6.2. Custom Xpath widget

The custom Xpath widget can be used to retrieve elements from the XML document that are not available in widgets linked to a particular element.

Xpath is a language for identifying the elements of an XML structure. The configuration of the widget consists in composing an access path for the element of the XML document. This path consists of the nodes (elements, attributes, processing instructions, etc.) linked together by path expressions.

Figure 23. Example of the path

Example of the path

[Note]

The use of path expression types is described in Table 1, “Most Common Path Expressions”.

The Information block contains information that is not published by default. The custom XPath widget allows them to be published.

Elements that can be retrieved from the style sheet via xpath, must also be placed in the Information block of the XML document:

Figure 24. Example of the Information block and its contents

Example of the Information block and its contents

Procedure 42. To compose the xpath:

  1. In the Information block, select the desired element.

  2. In the Context, locate the name of this element.

    Figure 25. Example of an element name in Context

    Example of an element name in Context

    [Note]

    These names are part of the naming convention according to the DocBook standard and are displayed in the tooltip when hovering over each element.

  3. In the studio, drag the widget into the preview area. Click on to the right of the widget name.

  4. In the XPath field of the studio, place the nodes represented by the names of the elements. Precede each name with d: and separate with /. Since the elements are placed in the Information block, the path will start with d:info/.

    [Important]

    For xpath elements in the header or footer, the path must start with /*/.

    This allows the style sheet to retrieve the element for all the page sequences generated by the structure elements (chapters, sections, preface, etc.) present in the document.

    Figure 26. Example of location path in header or footer

    Example of location path in header or footer
[Important]

For the element imageobject to be correctly interpreted by the style sheet, it is necessary to apply the apply-templates:

Figure 27. Example of the setting for an image

Example of the setting for an image

Setting the xpath to select particular elements of the same type

It is possible to retrieve several elements of the same type (several images, several tables, etc.) in the style sheet via xpath.

Here is the example of the image recovery procedure.

  1. Place all the necessary images in the Information block > Cover.

  2. Give each image a different value in the role attribute by selecting the imageobject element.

    Figure 28. role attribute for imageobject

    role attribute for imageobject

  3. Compose the xpath for each image as follows in the example: d:info//d:imageobject[@role='image_produit'].

Table 1. Most Common Path Expressions

Syntax

Use

Example

d:

indicates that the element belongs to the DocBook namespace.

d:info/d:date

/

used to select children of an element. It indicates that we want to select an element that is directly under the parent element.

d:info/d:date

For the example given, the date element is a child of the info element.

//

used to search items in depth.

d:info//d:date

For the given example, we will search for all the date elements that are in the info block regardless of their parents.

*

selects all items.

d:info/d:legalnotice/d:*

[]

used to filter selected items based on their attributes or values. Or to represent an index in a list.

d:info/d:legalnotice[2]

For the given example, the xpath selects the second legalnotice element, child of the info element.

@

selects attributes.

d:info/d:date[@role='anniversaire']

For the given example, we select the imageobject elements that have the role attribute with the value “anniversary”.


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6. Widgets 
 6.3. Grid widget