Thuban/Model/postgisdb.py

# Copyright (C) 2003 by Intevation GmbH
# Authors:
# Martin Mueller <[email protected]>
# Bernhard Herzog <[email protected]>
#
# This program is free software under the GPL (>=v2)
# Read the file COPYING coming with the software for details.

"""Basic interface to a PostGIS database"""

from __future__ import generators

try:
    import psycopg
except ImportError:
    psycopg = None

import table
import wellknowntext

from data import SHAPETYPE_POLYGON, SHAPETYPE_ARC, SHAPETYPE_POINT, RAW_WKT

def has_postgis_support():
    """Return whether this Thuban instance supports PostGIS connections

    Having PostGIS support means that the psycopg module can be
    imported.
    """
    return psycopg is not None

def psycopg_version():
    return psycopg.__version__

if psycopg is not None:
    type_map = [(psycopg.STRING, table.FIELDTYPE_STRING),
                (psycopg.INTEGER, table.FIELDTYPE_INT),
                (psycopg.FLOAT, table.FIELDTYPE_DOUBLE)]


class ConnectionError(Exception):

    """Class for exceptions occurring when establishing a Databse connection"""


class PostGISConnection:

    """Represent a PostGIS database

    A PostGISConnection instance has the following public attributes:

    dbname -- The name of the database
    host, port -- Host and port to connect to
    user -- The user name to connect as.

    All of these attributes are strings and may be empty strings to
    indicate default values.
    """

    def __init__(self, dbname, host="", user="", password="", dbtype="",
                 port=""):
        self.dbname = dbname
        self.host = host
        self.port = port
        self.user = user
        self.password = password
        self.dbtype = dbtype
        self.connect()

    def connect(self):
        """Internal: Establish the database connection"""
        params = []
        for name in ("host", "port", "dbname", "user", "password"):
            val = getattr(self, name)
            if val:
                params.append("%s=%s" % (name, val))
        try:
            self.connection = psycopg.connect(" ".join(params))
        except psycopg.OperationalError, val:
            raise ConnectionError(str(val))

        # determine the OID for the geometry type. This is PostGIS
        # specific.
        cursor = self.connection.cursor()
        cursor.execute("SELECT OID, typname FROM pg_type WHERE"
                       +" typname = 'geometry'")
        row = cursor.fetchone()
        self.connection.commit()
        if row is not None:
            self.geometry_type = row[0]
        else:
            raise ValueError("Can't determine postgres type of geometries")

    def BriefDescription(self):
        """Return a brief, one-line description of the connection

        The return value is suitable for a list box of all database
        connections.
        """
        return ("postgis://%(user)s@%(host)s:%(port)s/%(dbname)s"
                % self.__dict__)

    def Close(self):
        """Close the database connection"""
        self.connection.close()

    def GeometryTables(self):
        """Return a list with the names of all tables with a geometry column"""
        cursor = self.connection.cursor()
        cursor.execute("SELECT f_table_name FROM geometry_columns;")
        result = [row[0] for row in cursor.fetchall()]
        self.connection.commit()
        return result

    def cursor(self):
        """Return a DB API 2.0 cursor for the database"""
        return self.connection.cursor()


class PostGISColumn:

    """Column description for a PostGISTable"""

    def __init__(self, name, type, index):
        self.name = name
        self.type = type
        self.index = index


class PostGISTable:

    """A Table in a PostGIS database"""

    def __init__(self, db, tablename):
        """Initialize the PostGISTable.

