Filter (Querier)

Filterable layers

Per default, layers are not filterable. If you wish to provide filter functionality for some layers, proceed as follows:

• For each layer you want to be filtrable create a functionality record with filterable_layers as name and the layer name as value.

• In any role (anonymous, registered, intranet or any other role) check the corresponding functionality records.

Note

Ngeo offers the filter functionality only for single layers, not for grouped layers.

Available attributes and operators in filters

All attributes defined as “exported” in the layer of your map server will be automatically available as filterable attribute. If the type, and so the operator on the attribute, is not adequate for filtering, you should adapt the type in your layer definition. See WFS GetFeature for more information (MapServer only).

Enumerate available attributes for a layer

Project Configuration file

In the filter panel, instead of the standard text field, it is possible to display combos providing the available values of the attributes. The values are automatically retrieved using a web service that does a SELECT distinct(<column>) FROM <table>.

The web service configuration is done in the vars.yaml file:

layers:
    enum:
        <layer_name>:
            dbsession: <session name>
            attributes:
                <attribute name>:
                    table: <[schema.]table name>
                    column_name: <column name>
                    separator: ","

dbsession: "<session name>" at the enum.defaults level can be used to specify another DB session than the main DB session. See Using multiple databases regarding the setup of multiple databases. If omitted, the main DB session is used.

table: "<[schema.]table name>" may be used at the layer defaults level as a the default table where following attributes may be found. It can be overridden at the attribute level. table is a mandatory parameter.

If column_name is not defined, the attribute name is used.

If separator is defined, the column is treated as a list of values.

Example:

layers
    enum:
        mapserver_layer:
            attributes:
                type: &layers-enum-mapserver-layer-defaults
                    table: geodata.table
                country: *layers-enum-mapserver-layer-defaults

Administration interface

You can add some additional configuration in the administration interface as follows.

It is possible to define enumerated or directed attributes, to WMS layers only, via metadata. The metadata to define is enumeratedAttributes or directedFilterAttributes.

For enumerated attributes, the value is a single string or a list of attributes (that we defined earlier in the vars.yaml file) separated with a comma.

For directed attributes, it is a single string or a list of attributes defined in the mapfile (columns and aliases from the selected table).

The difference is that enumerated attributes are configurable (like pointing to a specific database table), while directed attributes are ready-to-use values that come directly from the mapfile configuration.

Client-side documentation related to the enumeratedAttributes and directedFilterAttributes metadata is available here: gmfThemes.GmfMetaData.

Using DB sessions

It is possible to get attribute lists also for a layer whose data is hosted in an external database, using the dbsession: "<session name>" parameter.

See Using multiple databases for more information.