KeepOnlyTransformer

Retains specified metadata fields and removes all others.

importerJavadoc: KeepOnlyTransformer

Notes

Keep only the metadata fields provided, delete all other ones. Exact field names (case-insensitive) to keep can be provided as well as a regular expression that matches one or many fields (since 2.1.0).

Note: Unless you have good reasons for doing otherwise, it is recommended to use this handler as one of the last ones to be executed. This is a good practice to ensure all metadata fields are available to other handlers that may require them even if they are not otherwise required.

Can be used both as a pre-parse or post-parse handler.

Examples

The following example keeps only the title and description fields from all extracted fields.

YAML

handler:
  class: ExternalParser
  fieldMatcher:
    method: REGEX
    pattern: title|description

JSON

{
  "handler": {
    "class": "ExternalParser",
    "fieldMatcher": {
      "method": "REGEX",
      "pattern": "title|description"
    }
  }
}

XML

<handler>
  <class>ExternalParser</class>
  <fieldMatcher>
    <method>REGEX</method>
    <pattern>title|description</pattern>
  </fieldMatcher>
</handler>

Usage

Full configuration skeleton, with every option and its default

YAML

class: KeepOnlyTransformer
fieldMatcher:
  ignoreCase: false
  ignoreDiacritic: false
  matchEmpty: false
  method: BASIC
  negateMatches: false
  partial: false
  pattern: string
  replaceAll: false
  trim: false
label: string

JSON

{
  "class": "KeepOnlyTransformer",
  "fieldMatcher": {
    "ignoreCase": false,
    "ignoreDiacritic": false,
    "matchEmpty": false,
    "method": "BASIC",
    "negateMatches": false,
    "partial": false,
    "pattern": "string",
    "replaceAll": false,
    "trim": false
  },
  "label": "string"
}

XML

<handler>
  <class>KeepOnlyTransformer</class>
  <fieldMatcher>
    <ignoreCase>false</ignoreCase>
    <ignoreDiacritic>false</ignoreDiacritic>
    <matchEmpty>false</matchEmpty>
    <method>BASIC</method>
    <negateMatches>false</negateMatches>
    <partial>false</partial>
    <pattern>string</pattern>
    <replaceAll>false</replaceAll>
    <trim>false</trim>
  </fieldMatcher>
  <label>string</label>
</handler>

Properties

Property	Type	Required	Default
fieldMatcher	TextMatcher	No	TextMatcher
label	string	No	-

Property Details

fieldMatcher

Matches document fields based on specified patterns and methods

label

An optional, user-supplied label for this step in the importer pipeline. It has no effect on processing — it exists purely to help identify this step, for example in large configurations or in the visual configurator.