        The db parameter should be an instance of PostGISConnection and
        tablename the name of a table in the database represented by db.
        """
        self.db = db
        self.tablename = tablename
        self.column_map = {}
        self._fetch_table_information()

    def _fetch_table_information(self):
        """Internal: Update information about the table"""
        self.columns = []
        cursor = self.db.cursor()
        cursor.execute("SELECT * FROM %s WHERE 0=1" % self.tablename)
        description = cursor.description

        for i in range(len(description)):
            for pgtyp, tabletyp in type_map:
                if pgtyp == description[i][1]:
                    col = PostGISColumn(description[i][0], tabletyp, i)
                    break
            else:
                if description[i][1] == self.db.geometry_type:
                    self.geometry_column = description[i][0]
                # No matching table type. Ignore the column.
                # FIXME: We should at least print a warning about
                # ignored columns
                continue
            self.columns.append(col)

        for col in self.columns:
            self.column_map[col.name] = col
            self.column_map[col.index] = col

        # Build query string for ReadRowAsDict
        self.query_stmt = ("SELECT %s from %s"
                           % (", ".join([col.name for col in self.columns]),
                              self.tablename))

    def DBConnection(self):
        """Return the dbconnection used by the table"""
        return self.db

    def TableName(self):
        """Return the name of the table in the database"""
        return self.tablename

    def Dependencies(self):
        """Return an empty tuple because a PostGISTable depends on nothing else
        """
        return ()

    def NumColumns(self):
        return len(self.columns)

    def Columns(self):
        return self.columns

    def Column(self, col):
        return self.column_map[col]

    def HasColumn(self, col):
        return self.column_map.has_key(col)

    def NumRows(self):
        cursor = self.db.cursor()
        cursor.execute("SELECT count(*) FROM %s" % self.tablename)
        return cursor.fetchone()[0]

    def ReadRowAsDict(self, row):
        cursor = self.db.cursor()
        cursor.execute(self.query_stmt + " LIMIT 1 OFFSET %d" % row)
        result = {}
        for col, value in zip(self.columns, cursor.fetchone()):
            result[col.name] = value
        return result

    def ReadValue(self, row, col):
        cursor = self.db.cursor()
        cursor.execute("SELECT %s FROM %s LIMIT 1 OFFSET %d" %
                       (self.column_map[col].name, self.tablename, row))
        return cursor.fetchone()[0]

    def ValueRange(self, col):
        cursor = self.db.cursor()
        name = self.column_map[col].name
        cursor.execute("SELECT min(%s), max(%s) FROM %s" %
                       (name, name, self.tablename))
        return tuple(cursor.fetchone())

    def UniqueValues(self, col):
        cursor = self.db.cursor()
        name = self.column_map[col].name
        cursor.execute("SELECT %s FROM %s GROUP BY %s" %
                       (name, self.tablename, name))
        return [row[0] for row in cursor.fetchall()]

    def SimpleQuery(self, left, comparison, right):
        if comparison not in ("==", "!=", "<", "<=", ">=", ">"):
            raise ValueError("Comparison operator %r not allowed" % comparison)

        if comparison == "==":
            comparison = "="

        if isinstance(right, PostGISColumn):
            right_template = right.name
            params = ()
        else:
            right_template = "%s"
            params = (right,)

        query = "SELECT gid FROM %s WHERE %s %s %s ORDER BY gid;" \
                % (self.tablename, left.name, comparison, right_template)

        cursor = self.db.cursor()
        cursor.execute(query, params)
        result = []
        while 1:
            row = cursor.fetchone()
            if row is None:
                break
            result.append(row[0])
        return result


class PostGISShape:

    def __init__(self, shapeid, data):
        self.shapeid = shapeid
        self.data = data

    def compute_bbox(self):
        """
        Return the bounding box of the shape as a tuple (minx,miny,maxx,maxy)
        """
        xs = []
        ys = []
        for part in self.Points():
            for x, y in part:
                xs.append(x)
                ys.append(y)
        return (min(xs), min(ys), max(xs), max(ys))

    def ShapeID(self):
        return self.shapeid

    def Points(self):
        return wellknowntext.parse_wkt_thuban(self.data)

    def RawData(self):
        return self.data


shapetype_map = {"POLYGON": SHAPETYPE_POLYGON,
                 "MULTILINESTRING": SHAPETYPE_ARC,
                 "POINT": SHAPETYPE_POINT}


class PostGISShapeStore(PostGISTable):

