Code to generate SQL to import building footprints

configuration/generate_footprint_import_sql.py

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+''' Generate an SQL Script to insert Colouring Cities building footprints from GEOJSON Data '''
+
+import json
+
+INPUT_DIRECTORY = "./"
+INPUT_FILENAME = "sg_building_footprint.geojson"
+
+OUTPUT_FILENAME = "generate_footprints.sql"
+
+OUTPUT = []
+
+print(f"Saving to file: '{OUTPUT_FILENAME}' ... ", end='')
+
+OUTPUT.append("DROP TABLE IF EXISTS new_geometries;\n")
+OUTPUT.append("""CREATE TABLE IF NOT EXISTS new_geometries (
+    source_id varchar(30),
+    geometry_geom geometry(GEOMETRY, 3857)
+);\n""")
+
+IDENTIFIER_COUNTER = 1
+
+def file_location():
+    ''' Docstring '''
+    return INPUT_DIRECTORY
+
+def file_location_name():
+    ''' Docstring '''
+    return INPUT_FILENAME
+
+def location_code():
+    ''' Docstring '''
+    # things like "inspire+localmap_intersect5201"
+    # lc - leicester
+    # nc - Newcastle
+    # lbx - area_around_loughborough
+    #return "lbx"
+    return "sgp"
+
+# end of configuration
+
+def fake_toid_prefix():
+    ''' Docstring '''
+    return 'inspire+local_ntrsc_' + location_code()
+
+def files_loaded():
+    ''' Docstring '''
+    return [
+        file_location() + file_location_name()
+    ]
+
+def load_into_table(table, geojson_file):
+    ''' Docstring '''
+    global IDENTIFIER_COUNTER
+
+    with open(geojson_file, 'r', encoding="utf8") as content_file:
+        content = content_file.read()
+        data = json.loads(content)
+        insert_prefix = "INSERT INTO " + table + "(source_id, geometry_geom) VALUES"
+
+        OUTPUT.append(insert_prefix)    #no new line!
+
+        values = []
+
+        for entry in data["features"]:
+            geometry_type = entry["geometry"]["type"]
+
+            if geometry_type == 'MultiPolygon':
+                for ring in entry["geometry"]["coordinates"]:
+                    for coord_list in ring:
+                        for coord in coord_list:
+                            lon = coord[0]
+                            lat = coord[1]
+                            if lon > 180:
+                                raise Exception("out of bounds coordinate")
+                            if lon < -180:
+                                raise Exception("out of bounds coordinate")
+                            if lat > 90:
+                                raise Exception("out of bounds coordinate")
+                            if lat <-90:
+                                raise Exception("out of bounds coordinate")
+            elif geometry_type == 'Polygon':
+                for coord_list in entry["geometry"]["coordinates"]:
+                    for coord in coord_list:
+                        lon = coord[0]
+                        lat = coord[1]
+                        if lon > 180:
+                            raise Exception("out of bounds coordinate")
+                        if lon < -180:
+                            raise Exception("out of bounds coordinate")
+                        if lat > 90:
+                            raise Exception("out of bounds coordinate")
+                        if lat <-90:
+                            raise Exception("out of bounds coordinate")
+            #else:
+                #print(entry["geometry"]["type"])
+                #print(entry["geometry"])
+                #print(entry)
+                #raise Exception("Unexpected type")
+
+            object_id = fake_toid_prefix() + str(IDENTIFIER_COUNTER)
+
+            if len(object_id) > 30:
+                print(object_id)
+                print(len(object_id))
+                raise Exception("Too long")
+
+            values.append("('" + object_id + "', ST_Transform(ST_GeomFromGeoJSON('" + json.dumps(entry["geometry"]) + "'), 3857))")
+
+            IDENTIFIER_COUNTER += 1
+            grouping = 50_000
+
+            if len(values) > grouping:
+                OUTPUT.append(", ".join(values[0:grouping]) + ";\n")
+                values = values[grouping:]
+                OUTPUT.append(insert_prefix)    #no new line
+
+        OUTPUT.append(", ".join(values) + ";\n")
+
+for file in files_loaded():
+    load_into_table("new_geometries", file)
+
+OUTPUT.append("""INSERT INTO geometries ( source_id, geometry_geom )
+         SELECT source_id, geometry_geom
+         FROM new_geometries;\n""")
+OUTPUT.append("""INSERT INTO buildings ( geometry_id, ref_toid )
+         SELECT geometry_id, source_id
+         FROM geometries AS g
+         WHERE EXISTS ( SELECT source_id
+                        FROM new_geometries AS ng
+                        WHERE g.source_id = ng.source_id);\n""")
+OUTPUT.append("DROP TABLE IF EXISTS new_geometries;\n")
+OUTPUT.append("REINDEX TABLE geometries;\n")
+OUTPUT.append("REINDEX TABLE buildings;\n")
+
+with open(OUTPUT_FILENAME, 'w', newline='', encoding="utf8") as f:
+    for row in OUTPUT:
+        f.write(row)
+
+print("Done!")