Versions Compared

Old Version 5

changes.mady.by.user Alexis Rombaut

Saved on

compared with

New Version 6

changes.mady.by.user An De Moor

Saved on

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.

...

When putting a string in metadata sidecar that has the pattern #{...} it will be evaluated using the Spring Expression Language. Inside an expression, you can reference the metadata using R(<Dotted key>) or record(<Dotted key>) for example R('Descriptive.Title') or record('Descriptive.Title'). Only dotted keys having a field definition are allowed.

Info

The R takes an optional second argument, which is the default value when the metadata field is not present.

...

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

Example Expression

Example Output

Top

SimpleField

String

R('Descriptive.Title')

My title

Top

ListField

List of Strings

R('Descriptive.Keywords')

["A", "B", "C"]

Top

MapField

Map of Strings

R('Structural.Versioning')

{"Status": "HEAD", "Version": "2"}

Top

MultiItemField

Map of List of Strings

R('Descriptive.Authors')

{"Authors": ["Cedric"], "Director": ["Alice", "Bob"]}

Top

Others

Not allowed

Sub

Child of ListField

List of Strings

R('Descriptive.Keywords.Keyword')

["A", "B", "C"]

Sub

Child of MultiItemField

List of Strings

R('Descriptive.Authors.Director')

["Alice", "Bob"]

Sub

Child of MapField

String

R('Structural.Versioning.Status')

HEAD

Sub

Other

Not allowed

Output after evaluating the expression

After evaluating all expressions in the input metadata sidecar, the result is a new metadata sidecar in JSON. The conversion follows the following rules

Output after evaluating the expression

Conversion into JSON

String

JSON string

Boolean

JSON boolean

Long

JSON number

List<String>

JSON array

Map<String>

JSON object

Map<String,List<String>>

JSON object containing JSON arrays

Notice how the string "#{{R('Dynamic.CustomTag')}}" is evaluated into an array ["My custom tag"]. The end result is a valid metadata sidecar for “Keywords” namely "Keywords": {"Keyword": ["My custom tag"]} whereas before evaluating the expression "Keywords": {"Keyword": "#{...}"} is not a strictly valid metadata sidecar because the value of "Keyword" must be an array and not a string.

...