Readers Pipes

those are pipes that will spit out resources, without modifying them. They are usually combined with logical and/or writer pipes

Base pipe (echo <path>)

outputs what is in input (so what is configured in path).

It's handy to set the input of a given sequence in a talkative manner:

    echo /content | write foo=bar

You can also pipe it with relative path to go to a children:

    echo /content | $ some/parent | echo child/path | ...

XPath Pipe (xpath <xpath query>)

    xpath /jcr:root/content/foo//element(*,nt:unstructured)[@sling:resourceType="foo/bar"] | write foo=bar

Traverse Pipe (traverse)

traverse current input resource's tree, outputing, as resources, either the node of the tree, either its properties

  • breadthFirst the tree visit will be done deep first, unless this flag is set to true,
  • depth max depth the visit should go to,
  • properties is a flag mentioning the pipe should traverse node's property,
  • nameGlobs filters the property that should get outputed
    echo /content | traverse @ with breadFirst=true depth=10 properties=true | ...

MultiProperty Pipe (mp)

iterates through values of input multi value property and write them to bindings

    echo /content/my/months | mp @ name currentMonth | echo /content/year/${currentMonth} | write visited=true

Sling Query Pipes

Sling Query shares with Sling Pipes the same objective to write more concise (and efficient) code for most common operations. Below are the most common Sling Query methods as reader pipes.

Find Pipe ($ <expr>)

executes find(expression) that searches through the subtree below the current input resource. Typical handy usage would be to use resource type selector like that:

    echo /content | $ foo/bar

Children Pipe (children <expr>)

executes children(expression) that searches through the immediate children of the current input resource)

    echo /content/some/container | children foo/bar

Siblings Pipe (siblings <expr>)

executes siblings(expression) that searches through siblings of current input resource

    echo /content | siblings foo/bar

Parent Pipe (parent <expr>)

executes parent() that retrieves current parent

Closest Pipe (closest <expr>)

executes closest(expression) that searches the closest parent resource of current input resource

    echo /content | $ foo/bar | closest jcr:content

will find jcr:content nodes that have foo/bar typed resource somewhere in their tree

Parents Pipe (parents <expr>)

executes parents(expression) that searches all the parents of the current input resource

InputStream reader pipes

those are specific reader pipes, that read information an input stream from defined in expr configuration, that can be:

  • a remote located file (starting with http),
  • a file located in the repository (existing file stored in the repository),
  • a file passed as request parameter with pipes_inputFile as parameter name (in that case, expr can be empty)
  • direct data stream in the expression

Json Pipe (json expr)

feeds bindings with json stream valuePath is a property as a json path like expression that defines where the json value we care about is. E.g. $.items[2] considers root is an object and that we want the 3rd item of items array, located at items key of the root object.

In case the json value is an array, the pipe will loop over the array elements, and output each one in the binding. Output resource remains each time the input one.

    json {"items":[{"val":"1"},{"val":"2"},{"val":"3"}]} @ with valuePath=$.items @ name demo | mkdir /content/${demo.val}

will create a tree of 3 resources /content/1, /content/2 and /content/3.

An interesting usage of the JSON pipe can also be to loop over an array of Strings like

    json ["/content/mySite/page1","/content/mySite/page2","/content/mySite/page3"]
    | echo ${one}
    | echo jcr:content
    | write update=something

Csv Pipe (csv <expr>)

feeds bindings with csv stream

    csv idx,val\\n1,1\n2,2\\n3,3 @ name demo
    | mkdir /content/${demo.val}

should create a tree of 3 resources /content/1, /content/2 and /content/3. You can change separator with separator property

    csv a;b @ with separator=;

Regexp pipe (egrep <expr>)

feeds bindings with text input stream, parsed with a regexp pattern, that is a regular expression, with named group (e.g. (?<user>.*)) that will be used to produce the output binding names

    egrep @ pattern=/res/(?<asset>/[\-\w\.\/0-9]+) @ name demo
    | echo /content/assets
    | write test=demo.asset