Component Converter - Configuration

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Component rewrite rule configurations are managed as repository node structures. The Component Rewrite Rule Service has a reference to all available Rewrite rules that are either Node based or Service based.

Node based rewrite rule are found by searching the repository in the specified search paths. These are managed as an OSGi configuration property of the Component Rewrite Rule Service. This service has a pid of com.adobe.aem.modernize.component.impl.ComponentRewriteRuleServiceImpl, and the configuration options are:

search.paths=["/path/to/rule/root"]

Only rules found which are direct descendants of these paths will be used for search & transformations. It is important to note however, that pattern rules have no feature to distinguish between node paths for application. Any pattern that matches a node, from any tenant’s rule set, will be displayed on the conversion search results.

Teams may also register custom Service Based rules. As long as they implement the ComponentRewriteRule interface and are registered as OSGi services, they will be found and applied.

Overview

Rewrite rules are defined in two parts:

  1. One or more patterns, used for determining which transformation rule should be applied (if any) to a given node.
  2. A replacement, defining the rules for the transformation: How content should be coped and transformed to the replacement node.
<title>
  <patterns jcr:primaryType="nt:unstructured">
    <title jcr:primaryType="nt:unstructured"
           sling:resourceType="geometrixx/components/title"/>
  </patterns>
  <replacement jcr:primaryType="nt:unstructured">
    <title jcr:primaryType="nt:unstructured"
           jcr:title="${'./jcr:title'}"
           linkURL="${'./href'}"
           sling:resourceType="geodemo/components/content/title"
           type="${'./type'}"/>
  </replacement>
</title>

Ranking (Optional)

A rewrite rule may specify an optional cq:rewriteRaking property. This can be used to prioritize one rule over others, when there may be multiple matches.

Patterns

Each rewrite rule has a node containing a set of patterns. This ‘wrapping’ node must be named patterns, otherwise the rule will be ignored. Each child node of this parent are pattern rules against which nodes are matched for comparisons.

Pattern

Pattern nodes are effectively a set of properties and optional node tree which must be matched to apply the replacement rules. The name of each pattern node is arbitrary.

<patterns jcr:primaryType="nt:unstructured">
  <title jcr:primaryType="nt:unstructured"
         sling:resourceType="geometrixx/components/title"/>
</patterns>

Each property of the pattern must be matched exactly for this rule to be applied. This generally includes, at a minimum:

  • The primary node type
  • The sling:resourceType property’s value.

Patterns may also specify any other arbitrary properties, child nodes, or entire trees to be matched. The rules for matching are universal - every property and node of the source node must match the expected rule’s entire hierarchy, property for property, node for node - with one allowed exception: Optional children.

“Like” Sling Resource Type Support (v2.1)

With the release of v2.1, the sling:resourceType property allows configurations to use a “relative” path for matching. The patterns shown below will all match any component with the resource type aem-modernize/components/text:

<patterns jcr:primaryType="nt:unstructured">
  <text jcr:primaryType="nt:unstructured"
      sling:resourceType="aem-modernize/components/text"/>
</patterns>

<patterns jcr:primaryType="nt:unstructured">
  <text jcr:primaryType="nt:unstructured"
      sling:resourceType="components/text"/>
</patterns>

<patterns jcr:primaryType="nt:unstructured">
  <text jcr:primaryType="nt:unstructured"
      sling:resourceType="text"/>
</patterns>

Note: that this does require more consideration in defining the patterns, as every node with any resource type that ends with text will have the rules applied. This may have negative, unintended effects.

Rewrite Optional

<patterns jcr:primaryType="nt:unstructured">
  <lead jcr:primaryType="nt:unstructured"
        sling:resourceType="geometrixx/components/lead">
    <items jcr:primaryType="nt:unstructured"
           cq:rewriteOptional="true"/>
  </lead>
</patterns>

The pattern allows for optional child ancestors; by specifying the property cq:rewriteOptional to a node in the pattern, if that node does not exist in the repository, it will not fail the match rule. If the node does exist, the rule will apply the same full equivalency match requirements.

Replacement

Regardless of how many patterns are specified, there is only one replacement definition. This node structure prescribes the new structure that will replace any found nodes.

