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====== Greenstone 3 Format Statements ======


Greenstone3 uses XSL to dynamically generate all of the pages in your library. This provides a way to present different content in a consistent way. 

Format statements are a way to customize the look of a collection/library //without// using XSL. While it is possible to use format statements in any of the interface XSL files, this page will focus on using them in the **Format Features** section of the **Format** panel in the GLI. 

Format statements must be written in well-formed XML. XML syntax is very similar to HTML. [[http://www.w3schools.com/xml/xml_syntax.asp|W3Schools]] provides a list of the basic XML syntax rules. The Format Features section automatically checks your XML and errors will appear in the **XML Validation** text box. 

This page provides an overview of format statements. There is also a [[gs3_list_of_format_options|list of formatting elements]] that can go in format statements. 

===== Format Features =====
In the Format panel of the GLI, there is a Format Features section. This is where you can customize how parts of your collection will appear. Any changes made in the GLI will only effect the current collection (though, you can copy formatting into future collections by basing them on another collection). There are different types of pages in your collection, and you can select which page or pages you want your format changes to effect. For example, if you want to modify how search results will appear, you would modify the **search** format feature. If you want to modify how documents will be listed in all of your browsing classifiers, you would modify the **browse** format feature. If you want to modify just how the first browsing classifier will appear, you can select that classifier from the **Choose Feature** dropdown menu and click the **Add Format** button. The individual classifier will then have its own personal format feature for you to edit. The following table shows the different format features available in the GLI. 

^Format Feature^Description^
|''browse''|Format will effect all browsing classifier pages|
|''searchType''|This feature is unique. It determines which types of search will be available; plain must be in the list for the quick search box to appear in the interface|
|''search''|Format will effect all search and search result pages in the collection|
|''global''|Format will effect all pages in the collection|
|''display''|Format will effect the document display pages|
|''CL1'',''CL2'', etc.|Format will effect the specific classifier page; format templates here will override  format in the ''browse'' feature|

//**SearchType** is a unique feature: it is simply a list of the types of search pages you want in your collection. It defaults to include all three possible types. You can remove any of them, though, if you remove the "plain" search, the quick search box will not appear in the interface. The SearchType feature is ignored for the rest of this page, as it does not deal with format statements.//


So, each feature effects certain (or, for the **global** feature, potentially all) pages in the collection. To make these changes, you can add or modify one or more **templates** to the feature. 


===== Templates =====
{{:en:templates2.png?direct&500 |}}
**Templates** are the containers for format statements. Different templates effect different parts of the page. For example, some basic templates for browse pages include:
  * **documentNode**: Determines the display for each document (outlined in blue)
  * **classifierNode[@classifierStyle = 'VList']**: Determines the display for each hierarchical item (outlined in orange)
  * **classifierNode[@classifierStyle = 'HList']**: Determines the display for each item in the horizontal partitions (outlined in green)

//A browsing classifier may not have a hierarchy and/or horizontal partitions, in which case these templates (VList and HList, respectively) will be ignored.//

A simple **documentNode** classifier might look like this (The result of this format statement on a basic list browsing classifier is shown below):

<code xml>
  <gsf:template match="documentNode">
    <td>
      <gsf:icon type="document"/>
    </td>
    <td>
      <gsf:link type="document">
        <gsf:metadata name="dc.Title"/>
      </gsf:link>    
    </td>
  </gsf:template>
</code>
\\
{{ :en:simple-format.png?direct&200|}}
Notice the ''<gsf:template match="documentNode">'' tag at the beginning. This signals the start of the formatting to be used for every **documentNode** on the page (i.e. every document that will be listed on the given page). The final ''</gsf:template>'' signals the end of the format statement. Everything in between these two tags will be displayed for each document.

By default, browsing pages and search results are displayed using HTML tables, and every document has its own table row. For this reason, everything in our format statement is inside of a table cell tag (''<td>''). Inside the ''td'' tags, there are 3 important format statements:
  * ''<gsf:icon type="document"/>'': This displays a document icon.
  * ''<gsf:link type="document"> ... </gsf:link>'': This creates an HTML link to the document's display page.
  * ''<gsf:metadata name="dc.Title"/>'': This will display the value (or values) of **dc.Title** for this document, if there are any. Since this is inside the ''gsf:link'' tags, this becomes a link to the document display page. 

