DW CLI allows executing 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.

The binary already ships with a set of modules and data formats that makes this useful for very interesting broad of use cases.

• Standar Libary
• File Module
• Http Module

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

1. Download the zip
   1. Mac |
   2. Linux
   3. Windows Very OLD :(!
2. Unzip the file on your <home_directory>/.dw
3. Add <home_directory>/.dw/bin to your PATH

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

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.

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
    

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"

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

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

• 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

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")}'

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

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}"

This example will create a very big csv and 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/

For more info about the language see the docs site

A spell is a very simple way to distribute and share a data weave transformation.

The first concept to learn is the wizard concept. A wizard is just a name that we trust and we want to have all their spells available. A wizard has a grimoire, a github repository that is inferred by https://github.com/${wizard_name}/${wizard_name}-data-weave-grimoire, that includes all the spells from this wizard.

By default there is a default wizard.

In order to add a new wizard use

dw --add-wizard <wizardName>

The wizard grimoire is going to be cloned at {Home}/.dw/grimoires

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.

Spells are just executables scripts that can be called from the command line using the Spell name.

Use dw --spell <SpellName>

dw --eval --spell Playground

It is going to execute the Playground spell that is going to be located in

{Home}/.dw/grimoires/data-weave-grimoire/Playground/src/Main.dwl

Using the --list-spells it will show all the available spells for each wizard with the documentation of each spell.

dw --list-spells

In order to become a wizard first create your github repo

https://github.com/${wizard_name}/${wizard_name}-data-weave-grimoire

Your wizard name is going to be your github user id

git clone https://github.com/${wizard_name}/${wizard_name}-data-weave-grimoire

Inside your cloned repo run

dw --new-spell <spellName>

Using VSCode and with the vscode plugin

code <spellName>

In order to test a local spell you can use

dw --local-spell ./<spellName>

Or you if you want to use a live coding XP you can use the --eval flag that it will re run the spell on every save

Once your spell is finished push it to your repo and tell your friends to try it out