README

Quantum GIS (QGIS) Web Client
Installation  and Configuration Guide
Thursday May 22, 2014


Last Change : January 10, 2021


  1. For the terminally lazy
  2. Purpose
  3. Installation
  4. Configuration of Client
    4.1. Per Project Startup Options
    4.2. Configuration of search panels
    4.3. Configuration of the theme switcher
    4.4. Configuring of background layers
    4.5. Extending the interface
    4.6. Customize languages
  5. URL Rewriting
  6. Configuration of the search
    6.1. PHP Search
    6.2. WSGI Search
  7. License
  8. Developers and Contributors
  9. Acknowledgements


  1. For the terminally lazy
  ==========================

  sudo apt-get install apache2 libapache2-mod-fcgid
  cp apache-conf/qgis-web-client.conf.tmpl apache-conf/qgis-web-client.conf

Update the paths in the copied file then:

  cd /etc/apache2/sites-available/
  ln -s <path to apache-conf/qgis-web-client.conf> .
  sudo a2enmod rewrite
  sudo a2ensite qgis-web-client.conf
  sudo /etc/init.d/apache2 reload

1. Check the symlink in cgi-bin is correct.
2. Check the QGIS libs are in your /etc/ld.so.conf path
3. Copy site/index.xml and check paths match your system OR
  Modify index.html and point your browser to that


  2. Purpose
  ==========

A WMS based webgis client that makes use of QGIS specific WMS extensions (e.g.
highlighting, printing, metadata, etc.). QGIS webclient reads the configuration
from the WMS GetCapabilities command and builds the layer tree accordingly.
Supports legend graphic, feature info requests and printing.

The client builds on existing Web-GIS libraries OpenLayers and GeoExt, as well
as ExtJS 3 for the GUI widgets.

All major browsers should be supported.


  3. Installation
  ===============

Requirements (Server):

- Apache2 - Webserver (Ubuntu: apache2)
- mod-fcgid (Ubuntu: libapache2-mod-fcgid)
- QGIS and QGIS Server (best installed from source)

On ubuntu you can meet these requirements by simply doing:

  sudo apt-get install libapache2-mod-fcgid

The QGIS server compilation and installation will be covered in the QGIS manual.

For searching:

- python-wsgi for searching (Ubuntu: libapache2-mod-wsgi-py3)
- psycopg2 PostgreSQL db driver (Ubuntu: python3-psycopg2)
- webob - Python module providing WSGI request and response objects (Ubuntu:
  python3-webob)

The client part needs to be git cloned with the following command:
git clone https://github.com/qgis/qgis-web-client.git


  4. Configuration of Client
  ==========================

Global Settings for all projects (make a copy from one of the templates
provided):

  site/js/GlobalOptions.js

Translations (additional languages):

  site/js/Translations.js

Project settings and index:

  site/index.xml or site/index.html

Stylesheet of project index:

  site/gis-project_listing.xsl

Thumbnails for individual projects (if you take the index.xml route):

  thumbnails/projectname.png


  4.1. Per Project Startup Options
  ================================

These options are usually defined in the file site/index.xml. The stylesheet then generates
the startup URL parameter options. On the client, the file 'site/js/GetUrlParams.js'
is responsible for the proper handling of the startup options. The following options are available:

  lang

An optional language parameter. Normally, this parameter is defined in the file 'site/js/GlobalOptions.js'.
Optionally this can be overwritten on a per project base. Allowed values are two-character language codes
that must be present in the file 'site/js/Translations.js' or 'site/js/Translations_custom.js' if a custom tranlsations
file is used.

  visibleLayers

A comma-separated list of layers that should be set visible on the project start.

  visibleBackgroundLayer

Optionally the name of the background layer that should be set visible on project start. You must have background layers enabled in
GlobalOptions.js by setting enableBGMaps to true and a background layer must exist with this name. If either 
of these prerequisites is not met nothing happens and the parameter is simply ignored.

  format

This optional parameter allows a per project definition of the file format. Valid values are
'image/png', 'image/jpeg' and 'image/png;mode=8bit'. Defaults to 'image/png' if no format is given per project.
For correct specification of 'image/png;mode=8bit' in a URL please encode it correctly: 'image%2fpng%3b%20mode%3d8bit'.
If you specify this in site/js/GISProjectListing.js you do not need to encode it.

