Merge pull request #18 from mattmakesmaps/development

Release 0.2.2

Author: mattmakesmaps

CHANGES.txt

@@ -2,6 +2,13 @@
 CHANGES
 =======
 
+Release 0.2.2
+-------------
+
+* Refactor geojson.py --> constructors.py
+* Documented duck type interface for constructor classes.
+* Updated README.txt to reflect new entry point.
+
 Release 0.2.1
 -------------
 

README.txt

@@ -20,7 +20,7 @@ Listed below is the --help usage information.::
 
     POST GeoJSON or TopoJSON features from PostGIS to a Github Gist.
 
-    Example usage: python pgsql2gist.py --host localhost --user matt tilestache \
+    Example usage: pgsql2gist --host localhost --user matt tilestache \
                    "SELECT name, ST_AsGeoJSON(geom) AS geometry FROM neighborhoods LIMIT 5;"
 
     Current SELECT Statement Requirements:

pgsql2gist/__init__.py

@@ -5,4 +5,4 @@
 from .gisthandler import GistAPIHandler
 from .pgconn import PostGISConnection
 from .cli import CLIInterface
-from .geojson import GeoJSONConstructor, OutOfBoundsError
+from .constructors import GeoJSONConstructor, TopoJSONConstructor, OutOfBoundsError

pgsql2gist/cli.py

@@ -15,6 +15,8 @@ def __init__(self):
         """
         self.parser = argparse.ArgumentParser(add_help=False,
                                               formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+        # Internal Attribute will be used to populate dictionary in get_args_dict() method.
+        self._format = None
         # Build Parser
         self.setup()
 
@@ -40,12 +42,14 @@ def setup(self):
 
     def get_args_dict(self):
         """
-        Given an argparse parser object, wrap in a call to vars(), returning dictionary.
+        Given an argparse parser object, wrap in a call to vars(), returning a dictionary of attributes.
         This method also calls the input validation method.
         """
         args = self.parser.parse_args()
         args_dict = vars(args)
         if self._validate_args_dict(args_dict):
+            # Expose internal _format attribute along with dictionary of arg parse attributes.
+            args_dict["format"] = self._format
             return args_dict
 
     def _validate_args_dict(self, args_dict):
@@ -67,16 +71,19 @@ def _validate_file_ext(self, args_dict):
         """
         Validate that file extensions are either geojson or topojson.
         Required for data to render in mapping interface.
+
+        Set the class' _format attribute.
         """
-        valid_extensions = ['.geojson', 'topojson']
+        valid_extensions = ['geojson', 'topojson']
         ext_is_valid = False
         for ext in valid_extensions:
             if args_dict['file'].endswith(ext):
+                self._format = ext
                 ext_is_valid = True
         if ext_is_valid:
             return True
         else:
-            raise ValueError('File extension does not end in .geojson or .topojson')
+            raise ValueError("File does not end in '.geojson' or '.topojson'. NOTE: Gist API is case-sensitive.")
 
     def _validate_topojson_geojson_call(self, args_dict):
         """

pgsql2gist/command_line.py

@@ -4,7 +4,7 @@
 """
 POST GeoJSON or TopoJSON features from PostGIS to a Github Gist.
 
-Example usage: python pgsql2gist.py --host localhost --user matt tilestache \
+Example usage: pgsql2gist --host localhost --user matt tilestache \
                "SELECT name, ST_AsGeoJSON(geom) AS geometry FROM neighborhoods LIMIT 5;"
 
 Current SELECT Statement Requirements:
@@ -39,7 +39,7 @@
 # Import relevant modules from the pgsql2gist package.
 import time
 from psycopg2 import Error
-from pgsql2gist import GistAPIHandler, PostGISConnection, CLIInterface, GeoJSONConstructor
+from pgsql2gist import GistAPIHandler, PostGISConnection, CLIInterface, GeoJSONConstructor, TopoJSONConstructor
 
 
 def main():
@@ -58,8 +58,14 @@ def main():
                 # Get results
             query_results = db.fetchall()
 
-        # Create GeoJSON Feature Collection
-        features = GeoJSONConstructor(query_results, args["geom_col"]).encode()
+        # Mapping of file extensions to constructor classes
+        constructor_lookup = {'geojson': GeoJSONConstructor,
+                              'topojson': TopoJSONConstructor}
+
+        # Create Constructor and Execute Encode Method
+        constructor = constructor_lookup[args["format"]]
+        features = constructor(query_results, args["geom_col"]).encode()
+
         # Setup and create request to Gist API
         gist_handler = GistAPIHandler(args["file"], args["description"], features)
         gist_handler.create()

pgsql2gist/geojson.py renamed to pgsql2gist/constructors.py

@@ -1,5 +1,30 @@
 __author__ = 'matt'
 __date__ = '11/24/13'
+"""
+Constructors are classes that are designed to accept geometry/attribute data as input,
+and convert to a serialized string, for POST'ing to Github using the Gist API.
+
+Constructor classes rely on a duck typed interface. A stub class looks like the following:
+
+class TopoJSONConstructor(object):
+    def __init__(self, records, geom_col='geometry'):
+        self.records = records
+        self.geom_col = geom_col
+
+    def encode(self):
+        raise NotImplementedError("TopoJSON Support Not Implemented In This Version.")
+
+As seen above the required attributes for a constructor class are:
+records - A list of dictionaries. Each dictionary represents a record to be serialized.
+          Dictionary key/values represent properties (tabular+geometry) for the record.
+          This attribute can be populated from any data source, but within the context
+          of this application, is the result of a call to psycopg2's fetchall() method.
+geom_col - A string representing the key for the a record dictionary (contained in the
+           records list) that holds geometry information. Defaults to 'geometry'
+
+An 'encode()' method is also required. This method should return a string representing the
+serialized geometry with attributes.
+"""
 
 import collections
 import json
@@ -17,8 +42,6 @@ class GeoJSONConstructor(object):
     records (LIST) - Each element is a dictionary representing
     columns and values for a single geojson feature.
     geom_col (STRING) - Indicates which dict key represents the geometry column.
-
-    TODO: Include validation checks. Add Exception Handling.
     """
     def __init__(self, records, geom_col='geometry'):
         self.records = records
@@ -90,3 +113,21 @@ def encode(self):
         features = [self.make_feature(row, self.geom_col) for row in self.records]
         feature_collection = self.make_feature_collection(features)
         return feature_collection
+
+
+class TopoJSONConstructor(object):
+    """
+    Given the following inputs, generate a TopoJSON feature collection.
+
+    Required Parameters:
+    records (LIST) - Each element is a dictionary representing
+    columns and values for a single geojson feature.
+    geom_col (STRING) - Indicates which dict key represents the geometry column.
+    """
+
+    def __init__(self, records, geom_col='geometry'):
+        self.records = records
+        self.geom_col = geom_col
+
+    def encode(self):
+        raise NotImplementedError("TopoJSON Support Not Implemented In This Version.")

setup.py

@@ -2,7 +2,7 @@
 
 setup(
     name='pgsql2gist',
-    version='0.2.1',
+    version='0.2.2',
     author='Matthew Kenny',
     author_email='matthewkenny AT gmail DOT com',
     classifiers=[