<replacement jcr:primaryType="nt:unstructured">
  <title jcr:primaryType="nt:unstructured"
         jcr:title="${'./jcr:title'}"
         linkURL="${'./href'}"
         sling:resourceType="geodemo/components/content/title"
         type="${'./type'}"/>
</replacement>

A replacement definition may choose to specify no replacement structure. If this is the case, the original node will be removed, and no replacement or transformations made.

Replacement definitions contain one child node containing all of the replacement rules, any additional children beyond the first are ignored.

Any original content (property or child nodes) that are not referenced by the replacement definition are ignored, and will not be on the resulting replacement node.

Static Values

Replacement definitions can contain any number of static properties to set. The existence or value of any like-named property on the original node is ignored.

Every replacement will contain static values for the jcr:primaryType and sling:resourceType properties.

Copying Properties

Properties can be copied from the original node to its replacement. These definitions can also apply some simple transformative operations during the copy. For more advanced capabilities, see the Rewriting Properties section.

<replacement jcr:primaryType="nt:unstructured">
  <title jcr:primaryType="nt:unstructured"
         jcr:title="${'./jcr:title'}"
         linkURL="${'./href'}"
         sling:resourceType="geodemo/components/content/title"
         type="${'./type'}"/>
</replacement>

Property copies are identified with the expression syntax ${ }. The value within the expression identifies the property to find on the original node. These examples show the use of single quotes ' to encapsulate the property name. This is necessary for any properties containing a colon :. However, we recommend their use on all expressions.

Simple Copy

<replacement jcr:primaryType="nt:unstructured">
  <example
      jcr:primaryType="nt:unstructured"
      prop="${'./some/prop'}"
      sling:resourceType="example/resource/type"/>
</replacement>

This example shows the simplest use case - copying a value from an original property. The original node will be searched for the property at ./some/prop. If it is found, it will be set to the replacement node’s prop property. If the the original property is not found, this replacement rule is ignored, and the property prop will not be set.

Boolean Negation

<replacement jcr:primaryType="nt:unstructured">
  <example
      jcr:primaryType="nt:unstructured"
      booleanValue="!${'./some/boolean/prop'}"
      sling:resourceType="example/resource/type"/>
</replacement>

Properties that are of type boolean can be negated during the copying operation.

Default Value

<replacement jcr:primaryType="nt:unstructured">
  <example
      jcr:primaryType="nt:unstructured"
      foo="${'./some/missing/prop':bar}"
      sling:resourceType="example/resource/type"/>
</replacement>

The default handling of a missing property is to ignore it during the transformation. However, if desired, a default value can be specified instead. In this example the property foo will be set to the value bar.

If/Else Option

<replacement jcr:primaryType="nt:unstructured">
  <example
      jcr:primaryType="nt:unstructured"
      foo="[${'./some/missing/prop'}, ${'./exists'}]"
      sling:resourceType="example/resource/type"/>
</replacement>

Another option for handling a missing property is to set the value a secondary option. This example shows that the property foo of the new node, will be set too the value of the original node’s ./exists property.

Rewriting Properties

In some cases, a more robust transformation is needed for string properties. This can be achieved by specifying a rewrite property node.

<replacement jcr:primaryType="nt:unstructured">
  <example
      jcr:primaryType="nt:unstructured"
      foo="[${'./some/missing/prop'}, ${'./exists'}]"
      sling:resourceType="example/resource/type">
    <cq:rewriteProperties
        jcr:primaryType="nt:unstructured"
        rewrite-remove-prefix="[(?:prefix-)(.+), $1]"
        rewrite-remove-suffix="[(.+)(?:-suffix), $1]"
        rewrite-concat-tokens="[(.+)(?:-separator-)(.+), $1$2]"
        rewrite-single-operand="[(?:prefix-)(.+)]"
        rewrite-boolean="[(.+), edited-$1]"
        foo="[(?:prefix-)(.+), $1]"
    />
  </example>
</replacement>

A replacement definition may contain a cq:rewriteProperties node, containing regular expression rules for transforming string properties of the original node.

Each property of the cq:rewriteProperties node must match property definition contained in the original replacement list, otherwise it will be ignored.

Each property of this node will contain string array containing two values:

  1. The regular expression used for matching the original value, including any grouping rules.
  2. The replacement to apply to the string - grouping references from the regular expression are supported.

