ForceSingleValueTransformer

Forces a metadata field to be single-value

importerJavadoc: ForceSingleValueTransformer

Notes

The action can be one of the following:

• keepFirst: Keeps the first occurrence found.
• keepLast: Keeps the last occurrence found.
• mergeWith:<sep>: Merges all values into one, separated by <sep>..

If you do not specify any action, the default behavior is to merge all occurrences, joining values with a comma.

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

Examples

For documents where multiple title fields are found, The following example only keeps the first title value captured.

YAML

handler:
  class: ExternalParser
  action: keepFirst
  fieldMatcher:
    pattern: title

JSON

{
  "handler": {
    "class": "ExternalParser",
    "action": "keepFirst",
    "fieldMatcher": {
      "pattern": "title"
    }
  }
}

XML

<handler>
  <class>ExternalParser</class>
  <action>keepFirst</action>
  <fieldMatcher>
    <pattern>title</pattern>
  </fieldMatcher>
</handler>

Usage

Full configuration skeleton, with every option and its default

YAML

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

JSON

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

XML

<handler>
  <class>ForceSingleValueTransformer</class>
  <action>string</action>
  <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
action	string	No	-
fieldMatcher	TextMatcher	No	TextMatcher
label	string	No	-

Property Details

action

The action can be one of the following:

"action"="[keepFirst|keepLast|mergeWith:separator]"

• keepFirst: Keeps the first occurrence found.
• keepLast: Keeps the last occurrence found.
• mergeWith:<sep>: Merges all values into one, separated by <sep>..

If you do not specify any action, the default behavior is to merge all occurrences, joining values with a comma.

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.