  fullColorLayers

An optional comma-separated list of layers that need to be in full color (24bit). This parameter is only
relevant if the project default image format is set to 'image/png' or 'image/png;mode=8bit'.
If any of the layers in the fullColorLayers parameter list is set visible, the format changes to 'image/jpeg'.

  maxExtent

The maximum extent of the project. This parameter is used if the 'Full View' navigation button is clicked.
If the 'startExtent' parameter is not specified, 'maxExtent' will also be used as the 'startExtent'.
The format is: left,bottom,right,top in map units.

  startExtent

The initial extent on project load if the project should start with a given, but not the maximum extent
(e.g. for zooming to a specific project area). Not to be confused with the 'maxExtent' parameter.
The format is: left,bottom,right,top in map units.

  searchtables

An optional list of additional search tables specific to the project. The format is 'schemaname.tablename'.
These additional search tables will be used for the search field at the top-right corner of the Webclient-GUI.
The default search tables are hard-coded in the file 'wsgi/search.wsgi', in the 'searchtables' array.


  4.2. Configuration of search panels
  ===================================

There are two types of search panels supported, using a direct WMS
GetFeatureInfo request or using URL rewriting with a much shorter search URL.

The search panels are configured in 'site/js/GlobalOptions.js'.

The following options are available:

  mapSearchPanelOutputRegion

SearchPanel search results output configuration (string), possible values:
default,right,bottom,popup
By default, search results will be shown in left panel, under the
search form. Sometimes this is not desired, here you can choose to
show the results in one of the other panels, like BottomPanel and
RightPanel. These additional panels are hidden by default because
their expansion and collapse trigger a map resize->reload cycle that
can slow down the application.
Example:

  var mapSearchPanelOutputRegion = 'popup';


    4.2.1. Using WMS GetFeatureInfo
    ===============================

  var simpleWmsSearch = {
    title: "Search continent",
    query: 'simpleWmsSearch',
    useWmsRequest: true,
    queryLayer: "Country",
    formItems: [
      {
        xtype: 'textfield',
        name: 'name',
        fieldLabel: "Name",
        allowBlank: false,
        blankText: "Please enter a name (e.g. 'africa')"
      }
    ],
    gridColumns: [
      {header: 'Name', dataIndex: 'name', menuDisabled: 'true'}
    ],
    selectionLayer: 'Country',
    selectionZoom: 0
  };

- title: title of the search tab
- query: identifier for this search
- useWmsRequest: enabled for WMS GetFeatureInfo request
- queryLayer: name of query layer
- formItems: list of Ext.form.FormPanel item configs
 - xtype: form field type
 - name: name of query layer attribute
 - fieldLabel: visible text for this field
 - blankText: popup text for blank fields
- gridColumns: list of Ext.grid.GridPanel column configs to show search
  results
- selectionLayer: name of layer for marking selected results (the same as
  queryLayer)
- selectionZoom: zoom level for jump-to when selecting results

Request URL:

When performing a search query using the above configuration,
the following get request will be made.

``http://localhost/wms/helloworld?SERVICE=WMS&VERSION=1.1.1&
REQUEST=GetFeatureInfo&LAYERS=Country&QUERY_LAYERS=Country&
FEATURE_COUNT=10&INFO_FORMAT=text/xml&SRS=EPSG:4326&
FILTER=Country:"name"+=+'africa'``


    4.2.2. Using URL Rewriting
    ==========================

For security and neatness, you may prefer to use rewritten URLs (so that your
internal server file paths are not revealed. In that case your options file
would contain something like this:

  var urlRewriteSearch = {
    title: "Search letter",
    query: 'samplesearch',
    formItems: [
      {
        xtype: 'hidden',
        name: 'query',
        value: 'samplesearch'
      },
      {
        xtype: 'textfield',
        name: 'colour',
        fieldLabel: "Colour",
        allowBlank: false,
        blankText: "Please enter a colour (e.g. 'orange')"
      }
    ],
    gridColumns: [
      {header: 'PKUID', dataIndex: 'pkuid', menuDisabled: 'true'},
      {header: 'Colour', dataIndex: 'colour', menuDisabled: 'true'}
    ],
    selectionLayer: 'Hello',
    selectionZoom: 1
  };

- title: title of the search tab
- query: identifier for this search
- formItems: list of Ext.form.FormPanel item configs, the query form
  field is required to match the rewrite rule (value is the same as query)
 - xtype: form field type
 - name: name of query layer attribute
 - fieldLabel: visible text for this field
 - blankText: popup text for blank fields
- gridColumns: list of Ext.grid.GridPanel column configs to show search
  results
- selectionLayer: name of layer for marking selected results
- selectionZoom: zoom level for jump-to when selecting results

For every search of this type you have to add a URL rewrite rule in the Apache
config. *Note:* Linebreaks added for formatting - they should be removed in your
config file.

