databasemetadata — Database Accessible Metadata

The databasemetadata file contains a generic metadata parser for data stored within a database

New in version 0.2.0.

class amg.databasemetadata.DbMetadata(dbname, uri, sql='SELECT geom FROM images LIMIT 1;')[source]

This class connects to a database using SQLAlchemy, uses the sql kwarg to execute a query that returns a geometry, loads the geometry into a shapely geometry, and finally returns a number of metadata properties.

Parameters

  • dbname (str) – The name of the database to connect to

  • uri (str) – The connection string in the form {databasetype}://{username}:{password}@{host}:{port}

  • sql (str) – The sql query to execute. This query should return a WKT Geometry

footprint

shapely Polygon or MultiPolygon

Type

obj

geometry

A dictionary containing geojson

Type

dict

bbox

Containing the four elements of the bounding box in the form (xmin, ymin, xmax, ymax)

Type

tuple

centroid

a shapely Point object defining the centroid of the footprint

Type

obj

Examples

>>> sql = '''
    WITH cte_geoms AS
        (
        SELECT id, geom FROM ctx
        WHERE
            ctx.name LIKE ANY (array ['B17_016091_2064_XN_26N031W%%', 'P17_007718_2022_XN_22N031W%%'])
        )
    SELECT ST_AsText(ST_Extent(ST_Intersection(A.geom, B.geom))) FROM cte_geoms as A, cte_geoms as B
    WHERE A.id > B.id AND A.id != B.id'''
>>> db = DbMetadata('dbname', 'postgresql://uname:pw@mydbrui.gov:port', sql=sql)
>>> db.footprint
class amg.databasemetadata.GenericSQLite(datafile, sql, column_remapper={})[source]

A generic interface to a SQLite database. This class expects to be passed an SQL query that returns a single row. The columns on the rows are named using introspection and the class data attribute is a dict where the keys are the column names and the rows are the column values. The column_remapper is used to homogenize the column names to the standard amg names.

Parameters

  • datafile (str) – The path to the sqlite database

  • sql (str) – An SQL query that returns a single row / record

  • column_remapper (dict) – Of DbName:amg_name. See the amg docs for standard property names