In the example shown, the foo property originally contains the string value: prefix-removed. This is copied to the new property, then the rewrite rules are applied, and the value is updated and finalized to the string: removed.

Rewrite Map Properties

While the rewriteProperties feature supports regex processing; this has limitations in that the value generated is based on or derived from the original. Using this feature, a cq:rewriteMapProperties node can be specified to convert a given property’s value from one explicitly matched value to another.

This allows the pattern to exclude defining the original value of a property (and thus requiring more than one rule), but still provide a means to transform it to a new value.

The replacement must copy the original value to the target node, for it to be processed. Each child of the cq:rewriteMapProperties node defines the source value and desired output. If the source property is not listed as a child node, it is not modified. If the source property is listed but the value is not found in the properties of the node, it is not modified.

As an example, lets take this as a set of source content:

{
  "rewriteMapPropertiesOne": {
    "jcr:primaryType": "nt:unstructured",
    "sling:resourceType": "aem-modernize/components/rewriteMapProperties",
    "rewrite-map": "One"
  },
  "rewriteMapPropertiesTwo": {
    "jcr:primaryType": "nt:unstructured",
    "sling:resourceType": "aem-modernize/components/rewriteMapProperties",
    "rewrite-map": "Two"
  },
  "rewriteMapPropertiesThree": {
    "jcr:primaryType": "nt:unstructured",
    "sling:resourceType": "aem-modernize/components/rewriteMapProperties",
    "rewrite-map": "Three"
  }
}

Given this rule:

{
  "rewriteMapProperties": {
    "jcr:primaryType": "nt:unstructured",
    "patterns": {
      "jcr:primaryType": "nt:unstructured",
      "pattern": {
        "jcr:primaryType": "nt:unstructured",
        "sling:resourceType": "aem-modernize/components/rewriteMapProperties"
      }
    },
    "replacement": {
      "jcr:primaryType": "nt:unstructured",
      "rewriteProperties": {
        "jcr:primaryType": "nt:unstructured",
        "rewrite-map": "${'./rewrite-map'}",
        "sling:resourceType": "aem-modernize/components/rewritten",
        "cq:rewriteMapProperties": {
          "jcr:primaryType": "nt:unstructured",
          "rewrite-map": {
            "jcr:primaryType": "nt:unstructured",
            "One": "First",
            "Two": "Middle",
            "Three": "Last"
          }
        }
      }
    }
  }
}

The following outputs would be generated:

{
  "rewriteMapPropertiesOne": {
    "jcr:primaryType": "nt:unstructured",
    "sling:resourceType": "aem-modernize/components/rewritten",
    "rewrite-map": "First"
  },
  "rewriteMapPropertiesTwo": {
    "jcr:primaryType": "nt:unstructured",
    "sling:resourceType": "aem-modernize/components/rewritten",
    "rewrite-map": "Middle"
  },
  "rewriteMapPropertiesThree": {
    "jcr:primaryType": "nt:unstructured",
    "sling:resourceType": "aem-modernize/components/rewritten",
    "rewrite-map": "Last"
  }
}

Rewrite Consolidate Properties

This feature allows conversions merge a number of properties into a single a multi-value String property. When the consolidation has been completed, the original copied properties are removed. To keep the original, copy the value into a temp property for the consolidation. Unknown, or non-existing properties are ignored.

{
  "rewriteConsolidateProperties": {
    "jcr:primaryType": "nt:unstructured",
    "patterns": {
      "jcr:primaryType": "nt:unstructured",
      "rewriteConsolidateProperties": {
        "jcr:primaryType": "nt:unstructured",
        "sling:resourceType": "aem-modernize/components/rewriteConsolidateProperties"
      }
    },
    "replacement": {
      "jcr:primaryType": "nt:unstructured",
      "rewriteConsolidateProperties": {
        "jcr:primaryType": "nt:unstructured",
        "jcr:title": "${'./jcr:title'}",
        "jcr:description": "${'./jcr:description'}",
        "sourcedoesnotexist": "${'/sourcedoesnotexist'}",
        "cq:styleIds": "separator-clear",
        "sling:resourceType": "aem-modernize/components/rewriteConsolidateProperties",
        "cq:rewriteConsolidateProperties": {
          "consolidated": [
            "jcr:title",
            "jcr:description",
            "doesnnotexist",
            "sourcedoesnotexist"
          ],
          "cq:styleIds": ["cq:styleIds"]
        }
      }
    }
  }
}