These are examples of the most common format statement types. The following sections will look at each of these in turn, followed by the more complex **conditional** format statements.


===== Links =====
**Link** statements provide an easy way to link to document display pages, source documents, and classifier pages, as well as to associated documents. Link statements work like ''<a>'' tags in HTML (in fact, that is what they become when Greenstone generates the page). Take this sample HTML code:

<code html>
<a href="http://www.google.com">This is a link to Google!</a>
</code>

Everything in between the ''a'' tags (in this case, the text "This is a link to Google!") becomes a link to the website specified in the ''href'' attribute (in this case ''http://www.google.com''). 

Greenstone link statements work in a similar way, except instead of specifying the exact URL to link to, you specify the //type// of page to link to: //document//, //source//, or //classifier//. 

In a **documentNode** template, you will likely want to link to either the document's display page in Greenstone or the source document itself (or both):

<code xml>
<gsf:template match="documentNode">
   <gsf:link type="document">
      A link  with type 'document' links to the document's display page in Greenstone.
   </gsf:link>
   <gsf:link>
      A link with NO type also links to the the document's display page in Greenstone. 
   </gsf:link>
   <gsf:link type="source">
      A link with type 'source' links to the source document itself, e.g. PDF, Word, JPG, etc. 
   </gsf:link>
</gsf:template>
</code>

\\

In a **classifierNode** template, you will generally have a link to the classifierNode, so that the user can click the node to see the items it contains (in a VList for a hierarchical subject classifier, they may click a subject to see all of the documents that have that subject; in an HList for a title classifier, they may click on a letter to see all documents with a title beginning with that letter). This is the default HList template, which has a classifier link:

<code xml>
  <gsf:template match="classifierNode[@classifierStyle = 'HList']">
    <gsf:link type="classifier">
      <gsf:metadata name="Title"/>
    </gsf:link>
  </gsf:template>
</code>
\\

The final link type is slightly different. If you have specified associated documents for any items in your collection (generally, associated documents will be the same document in a different format), you can also add a link for these in the **documentNode** template:

<code xml>
<gsf:metadata name="equivDocLink"/>
   This is a link to an associated/equivalent document.
</gsf:metadata name="/equivDocLink"/>
</code>



===== Icons =====

Greenstone format statements make it easy to quickly add in icons. ''gsf:icon'' statements link to a particular icon:

  * ''<gsf:icon type="document"/>'' and ''<gsf:icon/>'' will display this icon: {{:en:itext.gif?direct&|}}  
  * ''<gsf:icon type="classifier"/>'' will display this icon: {{:en:bshelf.gif?direct&|}}
//(These icons are stored in ''Greenstone3/web/interfaces/default/images'' as ''itext.gif'' and ''bshelf.gif'', respectively. So, a quick way to display your own icons is to replace these files.//

The remaining icon statements are dependent on the metadata of the document: 

  * ''<gsf:metadata name="srcicon"/>'' will display the appropriate icon for the source document if Greenstone has it. For example, it will display {{:en:ipdf.gif?direct&20|}} for PDF documents, {{:en:ippt.gif?direct&20|}} for Powerpoint documents, and {{:en:imp3.gif?direct&30|}} for MP3s. If Greenstone does not have an icon for a document type, nothing will be displayed.
  * ''<gsf:metadata name="thumbicon"/>'' will display a thumbnail for images (defaults to a width of 100px, but this can be changed using the ''thumbnailsize'' option in the [[en:plugin:ImagePlugin]].
  * ''<gsf:metadata name="screenicon"/>'' will display a larger version (width of 500px) of the image than the thumbnail.


===== Document Metadata =====

Any metadata that has been extracted from or added to documents can be referenced in format statements using the ''gsf:metadata'' tag. Metadata is referred to by its element name. For example, if you have provided ''dc.Title'' metadata for your documents, ''<gsf:metadata name="dc.Title"/>'' will display these values.

