Add initial search documentation for solr + fulltext search

Author: hka

src/images/add_solr_search_facet_permission.png

@@ -118,4 +118,145 @@ Note: The `qwc2-demo-app` (also used by the `qwc-map-viewer-demo` docker image)
 
 ## Configuring the fulltext search service <a name="fulltext-search"></a>
 
-For more information on the full-text search provider, see [qwc-fulltext-search-service](https://github.com/qwc-services/qwc-fulltext-search-service).
+### Solr configuration
+
+Before the fulltext search service can be configured,
+a new solr configuration file must be created.
+This file must be created in `volumes/solr/configsets/gdi/conf/`.
+The name of the file can be chosen freely.
+Here is an example XML file:
+
+```xml
+<dataConfig>
+    <dataSource
+        driver="org.postgresql.Driver"
+        url="jdbc:postgresql://{DB_HOST}:{DB_PORT}/{DB_NAME}"
+        user="{DB_USER}"
+        password="{DB_PASSWORD}"
+    />
+    <document>
+        <entity name="{SEARCH_NAME}" query="
+            WITH index_base AS (
+                /* ==== Base query for search index ==== */
+                SELECT
+                    '{SEARCH_NAME}'::text AS subclass,
+                    {PRIMARY_KEY} AS id_in_class,
+                    '{PRIMARY_KEY}' AS id_name,
+                    '{SEARCH_FIELD_DATA_TYPE}:n' AS id_type,
+                    {DISPLAYTEXT} AS displaytext,
+                    {SEARCH_FIELD_1} AS search_part_1,
+                    {GEOMETRY_FIELD} AS geom
+                FROM {SCHEMA}.{SEARCH_TABLE_NAME}
+                /* ===================================== */
+            )
+            SELECT
+                (array_to_json(array_append(ARRAY[subclass::text], id_in_class::text)))::text AS id,
+                displaytext AS display,
+                search_part_1 AS search_1_stem,
+                search_part_1 AS sort,
+                subclass AS facet,
+                'default' AS tenant,
+                (array_to_json(array_append(ARRAY[id_name::text], id_type::text)))::text AS idfield_meta,
+                (st_asgeojson(st_envelope(geom), 0, 1)::json -> 'bbox')::text AS bbox
+            FROM index_base">
+        </entity>
+    </document>
+</dataConfig>
+```
+
+The next table shows how the values, that are surrounded by {}, need to be defined.
+
+| **Name**                 | **Definition**                                                                    | **Example**      |
+|--------------------------|-----------------------------------------------------------------------------------|------------------|
+| `DB_HOST`                | Database hostname                                                                 | `qwc`postgis}    |
+| `DB_NAME`                | Database name                                                                     | `qwc_demo`       |
+| `DB_PORT`                | Database port number                                                              | `5432`           |
+| `DB_USER`                | Database username                                                                 | `qwc_service`    |
+| `DB_PASSWORD`            | Password for the specified database user                                          | `qwc_service`    |
+| `SEARCH_NAME`            | Name of the search                                                                | `fluesse_search` |
+| `PRIMARY_KEY`            | Primary key name of the table that is used in the search query                    | `ogc_fid`        |
+| `SEARCH_FIELD_DATA_TYPE` | Search field data type                                                            | `str`            |
+| `DISPLAYTEXT`            | Displaytext that will be shown by the QWC2 when a match was found                 | `name_long`      |
+| `SEARCH_FIELD_1`         | Table field that will be used by the search                                       | `name_long`      |
+| `GEOMETRY_FIELD`         | Name of the geometry column of the search table                                   | `wkb_geometry`   |
+| `SCHEMA`                 | Search table schema                                                               | `qwc_geodb`      |
+| `SEARCH_TABLE_NAME`      | Search table name                                                                 | `fluesse`        |
+
+*IMPORTANT*:
+In the case of several searches sharing the same database connection,
+all searche queries can be written to the same XML file. Each search
+corresponds to exactly one <entity> tag in the XML file.
+
+After the configuration file has been created, the search must be registered in `solr`.
+In the `volumes/solr/configsets/gdi/conf/solrconfig.xml` file you have to look for
+`<!-- SearchHandler` and add the following configuration
+
+```xml
+<requestHandler name="/SEARCH_NAME" class="solr.DataImportHandler">
+    <lst name="defaults">
+        <str name="config">NAME_OF_THE_CONFIGURATION_FILE.xml</str>
+    </lst>
+</requestHandler>
+```
+
+At last, the `solr` index has to be generated:
+
+```
+rm -rf volumes/solr/data/*
+docker compose restart qwc-solr
+curl 'http://localhost:8983/solr/gdi/SEARCH_NAME?command=full-import'
+```
+
+### Configure fulltext service
+
+The configuration of the fulltext search service can be found in `tenantConfig.json`.
+Search the `services` list for the JSON object that has `search` as its name.
+Then add a new facet to the facets list. An example entry could be:
+
+```json
+{
+    "name": "SEARCH_NAME",
+    "filter_word": "OPTIONAL_SEARCH_FILTER",
+    "table_name": "SCHEMA.SEARCH_TABLE_NAME",
+    "geometry_column": "GEOMETRY_FIELD",
+    "search_id_col": "PRIMARY_KEY"
+}
+```
+
+The `filter_word` field can be specified to activate / deactivate searches,
+if you have configure multiple searches for one map.
+Normally `filter_word` is left empty (`""`) which results in the search always
+being active.
+But if specified (e.g. `"house_no"` then the fulltext search will only use
+the configured search, if the user prefixes his search choise with "house_no:".
+
+### Activate search for a map
+
+In the last step, you only have to activate the search for a specific topic
+and give the users the necessary rights in the Admin GUI.
+
+1. Add the following to a theme item in the `themesConfig`:
+
+```json
+"searchProviders": [
+    {
+        "provider": "solr",
+        "default": [],
+        "layers": {
+            "QGIS_LAYER": "SEARCH_NAME"
+        }
+    }
+]
+```
+
+2. Create a new resource in the Admin GUI
+
+![Create resource](../images/create_solr_search_facet_resource.png?style=centerme)
+
+3. Add permissions on the newly created resource
+
+![Add permission](../images/add_solr_search_facet_permission.png?style=centerme)
+
+4. Re-generate the services configurations with the `Generate service configuration` button
+
+![Generate service configurations](../images/generate_service_configurations.png?style=centerme)