Copying Children

<replacement jcr:primaryType="nt:unstructured">
  <lead jcr:primaryType="nt:unstructured"
        jcr:description="${'./jcr:description'}"
        jcr:title="${'./jcr:title'}"
        sling:resourceType="geodemo/components/content/lead"
        cq:copyChildren="{Boolean}true"
  />
</replacement>

Some source nodes are not single items, they may be a tree of content that needs to be coped to the destination. Setting the the cq:copyChildren property of the replacement node to true to perform this operation. The children of the matched source node are copied to the destination, order and names preserved.

Renaming and Reordering Children

<replacement jcr:primaryType="nt:unstructured">
  <lead jcr:primaryType="nt:unstructured"
        jcr:description="${'./jcr:description'}"
        jcr:title="${'./jcr:title'}"
        sling:resourceType="geodemo/components/content/lead"
        cq:copyChildren="{Boolean}true" >

    <items jcr:primaryType="nt:unstructured"
           cq:rewriteMapChildren="./notItems"
           cq:orderBefore="nextNode" />
  </lead>
</replacement>

In the event that the child nodes need to be renamed or reordered, additional rules are necessary. Similar to the property rewrite, a node definition is used to configure the transformation process.

The name of the node should be the desired new name on the replacement tree. This will contain the rules for the conversion. The cq:rewriteMapChildren property is used to specify which original node should be renamed. Order is managed by setting the cq:orderBefore property to the node which should be next in the order.

Final Node Definition

<replacement
    jcr:primaryType="nt:unstructured"
    cq:rewriteFinal="{Boolean}true" >

  <lead jcr:primaryType="nt:unstructured"
        jcr:description="${'./jcr:description'}"
        jcr:title="${'./jcr:title'}"
        sling:resourceType="geodemo/components/content/lead"
        cq:copyChildren="{Boolean}true" >

    <items jcr:primaryType="nt:unstructured"
           cq:rewriteMapChildren="./notItems"
           cq:orderBefore="nextNode" />
  </lead>
</replacement>

A replacement node or it’s children may specify an optional cq:rewriteFinal property. This is used to flag that the associated tree of content is a final transformation, and need not be scanned again.

Aggregation of Rules

Learn More 
<teaser jcr:primaryType="nt:unstructured"
    jcr:title="GeoDemo Teaser"
    cq:rewriteRanking="1">
  <aggregate jcr:primaryType="nt:unstructured">
    <patterns jcr:primaryType="nt:unstructured">
      <imagePattern
          jcr:primaryType="nt:unstructured"
          sling:resourceType="foundation/components/image"/>
      <titlePattern
          jcr:primaryType="nt:unstructured"
          sling:resourceType="geometrixx/components/title"/>
      <textPattern
          jcr:primaryType="nt:unstructured"
          sling:resourceType="foundation/components/text"/>
    </patterns>
  </aggregate>
  <replacement jcr:primaryType="nt:unstructured">
    <text
        jcr:primaryType="nt:unstructured"
        sling:resourceType="geodemo/components/content/teaser"
        jcr:title="${'./[pattern:titlePattern]/jcr:title'}"
        jcr:description="${./[pattern:textPattern]/text}"
        textIsRich="${./[pattern:textPattern]/text}"
        fileReference="${'./[pattern:imagePattern]/fileReference'}"
    />
  </replacement>
</teaser>

Aggregation rules allow teams to specify a sequence of patters that must be matched explicitly, and that will be replaced with a single output node. Component consolidation is used to reduce the number of custom components, or update a set reference to use Core Components. In the example above, the rule will convert the pattern of an image, title, and text node set, into a single Teaser Core Component proxy.

Since the names of the nodes are unknown during the conversion process, the [pattern:????] reference is used to determine from which node a given property should be copied. Thus:

jcr:description="${./[pattern:textPattern]/text}"

Will set the jcr:description property to the value found in the text property, of whichever node matched that pattern rule. All the rewrite rules are a available in the replacement definition.

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