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 Title(self):
        """Return the title of the table.

        The title is currently fixed and equal to the tablename
        """
        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,
                 "MULTIPOLYGON": 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 AllShapes(self):
        cursor = self.db.cursor()
        cursor.execute("SELECT gid, AsText(%s) FROM %s ORDER BY gid"
                       % (self.geometry_column, self.tablename))
        while 1:
            result = cursor.fetchone()
            if result is None:
                return
            yield PostGISShape(result[0], result[1])


    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:
                return
            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	1658	def Title(self):
184			"""Return the title of the table.
185
186			The title is currently fixed and equal to the tablename
187			"""
188			return self.tablename
189
190	bh	1605	def Dependencies(self):
191			"""Return an empty tuple because a PostGISTable depends on nothing else
192			"""
193			return ()
194
195			def NumColumns(self):
196			return len(self.columns)
197
198			def Columns(self):
199			return self.columns
200
201			def Column(self, col):
202			return self.column_map[col]
203
204			def HasColumn(self, col):
205			return self.column_map.has_key(col)
206
207			def NumRows(self):
208			cursor = self.db.cursor()
209			cursor.execute("SELECT count(*) FROM %s" % self.tablename)
210			return cursor.fetchone()[0]
211
212			def ReadRowAsDict(self, row):
213			cursor = self.db.cursor()
214			cursor.execute(self.query_stmt + " LIMIT 1 OFFSET %d" % row)
215			result = {}
216			for col, value in zip(self.columns, cursor.fetchone()):
217			result[col.name] = value
218			return result
219
220			def ReadValue(self, row, col):
221			cursor = self.db.cursor()
222			cursor.execute("SELECT %s FROM %s LIMIT 1 OFFSET %d" %
223			(self.column_map[col].name, self.tablename, row))
224			return cursor.fetchone()[0]
225
226			def ValueRange(self, col):
227			cursor = self.db.cursor()
228			name = self.column_map[col].name
229			cursor.execute("SELECT min(%s), max(%s) FROM %s" %
230			(name, name, self.tablename))
231			return tuple(cursor.fetchone())
232
233			def UniqueValues(self, col):
234			cursor = self.db.cursor()
235			name = self.column_map[col].name
236			cursor.execute("SELECT %s FROM %s GROUP BY %s" %
237			(name, self.tablename, name))
238			return [row[0] for row in cursor.fetchall()]
239
240			def SimpleQuery(self, left, comparison, right):
241			if comparison not in ("==", "!=", "<", "<=", ">=", ">"):
242			raise ValueError("Comparison operator %r not allowed" % comparison)
243
244			if comparison == "==":
245			comparison = "="
246
247			if isinstance(right, PostGISColumn):
248			right_template = right.name
249			params = ()
250			else:
251			right_template = "%s"
252			params = (right,)
253
254			query = "SELECT gid FROM %s WHERE %s %s %s ORDER BY gid;" \
255			% (self.tablename, left.name, comparison, right_template)
256
257			cursor = self.db.cursor()
258			cursor.execute(query, params)
259			result = []
260			while 1:
261			row = cursor.fetchone()
262			if row is None:
263			break
264			result.append(row[0])
265			return result
266
267
268			class PostGISShape:
269
270			def __init__(self, shapeid, data):
271			self.shapeid = shapeid
272			self.data = data
273
274			def compute_bbox(self):
275			"""
276			Return the bounding box of the shape as a tuple (minx,miny,maxx,maxy)
277			"""
278			xs = []
279			ys = []
280			for part in self.Points():
281			for x, y in part:
282			xs.append(x)
283			ys.append(y)
284			return (min(xs), min(ys), max(xs), max(ys))
285
286			def ShapeID(self):
287			return self.shapeid
288
289			def Points(self):
290			return wellknowntext.parse_wkt_thuban(self.data)
291
292			def RawData(self):
293			return self.data
294
295
296			shapetype_map = {"POLYGON": SHAPETYPE_POLYGON,
297	bh	1656	"MULTIPOLYGON": SHAPETYPE_POLYGON,
298	bh	1605	"MULTILINESTRING": SHAPETYPE_ARC,
299			"POINT": SHAPETYPE_POINT}
300
301
302			class PostGISShapeStore(PostGISTable):
303
304			"""Shapestore interface to a table in a PostGIS database"""
305
306			def Table(self):
307			"""Return self since a PostGISShapeStore is its own table."""
