Fix mapping of PG money

Fixes #1467

(cherry picked from commit a213f868)

src/EFCore.PG/Storage/Internal/Mapping/NpgsqlMoneyTypeMapping.cs

+using System;
+using System.Data.Common;
+using Microsoft.EntityFrameworkCore.Storage;
+using NpgsqlTypes;
+
+namespace Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.Mapping
+{
+    public class NpgsqlMoneyTypeMapping : DecimalTypeMapping
+    {
+        public NpgsqlMoneyTypeMapping() : base("money", System.Data.DbType.Currency) {}
+
+        protected NpgsqlMoneyTypeMapping(RelationalTypeMappingParameters parameters)
+            : base(parameters)
+        {
+        }
+
+        protected override RelationalTypeMapping Clone(RelationalTypeMappingParameters parameters)
+            => new NpgsqlMoneyTypeMapping();
+
+        protected override string GenerateNonNullSqlLiteral(object value)
+            => base.GenerateNonNullSqlLiteral(value) + "::money";
+    }
+}

src/EFCore.PG/Storage/Internal/NpgsqlTypeMappingSource.cs

@@ -34,7 +34,7 @@ public class NpgsqlTypeMappingSource : RelationalTypeMappingSource
         readonly FloatTypeMapping              _float4             = new FloatTypeMapping("real", DbType.Single);
         readonly DoubleTypeMapping             _float8             = new DoubleTypeMapping("double precision", DbType.Double);
         readonly DecimalTypeMapping            _numeric            = new DecimalTypeMapping("numeric", DbType.Decimal);
-        readonly DecimalTypeMapping            _money              = new DecimalTypeMapping("money");
+        readonly NpgsqlMoneyTypeMapping        _money              = new NpgsqlMoneyTypeMapping();
         readonly GuidTypeMapping               _uuid               = new GuidTypeMapping("uuid", DbType.Guid);
         readonly ShortTypeMapping              _int2               = new ShortTypeMapping("smallint", DbType.Int16);
         readonly ByteTypeMapping               _int2Byte           = new ByteTypeMapping("smallint", DbType.Byte);

test/EFCore.PG.FunctionalTests/BuiltInDataTypesNpgsqlTest.cs

@@ -459,7 +459,7 @@ public virtual void Can_insert_and_read_back_all_mapped_data_types()
 @p8='2016-01-02T11:11:12' (DbType = DateTimeOffset)
 @p9='0001-01-01T12:00:00.0000000+02:00' (DbType = Object)
 @p10='101.7'
-@p11='81.1'
+@p11='81.1' (DbType = Currency)
 @p12='103.9'
 @p13='System.Collections.Generic.Dictionary`2[System.String,System.String]' (Nullable = false) (DbType = Object)
 @p14='85.5'
@@ -869,7 +869,7 @@ public void Sum_Conversions()
         {
             using var context = CreateContext();
 
-            // PostgreSQL SUM() returns numeric for bigint input, bigint for int/smallint inuts.
+            // PostgreSQL SUM() returns numeric for bigint input, bigint for int/smallint ints.
             // Make sure the proper conversion is done
             var sum1 = context.Set<MappedDataTypes>().Sum(m => m.LongAsBigint);
             var sum2 = context.Set<MappedDataTypes>().Sum(m => m.Int);
@@ -886,6 +886,23 @@ public void Sum_Conversions()
 FROM ""MappedDataTypes"" AS m");
         }
 
+        [ConditionalFact]
+        public void Money_compare_constant()
+        {
+            using var context = CreateContext();
+
+            _ = context.Set<MappedDataTypes>().Where(m => m.DecimalAsMoney > 3).ToList();
+        }
+
+        [ConditionalFact]
+        public void Money_compare_parameter()
+        {
+            using var context = CreateContext();
+
+            var money = 3m;
+            _ = context.Set<MappedDataTypes>().Where(m => m.DecimalAsMoney > money).ToList();
+        }
+
         void AssertSql(params string[] expected)
             => Fixture.TestSqlLoggerFactory.AssertBaseline(expected);
 

test/EFCore.PG.FunctionalTests/TestModels/Northwind/NorthwindNpgsqlContext.cs

@@ -27,20 +27,8 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
             modelBuilder.Entity<Order>()
                 .Property(o => o.EmployeeID)
                 .HasColumnType("int4");
-            modelBuilder.Entity<OrderDetail>()
-                .Property(od => od.UnitPrice)
-                .HasColumnType("money");
 
-            modelBuilder.Entity<Product>(
-                b =>
-                {
-                    b.Property(p => p.UnitPrice).HasColumnType("money");
-                    b.Property(p => p.UnitsInStock).HasColumnType("int2");
-                });
-
-            modelBuilder.Entity<MostExpensiveProduct>()
-                .Property(p => p.UnitPrice)
-                .HasColumnType("money");
+            modelBuilder.Entity<Product>(b => b.Property(p => p.UnitsInStock).HasColumnType("int2"));
 
 #pragma warning disable CS0618 // Type or member is obsolete
             modelBuilder.Query<CustomerView>().HasNoKey().ToQuery(