Add DbDecimal object

Dapper/DbDecimal.cs

@@ -0,0 +1,92 @@
+using System;
+using System.Collections.Generic;
+using System.Data;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Dapper
+{
+    /// <summary>
+    /// This class represents a SQL Decimal (Numeric) type, it can be used if you need 
+    /// to be consistent with query parameter sizes, usually by specifying Precision and Scale
+    /// values that match the type in the database.
+    /// </summary>
+    public sealed class DbDecimal : SqlMapper.ICustomQueryParameter
+    {
+        private const byte _defaultPrecision = 38;
+        private const byte _defaultScale = 8;
+
+        /// <summary>
+        /// The value to be inserted or updated in the database
+        /// </summary>
+        public decimal Value { get; set; } = default;
+
+        /// <summary>
+        /// 
+        /// </summary>
+        public byte Precision { get; set; } = _defaultPrecision;
+
+        /// <summary>
+        /// The number of decimal digits that are stored to the right of the 
+        /// decimal point.
+        /// </summary>
+        public byte Scale { get; set; } = _defaultScale;
+
+        /// <summary>
+        /// The default constructor used when attaching the individual properties 
+        /// of the parameter.
+        /// </summary>
+        public DbDecimal()
+        { }
+
+        /// <summary>
+        /// The primary constructor. This is the constructor that should generally
+        /// be used to create the object because it accepts values for the properties
+        /// used in the 90% use-case.
+        /// </summary>
+        /// <param name="value">The value to be inserted or updated in the database</param>
+        /// <param name="precision">The maximum total number of decimal digits to be stored.</param>
+        /// <param name="scale">The number of decimal digits that are stored to the right of the decimal point.</param>
+        public DbDecimal(decimal value, byte precision, byte scale)
+        {
+            this.Value = value;
+            this.Precision = precision;
+            this.Scale = scale;
+        }
+
+        /// <summary>
+        /// Add the parameter to the command... internal use only
+        /// </summary>
+        /// <param name="command"></param>
+        /// <param name="name"></param>
+        public void AddParameter(IDbCommand command, string name)
+        {
+            bool add = !command.Parameters.Contains(name);
+
+            IDbDataParameter param;
+            if (add)
+            {
+                param = command.CreateParameter();
+                param.ParameterName = name;
+            }
+            else
+            {
+                param = (IDbDataParameter)command.Parameters[name];
+            }
+
+#pragma warning disable 0618
+            param.Value = SqlMapper.SanitizeParameterValue(Value);
+#pragma warning restore 0618
+            param.Precision = this.Precision;
+            param.Scale = this.Scale;
+            param.DbType = DbType.Decimal;
+
+            if (add)
+            {
+                command.Parameters.Add(param);
+            }
+        }
+
+    }
+}

tests/Dapper.Tests/MiscTests.cs

@@ -1270,6 +1270,67 @@ public async void SO35470588_WrongValuePidValue()
             Assert.Equal(568, row.Value);
         }
 
+        [Fact]
+        public void TestDbDecimal()
+        {
+            var obj = connection.Query("select sql_variant_property(@a, 'precision') as a_precision, sql_variant_property(@a, 'scale') as a_scale, " +
+                                              "sql_variant_property(@b, 'precision') as b_precision, sql_variant_property(@b, 'scale') as b_scale, " +
+                                              "sql_variant_property(@c, 'precision') as c_precision, sql_variant_property(@c, 'scale') as c_scale, " +
+                                              "sql_variant_property(@d, 'precision') as d_precision, sql_variant_property(@d, 'scale') as d_scale, " +
+                                              "sql_variant_property(@e, 'precision') as e_precision, sql_variant_property(@e, 'scale') as e_scale",
+                new
+                {
+                    a = new DbDecimal { Value = 123456.78M, Precision = 9, Scale = 3 },
+                    b = new DbDecimal { Value = 123456.78M, Precision = 18, Scale = 3 },
+                    c = new DbDecimal { Value = 123456.78M, Precision = 27, Scale = 3 },
+                    d = new DbDecimal { Value = 123456.78M, Precision = 36, Scale = 3 },
+                    e = new DbDecimal { Value = 123456.78M },
+                }).First();
+
+            Assert.Equal(3, (int)obj.a_scale);
+            Assert.Equal(9, (int)obj.a_precision);
+
+            Assert.Equal(3, (int)obj.b_scale);
+            Assert.Equal(18, (int)obj.b_precision);
+
+            Assert.Equal(3, (int)obj.c_scale);
+            Assert.Equal(27, (int)obj.c_precision);
+
+            Assert.Equal(3, (int)obj.d_scale);
+            Assert.Equal(36, (int)obj.d_precision);
+
+            Assert.Equal(8, (int)obj.e_scale);
+            Assert.Equal(38, (int)obj.e_precision);
+        }
+
+        [Fact]
+        public void TestDbDecimalUsingParameterizedConstructor()
+        {
+            var obj = connection.Query("select sql_variant_property(@a, 'precision') as a_precision, sql_variant_property(@a, 'scale') as a_scale, " +
+                                              "sql_variant_property(@b, 'precision') as b_precision, sql_variant_property(@b, 'scale') as b_scale, " +
+                                              "sql_variant_property(@c, 'precision') as c_precision, sql_variant_property(@c, 'scale') as c_scale, " +
+                                              "sql_variant_property(@d, 'precision') as d_precision, sql_variant_property(@d, 'scale') as d_scale",
+                new
+                {
+                    a = new DbDecimal(123456.78M, 9, 3),
+                    b = new DbDecimal(123456.78M, 18, 3),
+                    c = new DbDecimal(123456.78M, 27, 3),
+                    d = new DbDecimal(123456.78M, 36, 3),
+                }).First();
+
+            Assert.Equal(3, (int)obj.a_scale);
+            Assert.Equal(9, (int)obj.a_precision);
+
+            Assert.Equal(3, (int)obj.b_scale);
+            Assert.Equal(18, (int)obj.b_precision);
+
+            Assert.Equal(3, (int)obj.c_scale);
+            Assert.Equal(27, (int)obj.c_precision);
+
+            Assert.Equal(3, (int)obj.d_scale);
+            Assert.Equal(36, (int)obj.d_precision);
+        }
+
         public class TPTable
         {
             public int Pid { get; set; }