    """Shapestore interface to a table in a PostGIS database"""

    def Table(self):
        """Return self since a PostGISShapeStore is its own table."""
        return self

    def OrigShapeStore(self):
        """Return None since the PostGISShapeStore is not derived from another
        """
        return None

    def ShapeType(self):
        """Return the type of the shapes in the shapestore."""
        cursor = self.db.cursor()
        cursor.execute("SELECT type FROM geometry_columns WHERE"
                       " f_table_name=%s", (self.tablename,))
        result = cursor.fetchone()[0]
        cursor.close()
        return shapetype_map[result]

    def RawShapeFormat(self):
        """Return the raw data format of the shape data.

        For the PostGISShapeStore this is RAW_WKT.
        """
        return RAW_WKT

    def NumShapes(self):
        # The number of shapes is the same as the number of rows,
        # assuming that the geometry can't be NULL.
        return self.NumRows()

    def BoundingBox(self):
        """Return the bounding box of all shapes in the postgis table"""
        minx = miny = maxx = maxy = None
        x=[]
        y=[]
        cursor = self.db.cursor()
        try:
            stmt = ("SELECT AsText(Envelope(%s)) FROM %s;"
                    % (self.geometry_column, self.tablename))
            cursor.execute(stmt)
            result = cursor.fetchone()
            while result:
                result = result[0]
                # Here we must do some parsing through the result string
                # to get the points out of the polygon which representes
                # the bounding box The first and the last point of a
                # polygon are identical
                result = result.split("(")[2]
                result = result.split(")")[0]
                points = result.split(",")
                del points[4] # Remove the last point
                for point in points:
                    px, py = point.split()
                    x.append(float(px))
                    y.append(float(py))
                result = cursor.fetchone()
        finally:
            cursor.close()
        if not x:
            # Empty table
            return None
        return (min(x), min(y), max(x), max(y))

    def Shape(self, shapeid):
        cursor = self.db.cursor()
        cursor.execute("SELECT AsText(%s) FROM %s WHERE gid=%d"
                       % (self.geometry_column, self.tablename, shapeid))
        wkt = cursor.fetchone()[0]
        cursor.close()
        return PostGISShape(shapeid, wkt)

