# Metadata-DB-linker The purpose of this QGIS plugin is to make it possible to enter metadatainformation (name, description, etc.) for a table in a database through the plugin interface or through DB-manager.

Installation and setup

The MetadataDBLinker plugin requires as minimum one table where metadata is stored, and an optional table describing the fields in the graphical user interface. The plugin can be installed using the install plugin from zip option in QGIS. ZIP files can be found and downloaded under releases for this Github Repository.

First time setup

First time setting up the plugin the metadata table should be created and settings filled out accordingly. Navigate to the settings window in QGIS Settings -> Options and MetadataDBLinker will have its own tab.

MetadataDBLinker allows a dedicated user to be used with the metadata table. Access rights to this user can be controlled in PostgreSQL. Click the Metadata Table (SQL) button for an SQL CREATE statement that will create the table. Create the table in your PostgreSQL Database, make sure your user has approriate access to it then fill out the settings. Finally test the connection by clicking the test button, if OK the plugin should be working. The SQL statement is also found in this repository under ./sql/metadata_table.sql.

Gui Table

An extra table can optionally be configured to describe if certain GUI fields in the dialog should be required or enabled. The Save metadata button will be greyed out if required fields are not filled. Click the Gui Table (SQL) button in the settings for an SQL CREATE statement to set up this table. The SQL statement is also found in this repository under ./sql/gui_table.sql.

Rows in this table refers columns in the metadata table by the metadata_col_name column. gui_table has the following columns and attributes:

• metadata_col_name: Acts as a foreign key on the metadata table, the column must exist in the metadata table to have an effect.
• required: If the field is considered required. If a field is required it has to be filled out.
• editable: If the field can be edited, if false the field can not be edited, but can still be seen
• extra_field: If the field is considered an additional field.
• is_shown: If false and the field is an extra_field, the field will not be shown in the gui. Static fields, can not be hidden.
• display_name: If the field is an extra_field, display_name controls the label for the field. Static fields, can not have their display_name changed
• type: If the field is an extra_field, type controls the field type. Accepted values are: ["text","multiline","datetime","boolean"].
  • text: a single-line text field
  • multiline: a larger multi-line text field
  • datetime: A datetime field
  • boolean: A checkmark that evaluates to either true or false

Both tables should be in the same schema. A typical setup would look like:

📦 metadata (schema)
┣ 🗄️ metadata (table)
┃ ┣ 📜 guid ([PK] character varying)
┃ ┣ 📜 name (character varying)
┃ ┣ 📜 description (character varying)
┃ ┣ 📜 kle_no (character varying)
┃ ┣ 📜 responsible (character varying)
┃ ┣ 📜 project (character varying)
┃ ┣ 📜 host (character varying)
┃ ┣ 📜 db (character varying)
┃ ┣ 📜 port (character varying)
┃ ┣ 📜 schema (character varying)
┃ ┣ 📜 sourcetable (character varying)
┃ ┣ 📜 ts_timezone (character varying)
┃ ┣ 📜 geodatainfo_link (character varying)
┃ ┣ 📜 ... (additional fields)
┣ 🗄️ gui-table (table)
┃ ┣ 📜 id (integer)
┃ ┣ 📜 metadata_col_name ([PK] character varying)
┃ ┣ 📜 type (character varying)
┃ ┣ 📜 required (boolean)
┃ ┣ 📜 editable (boolean)
┃ ┣ 📜 is_shown (boolean)
┃ ┣ 📜 displayname (character varying)
┃ ┣ 📜 extra_field (bool)

Look at the sql folder for complete CREATE TABLE statements

Usage

The plugin can be accessed in two ways. If the plugin is configured and active it can be reached from the toolbar. The plugin will also automatically start after importing layers into DB-manager. Click a layer in the browser within plugin to assign metadata, or if the dialog was started from DB-manager the layer is already selected. Fill out the metadata accordingly and hit Save metadata when done. The metadata fields will be enabled when a layer is selected in the browser. If a layer already has metadata assigned these fields will be filled and can be updated.

Locator

As an added feature, layers with added metadata can be searched using the QGIS Locator by their metadata fields under the category "Metadata-DB-Linker". Clicking the entries will add to them to the current active project.