If you want to display the file name for documents, use ''<gsf:metadata name="Source"/>''. //(Note that the metadata name does not include the ''ex.'' namespace. Extracted metadata is referred to without the namespace in format statements. Metadata in all other namespaces--e.g. ''dc.'', ''gs.'', ''dls.'', etc.--__does__ require the namespace, as shown in the ''dc.Title'' example above.)//


The metadata tag can have additional, optional attributes: //select//, //separator//, //format// and //pos//.

==== Separator ====
When there are multiple values for a metadata field (for example, a document has two ''dc.Title'''s), by default Greenstone will display all of the values separated by a comma. You can change the separator by specifying a value for the separator attribute. For example, you could separate values with a semi-colon like this: ''<gsf:metadata name="dc.Title" separator="; "/>''.

==== Position ====
Sometimes, when there are multiple values for a metadata field, you only want to display a particular one. You can do this by specifying the //pos// attribute: ''<gsf:metadata name="dc.Title" pos="1"/>'' will display the first dc.Title listed for a document;  ''<gsf:metadata name="dc.Title" pos="2"/>'' will display the second, etc. pos values of ''first'' and ''last'' can also be used instead of numbers.

''pos="classifiedBy"'' can be used in classifiers to output the metadata value that was used to classify the document into the current position. For example, if a document had two Titles, it would show up in a titles classifier in two places. Using ''<gsf:metadata name="Title" pos="classifiedBy"/>'' will ensure that the correct Title is output for each entry. Using ''<gsf:metadata name="Title"/>'' would output both Titles for both entries.

==== Format ====
The format attribute can be used to format dates and language codes:
  * ''<gsf:metadata name='Date' format='formatDate'/>'' will turn a Date value of ''20131208'' into 08 December 2013.
  * ''<gsf:metadata name='Language' format='formatLanguage'/>'' will turn a Language value of ''en'' into English.

Both of these are language dependent. That is, the month and language will be in whatever language has been selected by the user.

==== Select ====

In sectioned documents, //select// allows you to choose which section/sections (in relation to the current section) the metadata should be retrieved from. For example, if you were in section 2.5.3 of a document:
  * ''<gsf:metadata name="Title"/>'' and ''<gsf:metadata name="Title" select="current"/>'' refer to the title of the current section 2.5.3
  * ''<gsf:metadata name="Title" select="parent"/>'' is the title for section 2.5
  * ''<gsf:metadata name="Title" select="ancestors"/>'' is the titles for sections 2.5, 2, and the document
  * ''<gsf:metadata name="Title" select="root"/>'' is the document title
  * ''<gsf:metadata name="Title" select="siblings"/>'' is the titles for sections 2.5.1, 2.5.2, 2.5.4, etc.
  * ''<gsf:metadata name="Title" select="children"/>'' displays the titles for sections 2.5.3.1, 2.5.3.2, etc.
  * ''<gsf:metadata name="Title" select="descendents"/>'' displays the titles for sections 2.5.3.1, 2.5.3.1.1, 2.5.3.1.2, 2.5.3.2, 2.5.3.2.1, etc.

===== Classifier Metadata =====

Metadata for classifiers is referenced in the same way as for a document, like <gsf:metadata name="Title"/>. Classifier nodes only have a very limited set of metadata however.
  * Title - the Title metadata gives the name of the classifier or bookshelf. One thing to note is that a bookshelf label is always stored as Title metadata, regardless of what metadata the classifier was built on.
  * numleafdocs - this gives the number of documents underneath this part of the classifier.

===== Conditional =====
Conditional statements are extremely useful if you want to display different things depending on the metadata of the document. There are two different types of conditional statements: choose-metadata and switch. 