    def ShapesInRegion(self, bbox):
        """Generate all shapes overlapping the region given by bbox."""
        # IMPORTANT:This will work for PostGIS < 0.8
        left, bottom, right, top = bbox
        geom = (("POLYGON((" + ", ".join(["%f %f"] * 5) + "))")
                % (left, bottom, left, top, right, top, right, bottom,
                   left, bottom))
        cursor = self.db.cursor()
        cursor.execute("SELECT gid, AsText(%s) FROM %s"
                     " WHERE %s && GeometryFromText('%s', -1) ORDER BY gid"
                       % (self.geometry_column, self.tablename,
                          self.geometry_column, geom))
        while 1:
            result = cursor.fetchone()
            if result is None:
                raise StopIteration
            yield PostGISShape(result[0], result[1])
1	bh	1605	# Copyright (C) 2003 by Intevation GmbH
2			# Authors:
3			# Martin Mueller <[email protected]>
4			# Bernhard Herzog <[email protected]>
5			#
6			# This program is free software under the GPL (>=v2)
7			# Read the file COPYING coming with the software for details.
8
9			"""Basic interface to a PostGIS database"""
10
11			from __future__ import generators
12
13			try:
14			import psycopg
15			except ImportError:
16			psycopg = None
17
18			import table
19			import wellknowntext
20
21			from data import SHAPETYPE_POLYGON, SHAPETYPE_ARC, SHAPETYPE_POINT, RAW_WKT
22
23	bh	1625	def has_postgis_support():
24			"""Return whether this Thuban instance supports PostGIS connections
25	bh	1605
26	bh	1625	Having PostGIS support means that the psycopg module can be
27			imported.
28			"""
29			return psycopg is not None
30
31	bh	1631	def psycopg_version():
32			return psycopg.__version__
33
34	bh	1605	if psycopg is not None:
35			type_map = [(psycopg.STRING, table.FIELDTYPE_STRING),
36			(psycopg.INTEGER, table.FIELDTYPE_INT),
37			(psycopg.FLOAT, table.FIELDTYPE_DOUBLE)]
38
39	bh	1636
40			class ConnectionError(Exception):
41
42			"""Class for exceptions occurring when establishing a Databse connection"""
43
44
45	bh	1605	class PostGISConnection:
46
47			"""Represent a PostGIS database
48
49			A PostGISConnection instance has the following public attributes:
50
51			dbname -- The name of the database
52			host, port -- Host and port to connect to
53			user -- The user name to connect as.
54
55			All of these attributes are strings and may be empty strings to
56			indicate default values.
57			"""
58
59			def __init__(self, dbname, host="", user="", password="", dbtype="",
60			port=""):
61			self.dbname = dbname
62			self.host = host
63			self.port = port
64			self.user = user
65			self.password = password
66			self.dbtype = dbtype
67	bh	1620	self.connect()
68
69			def connect(self):
70			"""Internal: Establish the database connection"""
71	bh	1605	params = []
72			for name in ("host", "port", "dbname", "user", "password"):
73			val = getattr(self, name)
74			if val:
75			params.append("%s=%s" % (name, val))
76	bh	1636	try:
77			self.connection = psycopg.connect(" ".join(params))
78			except psycopg.OperationalError, val:
79			raise ConnectionError(str(val))
80	bh	1605
81			# determine the OID for the geometry type. This is PostGIS
82			# specific.
83			cursor = self.connection.cursor()
84			cursor.execute("SELECT OID, typname FROM pg_type WHERE"
85			+" typname = 'geometry'")
86			row = cursor.fetchone()
87			self.connection.commit()
88			if row is not None:
89			self.geometry_type = row[0]
90			else:
91			raise ValueError("Can't determine postgres type of geometries")
92
93	bh	1620	def BriefDescription(self):
94			"""Return a brief, one-line description of the connection
95
96			The return value is suitable for a list box of all database
97			connections.
98			"""
99			return ("postgis://%(user)s@%(host)s:%(port)s/%(dbname)s"
100			% self.__dict__)
101
102	bh	1605	def Close(self):
103			"""Close the database connection"""
104			self.connection.close()
105
106			def GeometryTables(self):
107			"""Return a list with the names of all tables with a geometry column"""
108			cursor = self.connection.cursor()
109			cursor.execute("SELECT f_table_name FROM geometry_columns;")
