Full-text search¶

Enabling the full-text search feature involves adding a FullTextSearch plugin to the viewer, and creating and populating a dedicated table in the database.

The FullTextSearch plugin¶

The viewer should include a FullTextSearch plugin for the text search feature to be available in the user interface.

See the FullTextSearch API doc for the list of options the plugin can receive.

The main viewer includes a FullTextSearch plugin by default.

The full-text search table¶

The text search feature requires a dedicated PostgreSQL table. The full-text search table should be named tsearch (for text search) and should be in the application-specific schema.

You do not need to create the table yourself, as it is created by the create_db command line (see the section Install an existing application).

If you did want to create the table manually you would use the following commands:

sudo -u postgres psql -c "CREATE TABLE <schema_name>.tsearch (         id SERIAL PRIMARY KEY,         layer_name TEXT,         label TEXT,         public BOOLEAN DEFAULT 't',         params TEXT,         role_id INTEGER REFERENCES <schema_name>.role,         ts TSVECTOR);" <db_name>
sudo -u postgres psql -c "SELECT AddGeometryColumn('<schema_name>', 'tsearch', 'the_geom', <srid>, 'GEOMETRY', 2);" <db_name>
sudo -u postgres psql -c "CREATE INDEX tsearch_ts_idx ON <schema_name>.tsearch USING gin(ts);" <db_name>

with <schema_name>, <srid>, and <db_name> substituted as appropriate.

Also make sure that the db user can SELECT in the tsearch table:

sudo -u postgres psql -c 'GRANT SELECT ON TABLE <schema_name>.tsearch TO "<db_user>";' <db_name>

with <db_user>, and <db_name> substituded as appropriately.

Populate the full-text search table¶

Here is an example of an insertion in the tsearch table:

INSERT INTO app_schema.tsearch
  (the_geom, layer_name, label, public, role_id, ts)
VALUES
  (ST_GeomFromText('POINT(2660000 1140000)', 21781), 'Layer group',
   'text to display', 't', NULL,
   to_tsvector('french', regexp_replace('text to search', E'[\\[\\]\\(\\):&\\*]', ' ', 'g')));

Where Layer group is the name of the layer group that should be activated, text to display is the text that is displayed in the results, test to search is the text that we search for, french is the used language.

Here is another example where rows from a SELECT are inserted:

INSERT INTO app_schema.tsearch
  (the_geom, layer_name, label, public, role_id, ts)
SELECT
  geom, 'layer group name', text, 't', NULL,
  to_tsvector('german', regexp_replace(text, E'[\\[\\]\\(\\):&\\*]', ' ', 'g'))
FROM table;

Note

The language string used as the first argument to the to_tsvector function should match that defined in the default_locale_name variable of the application configuration (vars_<project>.yaml). For example if you have “french” text in the database the application’s default_locale_name should be fr. In other words c2cgeoportal assumes that the database language and the application’s default language match.

Populate with the themes¶

A script is available to fill the full-text search table, for more information type:

.build/venv/bin/theme2fts --help

Security¶

The tsearch table includes two security-related columns, namely public and role_id. If public is true then the row is available to any user, including anonymous users. And in that case, the role_id column is ignored by c2cgeoportal. If public is false then the row is not available to anonymous users. If role_id is NULL, the row is available to any authenticated user. If role_id is not NULL, the row is only available to users of the corresponding role.

Note

If you want to restrict some data to specific roles, then you will need to insert that data multiple times. For example, if you want to make the data of a table text-searchable, and restrict that data to the roles whose ids are 1 and 2 you will use two SQL INSERT statements:

INSERT INTO app_schema.tsearch
   (the_geom, layer_name, label, public, role_id, ts)
SELECT
   geom, 'layer group name', text, 'f', 1,
   to_tsvector('german', regexp_replace(text, E'[\\[\\]\\(\\):&\\*]', ' ', 'g'))
FROM table;

INSERT INTO app_schema.tsearch
   (the_geom, layer_name, label, public, role_id, ts)
SELECT
   geom, 'layer group name', text, 'f', 2,
   to_tsvector('german', regexp_replace(text, E'[\\[\\]\\(\\):&\\*]', ' ', 'g'))
FROM table;

Params¶

The params column can contain a JSON with a dictionary of parameters. For instance to specify a floor:

{
    "floor": "1"
}

Query string floor=1 is then automatically appended to all WMS requests.

See FloorSlider for more information.

Actions¶

The actions column contains a JSON with an array of actions like:

{
    "action": "add_layer",
    "data": "<the_layer_name>"
}

{
    "action": "add_group",
    "data": "<the_group_name>"
}

{
    "action": "add_theme",
    "data": "<the_theme_name>"
}

Example of SQL INSERT of actions data to add the layer “cadastre” on the map:

INSERT INTO app_schema.tsearch (..., actions)
VALUES (..., '[{"action": "add_layer", "data": "cadastre"}]')

Interface¶

If the interface_id column contains a value it means that the result is only for an interface.

Lang¶

If the lang column contains a value it means that the result is only for a language.

Configuration¶

In the configuration file vars_<project>.yaml you can add the following variables:

fulltextsearch_defaultlimit the default limit on the results, default is 30.
fulltextsearch_maxlimit the max possible limit, default is 200.

Ranking system¶

By default, the full-text search uses tsvector and ts_rank_cd to rank your search results (See: textsearch-controls. These methods are useful to handle language-based strings. That means for instance that plural nouns are the same as singular nouns. This system only checks if your search word exists in the result. That means that if you search B 12 Zug, B 120 Zug has the same weight because the system only see that the 12 exists in each case.

Alternatively you can use the similarity system of the pg_trgm module <https://www.postgresql.org/docs/9.0/static/pgtrgm.html>. This is based only on the similarities of words, without language analysis, and it cares only about how near is your search with the result. 12 is nearer to 12 than 120. To use this system, your request must contains the parameter rank_system=similarity and your database must have the pg_trgm extension:

CREATE EXTENSION pg_trgm;

Using the unaccent extension¶

By the default the full-text search is accent-sensitive. To make it accent-insensitive Postgres’s unaccent extension can be used.

First connect to the database:

sudo -u postgres psql -d <database>

For that we need the Postgres unaccent extension and dictionary:

CREATE EXTENSION unaccent;

Insert the unaccent dictionary into a text search configuration (Documentation):

CREATE TEXT SEARCH CONFIGURATION fr (COPY = french);
ALTER TEXT SEARCH CONFIGURATION fr
    ALTER MAPPING FOR hword, hword_part, word
    WITH unaccent, french_stem;

When populating the tsearch table use the text configuration ‘fr’ instead of ‘french’. For example:

INSERT INTO <schema>.tsearch
  (the_geom, layer_name, label, public, role_id, ts)
VALUES
  (ST_GeomFromText('POINT(2660000 1140000)', 21781), 'Layer group',
   'Accent text to display (éàè)', 't', NULL, to_tsvector('fr', 'Accent text to search (éàè)'));

And define the configuration in the vars_<project>.yaml file:

fulltextsearch:
    languages:
        fr: fr

fr: fr is a link between the pyramid language and the text search configuration, by default the it is fr: french because the default french text search configuration is named ‘french’.