[Enhancement] Add support for additonal types which are created via extensions e.g Geospatial objects.

lib/src/binary_codec.dart

@@ -290,20 +290,20 @@ class PostgresBinaryDecoder extends Converter<Uint8List, dynamic> {
     }
   }
 
-  static final Map<int, PostgreSQLDataType> typeMap = {
-    16: PostgreSQLDataType.boolean,
-    17: PostgreSQLDataType.byteArray,
-    19: PostgreSQLDataType.name,
-    20: PostgreSQLDataType.bigInteger,
-    21: PostgreSQLDataType.smallInteger,
-    23: PostgreSQLDataType.integer,
-    25: PostgreSQLDataType.text,
-    700: PostgreSQLDataType.real,
-    701: PostgreSQLDataType.double,
-    1082: PostgreSQLDataType.date,
-    1114: PostgreSQLDataType.timestampWithoutTimezone,
-    1184: PostgreSQLDataType.timestampWithTimezone,
-    2950: PostgreSQLDataType.uuid,
-    3802: PostgreSQLDataType.json,
-  };
+  // static final Map<int, PostgreSQLDataType> typeMap = {
+  //   16: PostgreSQLDataType.boolean,
+  //   17: PostgreSQLDataType.byteArray,
+  //   19: PostgreSQLDataType.name,
+  //   20: PostgreSQLDataType.bigInteger,
+  //   21: PostgreSQLDataType.smallInteger,
+  //   23: PostgreSQLDataType.integer,
+  //   25: PostgreSQLDataType.text,
+  //   700: PostgreSQLDataType.real,
+  //   701: PostgreSQLDataType.double,
+  //   1082: PostgreSQLDataType.date,
+  //   1114: PostgreSQLDataType.timestampWithoutTimezone,
+  //   1184: PostgreSQLDataType.timestampWithTimezone,
+  //   2950: PostgreSQLDataType.uuid,
+  //   3802: PostgreSQLDataType.json,
+  // };
 }

lib/src/connection.dart

@@ -6,6 +6,7 @@ import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:buffer/buffer.dart';
+import 'package:postgres/postgres.dart';
 
 import 'client_messages.dart';
 import 'execution_context.dart';
@@ -167,6 +168,8 @@ class PostgreSQLConnection extends Object
 
       await connectionComplete.future
           .timeout(Duration(seconds: timeoutInSeconds));
+
+      await _scanPostgresTypes();
     } on TimeoutException catch (e, st) {
       final err = PostgreSQLException(
           'Failed to connect to database $host:$port/$databaseName failed to connect.');
@@ -179,6 +182,52 @@ class PostgreSQLConnection extends Object
     }
   }
 
+  Future createExtension(String extensionName) async {
+    try {
+      await _query('CREATE EXTENSION IF NOT EXISTS @name',
+          substitutionValues: {'name': extensionName});
+      // After creating an extension e.g CREATE EXTENSION postgis or create extension hstore -> the data type is added to pg_types which contains oid and typename from postgres.
+      // i.e values stored in the PostgresBinaryDecoder.typeMap. To have this driver able to understand any postgres type, scanPostgresTypes should scan database on connecting/after creating and extension.
+      //
+      await scanPostgresTypes();
+    } catch (e, st) {
+      await _close(e, st);
+
+      rethrow;
+    }
+  }
+
+  Future scanPostgresTypes() => _scanPostgresTypes();
+
+  Future _scanPostgresTypes() async {
+    // fetch oids from database (dynamic values)
+    final dataTypes = await _connection.query(
+      '''
+        select oid::int,typname from pg_type where typname in ('text','int2','int4','int8','float4','float8','bool','date','bytea', 'timestamp','timestamptz','jsonb','name','uuid');
+        ''',
+      allowReuse: false,
+    );
+
+    final mapped = dataTypes.map((row) {
+      final oid = row[0] as int;
+      final typname = row[1] as String;
+      return MapEntry<String, int>(typname, oid);
+    });
+    final _extraDataTypes = <String, int>{};
+
+    _extraDataTypes.addEntries(mapped);
+
+    typeMap = _extraDataTypes.map((key, value) {
+      // add boolean since it's not called bool on pg_types
+      if (key == 'bool') {
+        return MapEntry<int, PostgreSQLDataType>(
+            value, PostgreSQLFormatIdentifier.typeStringToCodeMap['boolean']);
+      }
+      return MapEntry<int, PostgreSQLDataType>(
+          value, PostgreSQLFormatIdentifier.typeStringToCodeMap[key]);
+    });
+  }
+
   /// Closes a connection.
   ///
   /// After the returned [Future] completes, this connection can no longer be used to execute queries. Any queries in progress or queued are cancelled.

lib/src/query.dart

@@ -121,8 +121,7 @@ class Query<T> {
         return true;
       }
 
-      final actualType = PostgresBinaryDecoder
-          .typeMap[actualParameterTypeCodeIterator.current];
+      final actualType = typeMap[actualParameterTypeCodeIterator.current];
       return actualType == specifiedType;
     }).any((v) => v == false);
 

lib/src/types.dart

@@ -66,3 +66,20 @@ enum PostgreSQLDataType {
   /// When returned from database, format will be xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
   uuid
 }
+
+Map<int, PostgreSQLDataType> typeMap = {
+  16: PostgreSQLDataType.boolean,
+  17: PostgreSQLDataType.byteArray,
+  19: PostgreSQLDataType.name,
+  20: PostgreSQLDataType.bigInteger,
+  21: PostgreSQLDataType.smallInteger,
+  23: PostgreSQLDataType.integer,
+  25: PostgreSQLDataType.text,
+  700: PostgreSQLDataType.real,
+  701: PostgreSQLDataType.double,
+  1082: PostgreSQLDataType.date,
+  1114: PostgreSQLDataType.timestampWithoutTimezone,
+  1184: PostgreSQLDataType.timestampWithTimezone,
+  2950: PostgreSQLDataType.uuid,
+  3802: PostgreSQLDataType.json,
+};

test/encoding_test.dart

@@ -405,7 +405,7 @@ Future expectInverse(dynamic value, PostgreSQLDataType dataType) async {
     dataType = PostgreSQLDataType.bigInteger;
   }
   int code;
-  PostgresBinaryDecoder.typeMap.forEach((key, type) {
+  typeMap.forEach((key, type) {
     if (type == dataType) {
       code = key;
     }