110			result = [row[0] for row in cursor.fetchall()]
111			self.connection.commit()
112			return result
113
114			def cursor(self):
115			"""Return a DB API 2.0 cursor for the database"""
116			return self.connection.cursor()
117
118
119
120			class PostGISColumn:
121
122			"""Column description for a PostGISTable"""
123
124			def __init__(self, name, type, index):
125			self.name = name
126			self.type = type
127			self.index = index
128
129
130			class PostGISTable:
131
132			"""A Table in a PostGIS database"""
133
134			def __init__(self, db, tablename):
135			"""Initialize the PostGISTable.
136
137			The db parameter should be an instance of PostGISConnection and
138			tablename the name of a table in the database represented by db.
139			"""
140			self.db = db
141			self.tablename = tablename
142			self.column_map = {}
143			self._fetch_table_information()
144
145			def _fetch_table_information(self):
146			"""Internal: Update information about the table"""
147			self.columns = []
148			cursor = self.db.cursor()
149			cursor.execute("SELECT * FROM %s WHERE 0=1" % self.tablename)
150			description = cursor.description
151
152			for i in range(len(description)):
153			for pgtyp, tabletyp in type_map:
154			if pgtyp == description[i][1]:
155			col = PostGISColumn(description[i][0], tabletyp, i)
156			break
157			else:
158			if description[i][1] == self.db.geometry_type:
159			self.geometry_column = description[i][0]
160			# No matching table type. Ignore the column.
161			# FIXME: We should at least print a warning about
162			# ignored columns
163			continue
164			self.columns.append(col)
165
166			for col in self.columns:
167			self.column_map[col.name] = col
168			self.column_map[col.index] = col
169
170			# Build query string for ReadRowAsDict
171			self.query_stmt = ("SELECT %s from %s"
172			% (", ".join([col.name for col in self.columns]),
173			self.tablename))
174
175	bh	1638	def DBConnection(self):
176			"""Return the dbconnection used by the table"""
177			return self.db
178
179			def TableName(self):
180			"""Return the name of the table in the database"""
181			return self.tablename
182
183	bh	1605	def Dependencies(self):
184			"""Return an empty tuple because a PostGISTable depends on nothing else
185			"""
186			return ()
187
188			def NumColumns(self):
189			return len(self.columns)
190
191			def Columns(self):
192			return self.columns
193
194			def Column(self, col):
195			return self.column_map[col]
196
197			def HasColumn(self, col):
198			return self.column_map.has_key(col)
199
200			def NumRows(self):
201			cursor = self.db.cursor()
202			cursor.execute("SELECT count(*) FROM %s" % self.tablename)
203			return cursor.fetchone()[0]
204
205			def ReadRowAsDict(self, row):
206			cursor = self.db.cursor()
207			cursor.execute(self.query_stmt + " LIMIT 1 OFFSET %d" % row)
208			result = {}
209			for col, value in zip(self.columns, cursor.fetchone()):
210			result[col.name] = value
211			return result
212
213			def ReadValue(self, row, col):
214			cursor = self.db.cursor()
215			cursor.execute("SELECT %s FROM %s LIMIT 1 OFFSET %d" %
216			(self.column_map[col].name, self.tablename, row))
217			return cursor.fetchone()[0]
218
219			def ValueRange(self, col):
220			cursor = self.db.cursor()
221			name = self.column_map[col].name
222			cursor.execute("SELECT min(%s), max(%s) FROM %s" %
223			(name, name, self.tablename))
224			return tuple(cursor.fetchone())
225
226			def UniqueValues(self, col):
227			cursor = self.db.cursor()
228			name = self.column_map[col].name
229			cursor.execute("SELECT %s FROM %s GROUP BY %s" %
230			(name, self.tablename, name))
231			return [row[0] for row in cursor.fetchall()]
232
233			def SimpleQuery(self, left, comparison, right):
234			if comparison not in ("==", "!=", "<", "<=", ">=", ">"):
235			raise ValueError("Comparison operator %r not allowed" % comparison)
236
237			if comparison == "==":
238			comparison = "="
239
240			if isinstance(right, PostGISColumn):
241			right_template = right.name
242			params = ()
243			else:
244			right_template = "%s"
245			params = (right,)
246
247			query = "SELECT gid FROM %s WHERE %s %s %s ORDER BY gid;" \
