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Template-Driven Output

Author:Chris Hodgson
Contact:chodgson at refractions.net
Last Updated:13-04-2011

Introduction

RFC 36 added support for defining template-driven OUTPUTFORMATs for use with feature queries, including WMS GetFeatureInfo and WFS GetFeature. This allows for custom text-oriented output such as GeoJSON, KML, or XML. The templates are essentially the same as with the standard MapServer query Templating, however there are some additional tags to allow for template definition in a single file instead of the standard header/template/footer.

Note

There are other, simpler, ways to output some of these formats using MapServer. However, template-driven output provides maximal flexibility and customization of the output, at the cost of additional complexity and configuration.

Note

In order for template-driven output to work, layers that are to be output need to have the TEMPLATE key word included:

TEMPLATE "dummy"

Note

In order for template-driven output to work through WFS, the format needs to be listed in wfs_getfeature_formatlist in the WEB METATDATA section or the LAYER METATDATA section (the geojson format from the example below):

"wfs_getfeature_formatlist" "gml,geojson"

OUTPUTFORMAT Declarations

Details of template-driven output formats are controlled by an OUTPUTFORMAT declaration. The declarations define the template file to be used, as well as other standard OUTPUTFORMAT options.

Exemples :

OUTPUTFORMAT
  NAME "kayml"
  DRIVER "TEMPLATE"
  MIMETYPE "application/vnd.google-earth.kml+xml"
  FORMATOPTION "FILE=myTemplate.kml"
  FORMATOPTION "ATTACHMENT=queryResults.kml"
END

OUTPUTFORMAT
  NAME "geojson"
  DRIVER "TEMPLATE"
  FORMATOPTION "FILE=myTemplate.js"
END

OUTPUTFORMAT
  NAME "customxml"
  DRIVER "TEMPLATE"
  FORMATOPTION "FILE=myTemplate.xml"
END

The template file to be used is determined by the “FILE=...” FORMATOPTION. The template filename is relative to the mapfile’s path. As is standard with MapServer template files, the file must containt the magic string ‘mapserver template’ in the first line of the file, usually within a comment, but this line is not output to the client.

Note

Valid suffixes for the template file are: .xml, .wml, .html, .htm, .svg, .kml, .gml, .js, .tmpl.

The MIMETYPE and FORMATOPTION “ATTACHMENT=...” parameters are very useful for controlling how a web browser handles the output file.

Template Substitution Tags

These tags only work in query result templates, and their purpose is primarily to simplify the templating to a single file for custom ouput formats.

[include src=”otherTemplate.txt”]

Includes another template file; the path to the template file is relative to the mapfile path.

Attributes:

  • src: The file to be included.
[resultset layer=layername]...[/resultset]

Defines the location of the results for a given layer.

Attributes:

  • layer: The layer to be used
  • nodata: (optional) A string to return if no results are returned.
[feature]...[/feature]

Defines the loop around the features returned for a given layer.

Attributes:

  • limit: (optional) Specifies the maximum number of features to output for this layer.
  • trimlast: (optional) Specifies a string to be trimmed off of the end of the final feature that is output. This is intended to allow for trailing record delimiters to be removed. See the examples below.
[join name=join1]...[/join]
defines the loop around the features join from another layer.

Voir aussi

Templating

Exemples

This example shows how to emulate the old 3-file system using the new system, to compare the usage:

<!-- mapserver template -->
[include src="templates/header.html"]
[resultset layer=lakes]
  ... old layer HEADER stuff goes here, if a layer has no results
      this block disappears...
  [feature]
    ...repeat this block for each feature in the result set...
    [join name=join1]
      ...repeat this block for each joined row...
    [/join]
  [/feature]
  ...old layer FOOTER stuff goes here...
[/resultset]
[resulset layer=streams]
  ... old layer HEADER stuff goes here, if a layer has no results
      this block disappears...
  [feature]
    ...repeat this block for each feature in the result set...
  [/feature]
  ...old layer FOOTER stuff goes here...
[/resultset]
[include src="templates/footer.html"]

A specific GML3 example:

<!-- mapserver template -->
<?xml version="1.0" encoding="ISO-8859-1"?>
[resultset layer=mums]
<MapServerUserMeetings xmlns="http://localhost/ms_ogc_workshop"
    xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:gml="http://www.opengis.net/gml"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://localhost/ms_ogc_workshop ./mums.xsd">
 <gml:description>This is a GML document which provides locations of
    all MapServer User Meeting that have taken place</gml:description>
 <gml:name>MapServer User Meetings</gml:name>
 <gml:boundedBy>
  <gml:Envelope>
   <gml:coordinates>-93.093055556,44.944444444 -75.7,45.4166667</gml:coordinates>
  </gml:Envelope>
 </gml:boundedBy>
 [feature]
 <gml:featureMember>
  <Meeting>
   <gml:description>[desc]</gml:description>
   <gml:name>[name]</gml:name>
   <gml:location>
    <gml:Point srsName="http://www.opengis.net/gml/srs/epsg.xml#4326">
     <gml:pos>[x] [y]</gml:pos>
    </gml:Point>
   </gml:location>
   <year>[year]</year>
   <venue>[venue]</venue>
   <website>[url]</website>
  </Meeting>
 </gml:featureMember>
 [/feature]
 <dateCreated>2007-08-13T17:17:32Z</dateCreated>
</MapServerUserMeetings>
[resultset]

Un exemple GeoJSON.

