/data-weave-grimoire/Playground/src/Main.dwl

Grimoire

A grimoire is a collection of spells from a given wizard. The default grimoire is located in data-weave-grimoire But it can also be consumed from other trusted Wizard. For example leansh/Tutorial is going to looks for a github repo called leansh-data-weave-grimoire under leansh user.

PrashantSalunke22/data-weave-native