248			% (self.tablename, left.name, comparison, right_template)
249
250			cursor = self.db.cursor()
251			cursor.execute(query, params)
252			result = []
253			while 1:
254			row = cursor.fetchone()
255			if row is None:
256			break
257			result.append(row[0])
258			return result
259
260
261			class PostGISShape:
262
263			def __init__(self, shapeid, data):
264			self.shapeid = shapeid
265			self.data = data
266
267			def compute_bbox(self):
268			"""
269			Return the bounding box of the shape as a tuple (minx,miny,maxx,maxy)
270			"""
271			xs = []
272			ys = []
273			for part in self.Points():
274			for x, y in part:
275			xs.append(x)
276			ys.append(y)
277			return (min(xs), min(ys), max(xs), max(ys))
278
279			def ShapeID(self):
280			return self.shapeid
281
282			def Points(self):
283			return wellknowntext.parse_wkt_thuban(self.data)
284
285			def RawData(self):
286			return self.data
287
288
289			shapetype_map = {"POLYGON": SHAPETYPE_POLYGON,
290			"MULTILINESTRING": SHAPETYPE_ARC,
291			"POINT": SHAPETYPE_POINT}
292
293
294			class PostGISShapeStore(PostGISTable):
295
296			"""Shapestore interface to a table in a PostGIS database"""
297
298			def Table(self):
299			"""Return self since a PostGISShapeStore is its own table."""
300			return self
301
302			def OrigShapeStore(self):
303			"""Return None since the PostGISShapeStore is not derived from another
304			"""
305			return None
306
307			def ShapeType(self):
308			"""Return the type of the shapes in the shapestore."""
309			cursor = self.db.cursor()
310			cursor.execute("SELECT type FROM geometry_columns WHERE"
311			" f_table_name=%s", (self.tablename,))
312			result = cursor.fetchone()[0]
313			cursor.close()
314			return shapetype_map[result]
315
316			def RawShapeFormat(self):
317			"""Return the raw data format of the shape data.
318
319			For the PostGISShapeStore this is RAW_WKT.
320			"""
321			return RAW_WKT
322
323			def NumShapes(self):
324			# The number of shapes is the same as the number of rows,
325			# assuming that the geometry can't be NULL.
326			return self.NumRows()
327
328			def BoundingBox(self):
329			"""Return the bounding box of all shapes in the postgis table"""
330			minx = miny = maxx = maxy = None
331			x=[]
332			y=[]
333			cursor = self.db.cursor()
334			try:
335			stmt = ("SELECT AsText(Envelope(%s)) FROM %s;"
336			% (self.geometry_column, self.tablename))
337			cursor.execute(stmt)
338			result = cursor.fetchone()
339			while result:
340			result = result[0]
341			# Here we must do some parsing through the result string
342			# to get the points out of the polygon which representes
343			# the bounding box The first and the last point of a
344			# polygon are identical
345			result = result.split("(")[2]
346			result = result.split(")")[0]
347			points = result.split(",")
348			del points[4] # Remove the last point
349			for point in points:
350			px, py = point.split()
351			x.append(float(px))
352			y.append(float(py))
353			result = cursor.fetchone()
354			finally:
355			cursor.close()
356			if not x:
357			# Empty table
358			return None
359			return (min(x), min(y), max(x), max(y))
360
361			def Shape(self, shapeid):
362			cursor = self.db.cursor()
363			cursor.execute("SELECT AsText(%s) FROM %s WHERE gid=%d"
364			% (self.geometry_column, self.tablename, shapeid))
365			wkt = cursor.fetchone()[0]
366			cursor.close()
367			return PostGISShape(shapeid, wkt)
368
369			def ShapesInRegion(self, bbox):
370			"""Generate all shapes overlapping the region given by bbox."""
371			# IMPORTANT:This will work for PostGIS < 0.8
372			left, bottom, right, top = bbox
373			geom = (("POLYGON((" + ", ".join(["%f %f"] * 5) + "))")
374			% (left, bottom, left, top, right, top, right, bottom,
375			left, bottom))
376			cursor = self.db.cursor()
377			cursor.execute("SELECT gid, AsText(%s) FROM %s"
378			" WHERE %s && GeometryFromText('%s', -1) ORDER BY gid"
379			% (self.geometry_column, self.tablename,
380			self.geometry_column, geom))
381			while 1:
382			result = cursor.fetchone()
383			if result is None:
384			raise StopIteration
385			yield PostGISShape(result[0], result[1])
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