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 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 Dependencies(self):
176	"""Return an empty tuple because a PostGISTable depends on nothing else
177	"""
178	return ()
179
180	def NumColumns(self):
181	return len(self.columns)
182
183	def Columns(self):
184	return self.columns
185
186	def Column(self, col):
187	return self.column_map[col]
188
189	def HasColumn(self, col):
190	return self.column_map.has_key(col)
191
192	def NumRows(self):
193	cursor = self.db.cursor()
194	cursor.execute("SELECT count(*) FROM %s" % self.tablename)
195	return cursor.fetchone()[0]
196
197	def ReadRowAsDict(self, row):
198	cursor = self.db.cursor()
199	cursor.execute(self.query_stmt + " LIMIT 1 OFFSET %d" % row)
200	result = {}
201	for col, value in zip(self.columns, cursor.fetchone()):
202	result[col.name] = value
203	return result
204
205	def ReadValue(self, row, col):
206	cursor = self.db.cursor()
207	cursor.execute("SELECT %s FROM %s LIMIT 1 OFFSET %d" %
208	(self.column_map[col].name, self.tablename, row))
209	return cursor.fetchone()[0]
210
211	def ValueRange(self, col):
212	cursor = self.db.cursor()
213	name = self.column_map[col].name
214	cursor.execute("SELECT min(%s), max(%s) FROM %s" %
215	(name, name, self.tablename))
216	return tuple(cursor.fetchone())
217
218	def UniqueValues(self, col):
219	cursor = self.db.cursor()
220	name = self.column_map[col].name
221	cursor.execute("SELECT %s FROM %s GROUP BY %s" %
222	(name, self.tablename, name))
223	return [row[0] for row in cursor.fetchall()]
224
225	def SimpleQuery(self, left, comparison, right):
226	if comparison not in ("==", "!=", "<", "<=", ">=", ">"):
227	raise ValueError("Comparison operator %r not allowed" % comparison)
228
229	if comparison == "==":
230	comparison = "="
231
232	if isinstance(right, PostGISColumn):
233	right_template = right.name
234	params = ()
235	else:
236	right_template = "%s"
237	params = (right,)
238
239	query = "SELECT gid FROM %s WHERE %s %s %s ORDER BY gid;" \
240	% (self.tablename, left.name, comparison, right_template)
241
242	cursor = self.db.cursor()
243	cursor.execute(query, params)
244	result = []
245	while 1:
246	row = cursor.fetchone()
247	if row is None:
248	break
249	result.append(row[0])
250	return result
251
252
253	class PostGISShape:
254
255	def __init__(self, shapeid, data):
256	self.shapeid = shapeid
257	self.data = data
258
259	def compute_bbox(self):
260	"""
261	Return the bounding box of the shape as a tuple (minx,miny,maxx,maxy)
262	"""
263	xs = []
264	ys = []
265	for part in self.Points():
266	for x, y in part:
267	xs.append(x)
268	ys.append(y)
269	return (min(xs), min(ys), max(xs), max(ys))
270
271	def ShapeID(self):
272	return self.shapeid
273
274	def Points(self):
275	return wellknowntext.parse_wkt_thuban(self.data)
276
277	def RawData(self):
278	return self.data
279
280
281	shapetype_map = {"POLYGON": SHAPETYPE_POLYGON,
282	"MULTILINESTRING": SHAPETYPE_ARC,
283	"POINT": SHAPETYPE_POINT}
284
285
286	class PostGISShapeStore(PostGISTable):
287
288	"""Shapestore interface to a table in a PostGIS database"""
289
290	def Table(self):
291	"""Return self since a PostGISShapeStore is its own table."""
292	return self
293
294	def OrigShapeStore(self):
295	"""Return None since the PostGISShapeStore is not derived from another
296	"""
297	return None
298
299	def ShapeType(self):
300	"""Return the type of the shapes in the shapestore."""
301	cursor = self.db.cursor()
302	cursor.execute("SELECT type FROM geometry_columns WHERE"
303	" f_table_name=%s", (self.tablename,))
304	result = cursor.fetchone()[0]
305	cursor.close()
306	return shapetype_map[result]
307
308	def RawShapeFormat(self):
309	"""Return the raw data format of the shape data.
310
311	For the PostGISShapeStore this is RAW_WKT.
312	"""
313	return RAW_WKT
314
315	def NumShapes(self):
316	# The number of shapes is the same as the number of rows,
317	# assuming that the geometry can't be NULL.
318	return self.NumRows()
319
320	def BoundingBox(self):
321	"""Return the bounding box of all shapes in the postgis table"""
322	minx = miny = maxx = maxy = None
323	x=[]
324	y=[]
325	cursor = self.db.cursor()
326	try:
327	stmt = ("SELECT AsText(Envelope(%s)) FROM %s;"
328	% (self.geometry_column, self.tablename))
329	cursor.execute(stmt)
330	result = cursor.fetchone()
331	while result:
332	result = result[0]
333	# Here we must do some parsing through the result string
334	# to get the points out of the polygon which representes
335	# the bounding box The first and the last point of a
336	# polygon are identical
337	result = result.split("(")[2]
338	result = result.split(")")[0]
339	points = result.split(",")
340	del points[4] # Remove the last point
341	for point in points:
342	px, py = point.split()
343	x.append(float(px))
344	y.append(float(py))
345	result = cursor.fetchone()
346	finally:
347	cursor.close()
348	if not x:
349	# Empty table
350	return None
351	return (min(x), min(y), max(x), max(y))
352
353	def Shape(self, shapeid):
354	cursor = self.db.cursor()
355	cursor.execute("SELECT AsText(%s) FROM %s WHERE gid=%d"
356	% (self.geometry_column, self.tablename, shapeid))
357	wkt = cursor.fetchone()[0]
358	cursor.close()
359	return PostGISShape(shapeid, wkt)
360
361	def ShapesInRegion(self, bbox):
362	"""Generate all shapes overlapping the region given by bbox."""
363	# IMPORTANT:This will work for PostGIS < 0.8
364	left, bottom, right, top = bbox
365	geom = (("POLYGON((" + ", ".join(["%f %f"] * 5) + "))")
366	% (left, bottom, left, top, right, top, right, bottom,
367	left, bottom))
368	cursor = self.db.cursor()
369	cursor.execute("SELECT gid, AsText(%s) FROM %s"
370	" WHERE %s && GeometryFromText('%s', -1) ORDER BY gid"
371	% (self.geometry_column, self.tablename,
372	self.geometry_column, geom))
373	while 1:
374	result = cursor.fetchone()
375	if result is None:
376	raise StopIteration
377	yield PostGISShape(result[0], result[1])
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