==== Choose-metadata====
Choose-metadata is relatively simple. You provide a list of metadata fields and the first of the fields with a value for that document will be displayed. If none of the fields have a value, then you can add a fall-back option (''gsf:default''). For example, the default documentNode statement includes the following:

<code xml>
        <gsf:choose-metadata>
          <gsf:metadata name="dc.Title"/>
          <gsf:metadata name="exp.Title"/>
          <gsf:metadata name="ex.dc.Title"/>
          <gsf:metadata name="Title"/>
          <gsf:default>Untitled</gsf:default>
        </gsf:choose-metadata>
</code>

In this example, Greenstone will first look for ''dc.Title'', then (if the document does not have a value for ''dc.Title'') for ''exp.Title'', then for ''ex.dc.Title'', and finally for the extracted ''Title''. The first (and only the first) of metadata field in the list that has a value will be displayed. If the document has no value for any of these fields, the word "Untitled" will be displayed.

==== Switch ====
The switch format statement allows you to display different things based on the presence or value of a certain metadata field for a given document. 

<code xml>
        <gsf:switch>
          <gsf:metadata name="dc.Creator"/>
          <gsf:when test="exists">
            <b>Author: </b><gsf:metadata name="dc.Creator"/>
          </gsf:when>
          <gsf:otherwise>
          <i>No Author</i>
          </gsf:otherwise>
        </gsf:switch>
</code>

\\
This example is testing whether or not there is a value for ''dc.Creator''. The document has one or more values for ''dc.Creator'', e.g. Dr. Seuss, "**Author:** Dr. Seuss" will be displayed. If the document does not have a value for ''dc.Creator'', "//No Author//" will appear.

You can also test the //value// of a certain document (this example first test whether ''dc.Format'' equals "Lyrics", then "Discography", and finally "Tablature", and does something different in each instance):

<code xml>
<gsf:switch>
   <gsf:metadata name="dc.Format"/>
   <gsf:when test="equals" test-value="Lyrics">
      <gsf:link type="document">
         <gsf:icon file="lyrics.gif" select="collection" />
      </gsf:link>
   </gsf:when>
   <gsf:when test="equals" test-value="Discography">
      <gsf:link type="document">
         <gsf:icon file="disc.gif" select="collection" />
      </gsf:link>
   </gsf:when>
   <gsf:when test="equals" test-value="Tablature">
      <gsf:link type="document">
         <gsf:icon file="tab.gif" select="collection" />
      </gsf:link>
   </gsf:when>
</gsf:switch>
</code>

===== Iteration =====

Sometimes a document will have more than one value for a particular metadata element. <gsf:metadata>, by default, will display all values. You can set a separator to be output in between each value. Sometimes however, you might want to output HTML around each value. In this case, you can use <gsf:foreach-metadata>, which gives more control over the output.

<code>
<gsf:foreach-metadata name="dc.Subject">
  <b><gsf:meta-value/></b>
</gsf:foreach-metadata>
</code>

In this simple example, each dc.Subject is output in bold formatting.

<code>
<gsf:foreach-metadata name="dc.Subject" separator="; ">
  <b><gsf:meta-value/></b>
</gsf:foreach-metadata>
</code>

In this example, we add in a separator too. Separator is still useful here as we don't want it output for the last value, which would happen if we put the semi colon in the body of the element.

To sort the values, add ''@sort='true' '' to the <gsf:foreach-metadata> element. Or for more sorting control, add <gsf:sort/> to the body. <gsf:sort/> mirrors <xsl:sort/>; for a list of attributes, see
[[en:user:list_of_format_options#gsfsort_attributes| this page]].

<code>
<gsf:foreach-metadata name="dc.Subject" separator="; ">
  <gsf:sort order='descending'/>
  <b><gsf:meta-value/></b>
</gsf:foreach-metadata>
</code>


===== Additional Resources =====
  * The **[[en:user:gs3_list_of_format_options|list of format statements]]** can be a useful reference when writing up format statements in Greenstone. 
  * There are some **[[en:user:gs3_sample_interface_modifications|sample GS3 format statements]]** available.
  * The templates in the GLI only effect very specific parts of the page. You may want to completely change large portions of how your Greenstone library looks. For more information on how to do this, check out the [[interfaces]] page.
  * [[http://wiki.greenstone.org/wiki/images/7/71/Skins_Doc.pdf|Greenstone 3 Interface Transformations Library: Basic Documentation]] //Maxime Roüast//