# Automatically generated lists / directories

The speedata Publisher can create arbitrary types of directories. All lists: table of contents, list of articles or keyword index, are created by the same principle. The necessary data for the list (e.g. page number, article number) are saved in its own XML data structure, saved to the hard drive and used in the next publishing run.

To make the speedata publisher run more than once, it needs to be instructed by a switch on the command line (`sp --runs=2`) or in the configuration file with `runs=2`. You can give any number, but normally two or three runs are sufficient to generate the list.

## Step 1: Collection the information

Both commands Element and Attribute are used to structure the data, that are to be read on the next publishing run. You can create XML data structures with the information for the list that you need to generate. The data should have a structure that is suited for processing with the speedata Publisher. The following is an example of a suitable data structure:

    <articlelist>
      <article nummer="1" page="10"/>
      <article nummer="2" page="12"/>
      <article nummer="3" page="14"/>
    </articlelist>

To create this structure in the layout rules, you need to apply the commands Element and Attribute as follows:

    <Element name="articlelist">
      <Element name="article">
        <Attribute name="nummer" select="1"/>
        <Attribute name="page" select="10"/>
      </Element>
      <Element name="article">
        <Attribute name="nummer" select="2"/>
        <Attribute name="page" select="12"/>
      </Element>
      <Element name="article">
        <Attribute name="nummer" select="3"/>
        <Attribute name="page" select="14"/>
      </Element>
    </Element>

Instead of using the commands Element and Attribute in one place you can create the construct by using variables to save the data. See the example below.

## Step 2: Save and load the list information

The command SaveDataset saves the given structure to the hard drive which can be loaded again (in the next run) with LoadDataset. If the file does not exist when loading it with LoadDataset it will be silently ignored, because it could be the first run which means the file does not exist yet.

## Step 3: Process the information

Right after using LoadDataset, data processing continues with the matching rule for the\ data set file. In the example above, a rule that matches `articlelist` will be applied (Record element=“articlelist”). When this rule finishes, the layout continues right after `LoadDataset`.

## Example

The following example (planets) is included in the distribution. It creates a table of contents for the following pages. The data processing starts at the element `planets` (about the middle of the file). We load the data file `toc` (it could be any name). In the first run, this file is not found and the command LoadDataset does not execute anything. The data processing continues with the command after the `LoadDataset` (here: `>SetVariable>`). During the first run data which has the following structure is written on the disk (with the name `toc`):

    <tableofcontents>
      <planetlisting name="Mercury" pagenumber="2"/>
      <planetlisting name="Venus" pagenumber="3"/>
      <planetlisting name="Earth" pagenumber="4"/>
      <planetlisting name="Mars" pagenumber="5"/>
      <planetlisting name="Jupiter" pagenumber="6"/>
      <planetlisting name="Saturn" pagenumber="7"/>
      <planetlisting name="Uranus" pagenumber="8"/>
      <planetlisting name="Neptune" pagenumber="9"/>
    </tableofcontents>

In the layout XML file, the data structure must have this format:

    <Element name="tableofcontents">
      <Element name="planetlisting">
        <Attribute name="name" select="'Mercury'"/>
        <Attribute name="pagenumber" select="2"/>
      </Element>
      <Element name="planetlisting">
        <Attribute name="name" select="'Venus'"/>
        <Attribute name="pagenumber" select="3"/>
      </Element>
      ...
      <Element name="planetlisting">
        <Attribute name="name" select="'Uranus'"/>
        <Attribute name="pagenumber" select="9"/>
      </Element>
    </Element>

The information in the attributes should be created dynamically. We use the XPath expression `@name` and the XPath function `sd:current-page()`.

In the second run the file `toc` will be read by `LoadDataset`. The layout XML processing jumps to the `<Record element=tableofcontents">` at the beginning of the file, since `tableofcontents` is the root element of the data set.

    <Record element="tableofcontents">
      <SetVariable variable="tableofcontents" select="''"/>
      <ProcessNode select="planetlisting"/>
      <PlaceObject column="3">
        <Textblock width="20" fontface="Header">
          <Paragraph><Value>Contents</Value></Paragraph>
        </Textblock>
      </PlaceObject>
      <PlaceObject column="3">
        <Textblock width="20">
          <Value select="$tableofcontents"/>
        </Textblock>
      </PlaceObject>
    </Record>

    <Record element="planetlisting">
      <SetVariable variable="tableofcontents">
        <Value select="$tableofcontents"/>
        <Paragraph>
          <Value select="@name"/>
          <Value>, page </Value>
          <Value select="@page"/>
        </Paragraph>
      </SetVariable>
    </Record>

    <!-- Root element -->
    <Record element="planets">
      <SetVariable variable="column" select="2" />
      <LoadDataset name="toc"/>
      <SetVariable variable="Contents" select="''"/>
      <NewPage/>
      <ProcessNode select="planet"/>
    </Record>

    <Record element="planet">
      <SetVariable variable="Contents">
        <Value select="$Contents"/>
        <Element name="planetlisting">
          <Attribute name="name" select=" @name "/>
          <Attribute name="page" select=" sd:current-page()"/>
        </Element>
      </SetVariable>

      <ProcessNode select="url" />
      ...
      <NewPage />
      <SaveDataset filename="toc" elementname="tableofcontents" select="$Contents"/>
    </Record>

    <Record element="url">
      ...
    </Record>

Version: 3.2.0 | Start page | Element reference | Other language: German