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	# 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	def has_postgis_support():
24	"""Return whether this Thuban instance supports PostGIS connections
25
26	Having PostGIS support means that the psycopg module can be
27	imported.
28	"""
29	return psycopg is not None
30
31	def psycopg_version():
32	return psycopg.__version__
33
34	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
40	class ConnectionError(Exception):
41
42	"""Class for exceptions occurring when establishing a Databse connection"""
43
44
45	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	self.connect()
68
69	def connect(self):
70	"""Internal: Establish the database connection"""
71	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	try:
77	self.connection = psycopg.connect(" ".join(params))
78	except psycopg.OperationalError, val:
79	raise ConnectionError(str(val))
80
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	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	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	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	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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