308			return self
309
310			def OrigShapeStore(self):
311			"""Return None since the PostGISShapeStore is not derived from another
312			"""
313			return None
314
315			def ShapeType(self):
316			"""Return the type of the shapes in the shapestore."""
317			cursor = self.db.cursor()
318			cursor.execute("SELECT type FROM geometry_columns WHERE"
319			" f_table_name=%s", (self.tablename,))
320			result = cursor.fetchone()[0]
321			cursor.close()
322			return shapetype_map[result]
323
324			def RawShapeFormat(self):
325			"""Return the raw data format of the shape data.
326
327			For the PostGISShapeStore this is RAW_WKT.
328			"""
329			return RAW_WKT
330
331			def NumShapes(self):
332			# The number of shapes is the same as the number of rows,
333			# assuming that the geometry can't be NULL.
334			return self.NumRows()
335
336			def BoundingBox(self):
337			"""Return the bounding box of all shapes in the postgis table"""
338			minx = miny = maxx = maxy = None
339			x=[]
340			y=[]
341			cursor = self.db.cursor()
342			try:
343			stmt = ("SELECT AsText(Envelope(%s)) FROM %s;"
344			% (self.geometry_column, self.tablename))
345			cursor.execute(stmt)
346			result = cursor.fetchone()
347			while result:
348			result = result[0]
349			# Here we must do some parsing through the result string
350			# to get the points out of the polygon which representes
351			# the bounding box The first and the last point of a
352			# polygon are identical
353			result = result.split("(")[2]
354			result = result.split(")")[0]
355			points = result.split(",")
356			del points[4] # Remove the last point
357			for point in points:
358			px, py = point.split()
359			x.append(float(px))
360			y.append(float(py))
361			result = cursor.fetchone()
362			finally:
363			cursor.close()
364			if not x:
365			# Empty table
366			return None
367			return (min(x), min(y), max(x), max(y))
368
369			def Shape(self, shapeid):
370			cursor = self.db.cursor()
371			cursor.execute("SELECT AsText(%s) FROM %s WHERE gid=%d"
372			% (self.geometry_column, self.tablename, shapeid))
373			wkt = cursor.fetchone()[0]
374			cursor.close()
375			return PostGISShape(shapeid, wkt)
376
377	bh	1658	def AllShapes(self):
378			cursor = self.db.cursor()
379			cursor.execute("SELECT gid, AsText(%s) FROM %s ORDER BY gid"
380			% (self.geometry_column, self.tablename))
381			while 1:
382			result = cursor.fetchone()
383			if result is None:
384			return
385			yield PostGISShape(result[0], result[1])
386
387
388	bh	1605	def ShapesInRegion(self, bbox):
389			"""Generate all shapes overlapping the region given by bbox."""
390			# IMPORTANT:This will work for PostGIS < 0.8
391			left, bottom, right, top = bbox
392			geom = (("POLYGON((" + ", ".join(["%f %f"] * 5) + "))")
393			% (left, bottom, left, top, right, top, right, bottom,
394			left, bottom))
395			cursor = self.db.cursor()
396			cursor.execute("SELECT gid, AsText(%s) FROM %s"
397			" WHERE %s && GeometryFromText('%s', -1) ORDER BY gid"
398			% (self.geometry_column, self.tablename,
399			self.geometry_column, geom))
400			while 1:
401			result = cursor.fetchone()
402			if result is None:
403	bh	1658	return
404	bh	1605	yield PostGISShape(result[0], result[1])
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