EPScript

From EPrints Documentation
Revision as of 19:03, 23 May 2007 by WikiSysop (Talk | contribs)

Jump to: navigation, search

EPrints 3 Reference: Directory Structure - Metadata Fields - Repository Configuration - XML Config Files - XML Export Format - EPrints data structure - Core API - Data Objects


XML Configuration: EPScript - Control Format (EPC) - Citation - Workflow - Phrase - Template - XPAGE (static pages)

This is an introduction.

Parameters

$config{xxx} - a value from the configuration.

$current_user - the current user, e.g., $current_user{username}

$current_lang - the id of the current language (such as 'en')

$item - the current item (usually an eprint, but not always, e.g., in citations or workflows for user objects), e.g., $item{eprintid}. If you just use eprintid it is a shortcut for $item{eprintid}

Data Types

EPScript allows for two primitive data types (string and integer) as well as providing the means to access properties of data objects such as EPrints or Users.

Primitive Types

Strings and characters

These are contained within either double quotes ("") or single quotes (''). There is no difference between the two, but it may be easier to use one sort when inside an XML attribute. For example:

<when test="type = 'patent'">
...  
</when>

Integers

Integers are defined as a string of numbers from 0-9, e.g. 300. Leading zeros do not have any effect, and decimal values are currently not supported.

Booleans

True or false values. Returned by = gt and lt and oneof and used in <if> etc.

Data Objects

Data Objects include most of the key EPrints objects - whether an EPrint itself, documents related to the EPrint, or a user. EPScript treats all of these data objects the same, with a simple approach to retrieve properties. When an EPScript is executed, an 'item' object is supplied. In the case of a citation file, this will be the item for which the citation is being created. For a workflow, this will be the object on which the workflow acts (e.g. an EPrint or a user). Properties of main objects can be accessed using a shortened approach - the following example is from a user workflow, so the usertype property is available:

<if test="usertype = 'editor'">
...
</if>

There are cases, however, where two or more data objects may be provided - such as an EPrint and a user. Here the main item can still be accessed in the short form, but other objects use a dollar notation. In this example, the EPrint is available as $eprint:

<if test="$eprint.ispublished.one_of('unpub', 'submitted', 'inpress')"> (<print expr="$eprint.ispublished" />)</if>

Field Values

Values associated with a data object field. The field which the value belongs to can effect how it is rendered, and compared to other values.

Hash

This currently only used by the $config parameter to give access to configuration options. Get values out of it the same way you get values from a dataobejct, eg. $config{'base_url'}

XHTML

The citation method returns a pre-rendered value. You can't do anything with XHTML other than print it.

Operators

Logical Operators

and

Returns true if both the left-hand and the right-hand expressions return true.

<if test="type = 'book' and is_set( creators )">
...
</if>

or

Returns true if at least one of the expressions returns true.

<if test="type = 'book' or type = 'patent'"> 
...
</if>

not

Returns true if the expression is false and false if the expression is true.

<if test="!is_set( creators )">
...
</if>

Comparison Operators

lt

Returns true if the left-hand expression is less than the right-hand expression. This is only applicable to expressions that return numeric values.

<if test="length(editors) lt 6">
...
</if>

gt

Returns true if the left-hand expression is greater than the right-hand expression. This is only applicable to expressions that return numeric values.

<if test="length(editors) gt 1">
...
</if>

equals

Returns true if the left-hand expression is equal to the right-hand expression. This applies to numeric, boolean, and string values.

<if test="type = 'patent'">
...
</if>

If the left OR the right value is a FIELDVALUE of a multiple field, then it returns true if the other value matches any of the values on the other side. eg. "subjects = 'group_foo'" will be true if any of the subjects are "group_foo".

not equals

The inverse of the equals operator, this returns true if the expressions are not equal.

<if test="type != 'book'">
...
</if>

Functions

Calling Functions

Functions can be called in two ways:

<when test="is_set( creators )">

or

<when test="creators.is_set">

These are interchangable, but it may be beneficial to use a specific form in some cases.

Generic Functions

is_set

Returns true if the parameter is set, based on the following criteria:

  • If the parameter is a string, it is set if it is not empty.
  • If the parameter is a list or a complex structure, it is set if at least one value is set.
<when test="is_set( creators )">
...
</when>

List Functions

length

Returns the number of items in the list.

<if test="length(editors) gt 1">s</if>

String Functions

one_of

Returns true if the string is in the list of strings provided.

<when test="type.one_of( 'book','book_section' )">
...
</when>

reverse

Returns the reverse of a string (i.e. 'abc' becomes 'cba').

<when test="type.reverse = 'tnetap'">
...
</when>

Examples

Pluralising the editors of a book

<if test="type = 'book' and is_set(editors)">
  <print expr="editors" />, (ed<if test="length(editors) gt 1">s</if>
</if>

Rendering the URL of an EPrint

<print expr="$config{base_url}" />/<print expr="eprintid" />/