Could be called using ...&layer=mums&mode=nquery&qformat=geojson

Or by adding &outputformat=geojson to a WFS getfeature request:

// mapserver template
[resultset layer=mums]
{
  "type": "FeatureCollection",
  "features": [
    [feature trimlast=","]
    {
      "type": "Feature",
      "id": "[myuniqueid]",
      "geometry": {
        "type": "PointLineString",
        "coordinates": [
          {
            "type": "Point",
            "coordinates": [[x], [y]]
          }
        ]
      },
      "properties": {
        "description": "[description]",
        "venue": "[venue]",
        "year": "[year]"
      }
    },
    [/feature]
  ]
}
[/resultset]

A more complicated KML example. Note the use of [shpxy] to support multipolygons with holes, and also that a point placemark is included with each feature using [shplabel]:

<!--MapServer Template-->
<?xml version="1.0" encoding="UTF-8"?>
<kml xmlns="http://www.opengis.net/kml/2.2"
     xmlns:gx="http://www.google.com/kml/ext/2.2"
     xmlns:kml="http://www.opengis.net/kml/2.2"
     xmlns:atom="http://www.w3.org/2005/Atom">
<Document>
  <Style id="parks_highlight">
    <IconStyle>
      <scale>1.4</scale>
      <Icon>
        <href>http://maps.google.com/mapfiles/kml/shapes/parks.png</href>
      </Icon>
      <hotSpot x="0.5" y="0" xunits="fraction" yunits="fraction"/>
    </IconStyle>
    <LineStyle>
      <color>ffff5500</color>
      <width>4.2</width>
    </LineStyle>
    <PolyStyle>
      <color>aaaaaaaa</color>
    </PolyStyle>
    <BalloonStyle>
      <text>
        <![CDATA[
          <p ALIGN="center"><b>$[name]</b></p>
          $[description]
        ]]>
      </text>
    </BalloonStyle>
  </Style>
  <Style id="parks_normal">
    <IconStyle>
      <scale>1.2</scale>
      <Icon>
        <href>http://maps.google.com/mapfiles/kml/shapes/parks.png</href>
      </Icon>
      <hotSpot x="0.5" y="0" xunits="fraction" yunits="fraction"/>
    </IconStyle>
    <LineStyle>
      <color>ffff5500</color>
      <width>4.2</width>
    </LineStyle>
    <PolyStyle>
      <color>ff7fff55</color>
    </PolyStyle>
    <BalloonStyle>
      <text>
        <![CDATA[
          <p ALIGN="center"><b>$[name]</b></p>
          $[description]
        ]]>
      </text>
    </BalloonStyle>
  </Style>
  <StyleMap id="parks_map">
    <Pair>
      <key>normal</key>
      <styleUrl>#parks_normal</styleUrl>
    </Pair>
    <Pair>
      <key>highlight</key>
      <styleUrl>#parks_highlight</styleUrl>
    </Pair>
  </StyleMap>
[resultset layer=parks]
  <Folder>
    <name>Parks</name>
[feature trimlast="," limit=1]
    <Placemark>
      <name>[NAME]</name>
      <Snippet/>
      <description>
        <![CDATA[
          <p>Year Established: [YEAR_ESTABLISHED]</p>
          <p>Area: [AREA_KILOMETERS_SQUARED] sq km</p>
        ]]>
      </description>
      <styleUrl>#parks_map</styleUrl>
      <ExtendedData>
        <Data name="Year Established">[YEAR_ESTABLISHED]</Data>
        <Data name="Area">[AREA_KILOMETERS_SQUARED]</Data>
      </ExtendedData>
      <MultiGeometry>
        <Point>
          <coordinates>[shplabel proj=epsg:4326 precision=10],0</coordinates>
        </Point>
[shpxy     ph="<Polygon><tessellate>1</tessellate>" pf="</Polygon>"
           xf="," xh=" " yh=" " yf=",0 "
           orh="<outerBoundaryIs><LinearRing><coordinates>"
           orf="</coordinates></LinearRing></outerBoundaryIs>"
           irh="<innerBoundaryIs><LinearRing><coordinates>"
           irf="</coordinates></LinearRing></innerBoundaryIs>"
           proj=epsg:4326 precision=10]
      </MultiGeometry>
    </Placemark>
[/feature]
  </Folder>
[/resultset]
</Document>
</kml>

Warning

For templates (Templating), there are a number of reserved words. If you have want to expose an attribute with a name that is equal to a reserved word, you can not use the shorthand [attribute_name], but will have to use construct [item name=attribute_name] instead. For example, in a template, [id] is a system generated unique session id (see Templating). So if you have an attribute named “id” that you want to expose, you will either have to rename it or use the construct [item name=id].

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