  RewriteCond %{QUERY_STRING} ^(?:.*)query=samplesearch&*(?:.*)$
  RewriteCond %{QUERY_STRING} ^(?:(?:.*)&)?colour=([^&]*)(?:.*)$
  RewriteRule ^/wms/(.+)$ /cgi-bin/qgis_mapserv.fcgi?map=/
  <path-to-qgis-server-projects>/$1.qgs&SERVICE=WMS&VERSION=1.1.1&
  REQUEST=GetFeatureInfo&LAYERS=Hello&QUERY_LAYERS=Hello&FEATURE_COUNT=20&
  INFO_FORMAT=text/xml&SRS=EPSG:4326&FILTER=Hello:"colour"\ =\ '%1' [PT]


The first RewriteCond matches the query id of the search panel config. The
second RewriteCond extracts the values of the search request parameters.

The RewriteRule composes the actual WMS GetFeatureInfo request to QGIS mapserver.

Request URL:

http://localhost/wms/helloworld?query=samplesearch&colour=orange


    4.2.3. Add search panels to projects
    ====================================

In order for your search panel to appear in the web UI, you must
enumerate them in your GlobalOptions.js for example (with url rewriting):

  var mapSearchPanelConfigs = {
    "helloworld": [simpleWmsSearch, urlRewriteSearch]
  };

Example (no rewriting):

  var mapSearchPanelConfigs = {
    "../projects/helloworld.qgs": [simpleWmsSearch, urlRewriteSearch]
  };

Search panels are added to a project by adding a new key for the map name
with a list of search panel configs to mapSearchPanelConfigs.  If there is
no search panel configuration for a project, the search will be hidden in the
GUI.

The map name is whatever is passed in the get request for your .qgs file. For
example if your url includes this:

  http://localhost/cgi-bin/qgis_mapserv.fcgi?map=../projects/helloworld.qgs

then your mapSearchPanelConfigs should reflect ../projects/helloworld.qgs as
the key for the search list.


  4.3. Configuration of the theme switcher
  ========================================

The theme switcher allows to change to a diffent QGIS project (or map theme)
without having to leave the application and using the map extent. To
enable/disable the theme switcher you have to set the variable

  var mapThemeSwitcherActive = true;

in the site/js/GlobalOptions.js file to true|false. In addition you should
place thumbnail images of your map into the directory site/thumbnails where
the file name equals the projectname. All thumbnails should be 300x200 pixels
in size and in .png format. If you .qgs project is called 'helloworld.qgs' then
your thumbnail should be called 'helloworld.png'.

In addition you need to make entries for topics and projects in the file
'site/js/GISProjectListing.js'. Please use the given file as a template.
The file is in JSON format and starts with a few central parameters.


    4.3.1. Central theme switcher parameters
    ========================================

  path

The 'path' is the URL part used at the start of the application telling the QGIS Webclient where
to find the QGIS projects (see also Apache URL rewriting). This path
may be overwritten in some projects if you password-protect them in a separate Apache location.

  mapserver

This is the path to the WMS server used for WMS requests (e.g. for GetCapabilities, GetFeatureInfo, etc. requests).
Again, this parameter may be overwritten in some projects if you want to password-protect the WMS
in a separate Apache location.

  thumbnails

The URL where QGIS web client can find the project thumbnail images.

  title

The overall title of your Web-GIS. This will be later appended with the name
of your project, separated by a dash. It appears in the title bar of the browser
window and in the title bar of the web application.


    4.3.2. Per topic theme switcher parameters
    ==========================================

You can group your projects into topics. A topic only has a single parameter
with the name of the topic. In a topic element you can have several project
entries in a JSON array called project.

  name

The name of the topic.


