Metadata Expressions

Introduced in version 23.1
Added the method F in version 24.3

Introduction

From version 23.1 you can create a batch offering rich metadata expressions where the new metadata of the item can be determined by

The (previous) metadata of the item
Combinations of fields
Conditions
Textual operations

Usage

The expressions are currently used in the following cases

Methods

Each pattern #{...} in the expression string will be evaluated using the Spring Expression Language. Inside an expression, you can reference the metadata using R(<Dotted key>)for example R('Descriptive.Title') or F('Descriptive.Title').

Only dotted keys referring to a field definition present in the system are allowed

Method	Effect	Since

Method	Effect	Since
`R(String dottedKey)`	Outputs the value of the metadata field as defined in the table below: Batch Metadata Expressions \| The output of the metadata accessor	`23.1`
`R(String dottedKey, Object defaultValue)`	Similar to `R` but with a default value if the field is not present.	`23.1`
`F(String dottedKey)`	Similar to `R` but with the exception that lists are flattened into a string using the separator `-`	`24.3`
`F(String dottedKey, String joinSeparator)`	Similar to `R` but with the exception that lists are flattened into a string using the provided separator	`24.3`

The output of the metadata accessor

The output of the metadata accessor R or record is the following depending on which field type the dotted key refers to:

Level	Case	Effect	Accessor R	Accessor R Output	Accessor F	Accessor F Output

Level	Case	Effect	Accessor R	Accessor R Output	Accessor F	Accessor F Output
Top	SimpleField	String	`R('Descriptive.Title')`	`My title`	`F('Descriptive.Title')`	`My title`
Top	ListField	List of Strings	`R('Descriptive.Keywords')`	`["A", "B", "C"]`	`F('Descriptive.Keywords')`	`A-B-C`
Top	MapField	Map of Strings	`R('Structural.Versioning')`	`{"Status": "HEAD", "Version": "2"}`	`F('Structural.Versioning')`	Not allowed
Top	MultiItemField	Map of List of Strings	`R('Descriptive.Authors')`	`{"Authors": ["Cedric"], "Director": ["Alice", "Bob"]}`	`F('Descriptive.Authors')`	Not allowed
Top	Others	Not allowed		Not allowed		Not allowed
Sub	Child of ListField	List of Strings	`R('Descriptive.Keywords.Keyword')`	`["A", "B", "C"]`	`F('Descriptive.Keywords.Keyword')`	`A-B-C`
Sub	Child of MultiItemField	List of Strings	`R('Descriptive.Authors.Director')`	`["Alice", "Bob"]`	`F('Descriptive.Authors.Director', ', ')`	`Alice, Bob`
Sub	Child of MapField	String	`R('Structural.Versioning.Status')`	`HEAD`	`F('Structural.Versioning.Status')`	`HEAD`
Sub	Other	Not allowed		Not allowed		Not allowed

Variants

The expression can formulated in two manners

Multiple Spel expressions with textual information in between text A #{...} text B #{...}
A single Spel expression using #{...} where extra text needs to be concatenated using +

Multiple Spel = #{R('Descriptive.Title')} - #{R('Descriptive.Description')}
Single Spel = #{R('Descriptive.Title') + ' - ' + R('Descriptive.Description')}

Restrictions

The available features of SPel are for security reasons restricted to the following patterns

Literal expressions
Boolean and relational operators
Inline lists, maps, etc
Ternary operator
The method named “R”, “F” or “record”

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