|This page is under development as part of the EPrints 3.0 manual. It may still contain content specific to earlier versions. Manuals for previous versions of EPrints are also available.|
Metadata Field Types
There are many different types of metadata field. The type controls how a field is rendered, indexed, searched and so forth. A field always has a type and a name property, and usually has several more. Most properties are documented on this page, but some properties are only available to certain types of field, and they are listed on the page for that field.
Some of these subclasses provide very rich features, others very simple. For example the url field works just like the text field except that it's only valid if it looks like a url and when rendered it is a hyper-link.
- Basic metadata field
- Boolean - TRUE or FALSE (or can be unset, of course)
- Compound - virtual field, joins together several "multiple" fields. eg. author_name and author_email
- Multilang - allows language variants of a field. eg. titles in French, German and/or English.
- Date - stores a date.
- Time - stores a date and time.
- File - virtual field represtenting the files in a document
- Float - stores a floating point value
- Id - deprecated (do not use)
- Int - a positive integer value
- Search - a serialised search
- Set - a limited set of options
- Arclanguage - as for set, but the options are the valid languages of this repository
- Fields - as for set, but the options are the fields in a dataset.
- Langid - used internally by multilang fields to store the language id.
- Namedset - like a normal set, but takes its options from a namedset configuration file.
- Subject - possible values are taken from the Subject heirarchy.
- Subobject - a virtual field, similar to itemref, but representing an object or objects which are sub-parts of the current object (as oppose to just related in some way)
- Text - the basic text field. Maximum 255 bytes. nb. uft-8 means some chars take more than one byte.
These can be customised in the user_fields.pl and eprint_fields.pl files. Note that changing these files does not automatically modify the underlying database so should (generally) only be done before the database is created. Some metadata properties do not affect the database, and are marked as such.
If you add or remove fields, or modify a property which affects the database then you'll need to alter the database to match. In 3.0 this must be done by hand, but we have plans to build a tool to do this for you.