    4.3.3. Per project theme switcher parameters
    ============================================

In a topic you can have several project entries. A project can overwrite the global
'path' and 'mapserver' entries.

  name

The name of the project or map. Will be displayed in the theme switcher below the thumbnail and
in the title strings of the application.

  path

Optional. Overrides the central settings in case you need to password-protect certain
projects. The 'path' is the URL part used at the start of the application telling the
QGIS Webclient where to find the QGIS projects (see also Apache URL rewriting).

  mapserver

Optional. Overrides the central settings in case you need to password-protect certain
projects. This is the path to the WMS server used for WMS requests (e.g. for GetCapabilities,
GetFeatureInfo, etc. requests).

  projectpath

The projectpath (directory) or part of the Apache rewrite expression necessary to find
the project file. This parameter is mandatory.

  projectfile

The QGIS project file or part of the Apache rewrite expression necessary to find
the project file. This parameter is mandatory. Depending on the Apache rewrite expression
you may have to omit the .qgis extension.

  format

Optional. The image format that QGIS web client should request. Valid values are: 'image/jpeg',
'image/png' or 'image/png;mode=8bit'. If omitted, the value is taken from site/js/GlobalOptions.js.
If it is not defined there either, the value defaults to 'image/png'.

  visibleLayers

Optional. A comma separated list of layers that should be visible after loading the projects.
A future QGIS Webclient version will also read the layer visibility directly from the GetProjectSettings
command.

  fullColorLayers

Optional. A comma separated list of layers that would trigger a format change from 'image/png' to 'image/jpeg'.
Per defaul, the project would use 'image/png' or 'image/png;mode=8bit' but if the user toggles the visibility
of a layer with orthophoto data or satellit images, the format will change to 'image/jpeg'.

  updateInterval

Optional. A prosa text indicating how often the project will get data update. E.g. daily, weekly,
monthly, weekly or occasional.

  lastUpdate

Optional. The date of the last data update, e.g. '2012-10-23'.

  responsible

Optional. The organization and/or person responsible for the project
and the data involved.

  startExtent

Optional. The bounding box (left,bottom,right,top in map units) used when starting the project.
If not specified, maxExtent or the extent from the GetProjectSettings is used.

  maxExtent

Optional. The maximum bounding box (left,bottom,right,top in map units) of the project.
If not specified the extent from the GetProjectSettings is used.

  showFeatureInfoLayerTitle

Optional. Boolean (true|false). Defines whether the layer title is displayed or not at the top
of the popup bubble displaying the feature info results. Influences both the hover and the click popups.

  tags

Optional. Tags or keywords displayed in the tooltips in the theme switcher.
The tags are also used in the search filter used in the theme switcher.


  4.4. Configuring of background layers
  =====================================

You can use any OpenLayers.Layer (http://dev.openlayers.org/releases/OpenLayers-2.13.1/doc/apidocs/files/OpenLayers/Layer-js.html) subclass as background layer. This layer must be added to baseLayers. You should do this in customBeforeMapInit() in Customizations.js. Example:

  // called before map initialization
  function customBeforeMapInit() {
      // define base layer
      var myBaseLayer = new OpenLayers.Layer.WMS("myBaseLayerName",
          "myBaseLayerWmsUrl", {
              layers: "myLayer",
              format: format,
              dpi: screenDpi,
              VERSION: "1.3.0"
          },
          {
              buffer:0,
              singleTile:true,
              ratio:1,
              transitionEffect:"resize",
              isBaseLayer: true, // important!
              projection:authid // requests the base layer in the projection defined in GlobalOptions
          }
      );
  
      // now add to baseLayers array
      baseLayers.push(myBaseLayer);
  }


  4.5. Extending the interface
  ============================

You can add buttons to implements additional functions (editing, advanced identify, etc.).
See the example in site/js/Customizations.js.


  4.6. Customize languages
  ========================

In order to provide shorter loading times you can reduce the languages in Translations.js to those you really need.
For this purpose the Python script site/js/build/translations.py is shipped with QGIS Web Client.

Write the languages you
need into site/js/build/translations.cfg and run the script, i.e. in a shell change to site/js/build and enter

  python translations.py

A new file site/js/Translations_custom.js is created. Copy this file to your server and adapt qgiswebclient.html accordingly.


  5. URL Rewriting
  ================

Using a standard installation of QGIS server, GlobalOptions.js will have a WMS
server configuration like

  var serverAndCGI = "/cgi-bin/qgis_mapserv.fcgi";

A sample URL for QGIS Web Client installed in /var/www/qgis-web-client:

  http://localhost/qgis-web-client/qgiswebclient.html?map=/opt/geodata/maps/NaturalEarth.qgs&visibleLayers=HYP_50M_SR_W

With the following rules for Apache mod_rewrite you can shorten the URLs to

  var serverAndCGI = "/wms";

and

  http://localhost/maps/NaturalEarth?visibleLayers=HYP_50M_SR_W

Rules in VirtualHost configuration:

  # Forbid direct access
  RewriteRule ^/cgi-bin/.*$ - [F]
  
  # Search with SearchPanel (e.g. Address)
  RewriteCond %{QUERY_STRING} ^(?:.*)query=address&*(?:.*)$
  RewriteCond %{QUERY_STRING} ^(?:(?:.*)&)?street=([^&]*)(?:(?:.*)&)+number=([^&]*)(?:.*)$
  RewriteRule ^/wms/(.+)$ /cgi-bin/qgis_mapserv.fcgi?map=/opt/geodata/maps/$1.qgs&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetFeatureInfo&LAYERS=addresses&QUERY_LAYERS=addresses&FEATURE_COUNT=10&INFO_FORMAT=text/xml&SRS=EPSG:21781&FILTER=addresses:"street"\ =\ '%1' AND "number"\ =\ %2 [PT]
  
  # Rewrite /wms/mapname to qgis_mapserv.fcgi?map=mappath/mapname.qgs
  RewriteRule ^/wms/(.+)$ /cgi-bin/qgis_mapserv.fcgi?map=/opt/geodata/maps/$1.qgs [QSA,PT]
  # Rewrite /maps/mapname to qgis-web-client main page. mapname will be extracted for wms calls in Javascript code.
  RewriteRule ^/maps/([^\.]+)$ /qgis-web-client/site/qgiswebclient.html [PT]
  # Rewrite /maps/* to qgis-web-client/site (e.g. /maps/gis_icons/mActionZoomNext.png -> /qgis-web-client/site/gis_icons/mActionZoomNext.png)
  RewriteRule ^/maps/(.*) /qgis-web-client/site/$1 [PT]

For supporting qgs files in subdirectories (e.g. /maps/subdir/mapnampe) replace last rule with:

  RewriteRule ^/maps/[^/]+/(.*) /qgis-web-client/site/$1 [PT]

For adding zones in different subdirecories (e.g. maps and maps-protected) add the following rules:

  RewriteRule ^/wms-protected/(.+)$ /cgi-bin/qgis_mapserv.fcgi?map=/opt/geodata/maps-protected/$1.qgs [QSA,PT]
  RewriteRule ^/maps-protected/([^\.]+)$ /qgis-web-client/site/qgiswebclient.html [PT]
  RewriteRule ^/maps-protected/(.*) /qgis-web-client/site/$1 [PT]


  6. Configuration of the search
  ==============================

Searching is handled by two separate scripts: "search" lists
back a hit list while the user is typing in the searchbox. It groups the
results and returns a bounding box of the result. "getSearchGeom" returns
the actual wkt geometry for a selected search result.

These scripts are provided in two flavors: PHP and WSGI (Python). 
The PHP version should run out-of-the-box
with just a few lines of configuration. There is no need to alter the DB
table structure in order to use PHP search scripts because all needed informations are read from
the project file. Another notable difference is that layer names are used instead of
table names, this is in order to not disclose internal DB details. The PHP scripts are available
under the php folder. 

The Python wsgi search scripts provide an advanced, more configurable and 
more detailed search solution. They draw their results directly from dedicated relations
in a PostGIS database. The WSGI scripts are available
under the wsgi folder. It is recommended to
install the wsgi scripts in a separate directory, e.g. /home/www/wsgi, a place
that is not reachable by regular web traffic.


  6.1. PHP Search
  ===============


    6.1.1. Available PHP scripts
    ============================


      6.1.1.1. Search
      ===============

The "search.php" scripts works as described above.
Accepted parameters:

- map (map name or path)
- query (search text)
- searchtables (optional: layer names to search in)

The companion is "search_geom.php".

- map (map name or path)
- searchtable (layer name)
- displaytext (the matched string)


      6.1.1.2. Unique list
      ====================

This simple script returns the unique values of a given column of a given PostgreSQL layer.
Accepted parameters:

- map (map name or path)
- layer (layer name)
- field (column name)

The script returns a json array of unique values and can be useful to implement select combo boxes for the search panels.


      6.1.1.3. Get legend
      ===================

This script has no wsgi counterpart, it works with recent QGIS Server versions (2.0.1 and newer) and can be used to build a template-based HTML legend instead of the image provided by GetLegendGraphic calls.

To use this feature you must activate it in GlobalOptions.js, search for the commented line below:

  var interactiveLegendGetLegendURL = '../php/get_legend.php?map=' + project_map + '&';

Legends generated by this script can be cached for speed, see the paragraph on configuration below.

Accepted parameters:

- map (map name or path)
- layer (layer name)


    6.1.2. PHP configuration file
    =============================

Configuration for the services is stored in  `config.php`.

Example:

  /****************************
   * Map rewrite configuration
   */
  // Prefix map name with path
  #define('MAP_PATH_REWRITE', '/home/xxx/public_html/QGIS-Web-Client/projects/');
  // Append .qgs to the map name
  #define('MAP_PATH_APPEND_QGS', true);
  
  
  /**************************************
   * search configuration
   */
  // Configuration for searchable layers
  $searchlayers_config = array(
      // Key is layer name
      'Country' => array(
          // SQL for text search: where to search
          'search_column' => 'name'
      )
  );
  
  // Default search tables
  define('DEFAULT_SEARCH_LAYERS', 'Country');
  // Limit search results
  define('SEARCH_LIMIT', 100);
  
  
  /**************************************
   *  Get legend configuration
   */
  // Cache expiry time in seconds 0=never cache
  define('GET_LEGEND_CACHE_EXPIRY', 60*60);
  // Cache directory, defaults to dirname(__FILE__) . '/legend_cache'
  define('GET_LEGEND_CACHE_DIRECTORY', null);
  // Defaults to current URL + '../cgi-bin/qgis_mapserv.fcgi?'
  define('WMS_ONLINE_RESOURCE', null);
  
  /* End configuration */

QGIS Web Client needs to know where to find the scripts, since most
configuration is read from the project file, this must be passed in the
query string, the file where this parameters are set is
GlobalOptions.js see the example below:

  // Adds project_map, read value from query string
  var project_map = Ext.urlDecode(window.location.search.substring(1)).map;
  
  var searchBoxQueryURL = '../php/search.php?map=' + project_map;
  var searchBoxGetGeomURL = '../php/search_geom.php?map=' + project_map;


    6.1.3. TODO
    ===========

Permalinks: the permalinks script is not yet implemented in PHP.


6.2. WSGI Search
  ================


6.2.1. Configuration of mod_wsgi for Python 3
    =========================================

You need to enable mod_wsgi as root. (Ubuntu: a2enmod wsgi).
If you get error module not exist, installation is missing (Ubuntu: apt-get install libapache2-mod-wsgi-py3)

Install also this:
(Ubuntu: apt-get install python3-webob python3-psycopg2)

You need to configure apache with the following lines (e.g. in file
``/etc/apache2/sites-available/default``):

::

  #mod_wsgi
  #Instead of WSGIScriptAlias which can reveal source code and connection details in browser, do this
  #WSGIScriptAlias /wsgi/ /var/www/html/gisapp/client/wsgi/
  Alias /wsgi/ /var/www/html/gisapp/client/wsgi/
  <Directory /var/www/html/gisapp/client/wsgi>
    SetHandler wsgi-script
    Options +ExecCGI
  </Directory>


6.2.2. Adaption of the wsgi scripts to your settings and needs
    ==============================================================


6.2.2.1. DB connection
      ======================

In the file ``qwc_connect.py`` please edit the first line containing the db connection string.

``DB_CONN_STRING="host='myhost' dbname='mydb' port='5432' user='myuser' password='secret'"``

This connection will be used in all wsgi scripts.

Adapt the parameters according to your server/db. It is highly recommended to
connect with a database user having limited rights only (e.g. select rights on relevant tables only).


6.2.2.2. Search type to be used
      ===============================

The search can use PostgreSQL's tsvector data type.
**"A tsvector value is a sorted list of distinct lexemes, which are words that have been normalized to
merge different variants of the same word."**
from the PostgreSQL doc (http://www.postgresql.org/docs/9.0/interactive/datatype-textsearch.html#DATATYPE-TSVECTOR).
Thus tsvector skips all the fill words and reduces nouns to their single form, a behaviour useful
for searching texts. However as we are normally dealing with place names here we want them to stay as they are.
If you use a language where the single form is a lot different from the plural form but your name contains a plural
you will not get a suitable result. If you want to use the tsvector search option you should activate the lines

::

  sql += "searchstring_tsvector @@ to_tsquery(\'not_your_language\', %s)"
  data += (querystrings[j]+":*",)

not_your_language is to be replaced with an entry e.g. finnish if you have German place names.
Thus plural forms and fillwords are kept as they are. Be aware of side effects!
Be sure to fill the field searchstring_tsvector with ``to_tsvector('not_your_language', 'yourstring')``.

The use of

::

  sql += "searchstring::tsvector @@ lower(%s)::tsquery"
  data += (querystrings[j]+":*",)

is discouraged as it does not find a place name like Stoke-sub-Hamden when you enter Stoke.

If you do not want to use tsvector at all you can enable the full string comparison on the field searchstring
(activated by default).

::

  sql += "searchstring ILIKE %s"
  data += ("%" + querystrings[j] + "%",)

This method however is slower than tsvector but not relevantly at least if you only have a couple 1000 datasets.


6.2.3. PostgreSQL table setup for searching
    ===========================================

Geometry must have set CRS code.
Check (must not return 0):
SELECT DISTINCT ST_Srid(geom) from [TABLE];

Set (example, table name: admin, geometry column: geom, CRS to set:4326):
SELECT UpdateGeometrySRID('admin', 'geom', 4326);

::

  CREATE TABLE cadastre.searchtable
  (
    searchstring text, --the search string (all lower case), e.g. "zürichstrasse 46, 8610 uster"
    displaytext text NOT NULL, --the display text for the search combobox, e.g. "Zürichstrasse 46, 8610 Uster (address)"
    search_category text, --should have a leading two digit number:, e.g.
                          --"03_parcels", where 03 is the order of the search categories, the number
                          --should be unique across all search tables
    the_geom geometry,    --the actual geometry
    searchstring_tsvector tsvector, -- be sure to fill this with to_tsvector()
    showlayer varchar(256), -- holds the layer name to be set visible if user chooses a respective result
    CONSTRAINT searchtable_pkey PRIMARY KEY (displaytext)
  )
  WITH (
    OIDS=FALSE
  );
  GRANT SELECT ON TABLE cadastre.searchtable TO qwc_user;

  -- Index: cadastre.in_cadastre_searchstring_tsvector_gin

  CREATE INDEX in_cadastre_searchstring_tsvector_gin
    ON cadastre.searchtable
    USING gin
    (searchstring_tsvector);

The above search table can also be a view or materialized view. One can combine
several search tables by specifying the ``searchtables=searchtable1,searchtable_n``
parameter when requesting the search.wsgi script. Any searchtable passed to ``search.wsgi``
may only contain the letters A to Z, a to z and the underscore. Double quoting the search
table throws an error, thus searchtables' names must contain lower characters only.

Using views is generally slower than properly indexed tables, check for yourself what works best.


  7. License
  ==========

The QGIS web client is released under a BSD license.

Copyright (2010-2012), The QGIS Project
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted
provided that the following conditions are met:

- Redistributions of source code must retain the above copyright notice, this list of conditions
  and the following disclaimer.
- Redistributions in binary form must reproduce the above copyright notice, this list of conditions
  and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
THE POSSIBILITY OF SUCH DAMAGE.


  8. Developers and Contributors
  ==============================

Developers:

- Jürgen Fischer
- Marco Hugentobler
- Pirmin Kalberer
- Andreas Neumann
- Alessandro Pasotti
- Niccolo Rigacci
- Denis Rouzaud
- Bernhard Ströbl
- Tim Sutton
- Mathias Walker

Translators:

- Giovanni Allegri
- Germán Carrillo
- Paolo Cavallini
- Diana Galindo
- Mayeul Kauffmann
- Samuel Mesa
- Alessandro Pasotti
- Nelson Silva
- Pavlo Taranov
- Tudor Bărăscu
- Uroš Preložnik


  9. Acknowledgements
  ===================

We'd like to thank the OpenLayers, GeoExt and ExtJS teams for providing their base libraries
we build upon.