Add support for x-plat Sql.Cast()

Author: mythz

src/ServiceStack.OrmLite.MySql/MySqlDialectProviderBase.cs

@@ -216,6 +216,11 @@ public override string SqlConflict(string sql, string conflictResolution)
         public override string SqlCurrency(string fieldOrValue, string currencySymbol) =>
             SqlConcat(new[] { "'" + currencySymbol + "'", "cast(" + fieldOrValue + " as decimal(15,2))" });
 
+        public override string SqlCast(object fieldOrValue, string castAs) => 
+            castAs == Sql.VARCHAR
+                ? $"CAST({fieldOrValue} AS CHAR(1000))"
+                : $"CAST({fieldOrValue} AS {castAs})";
+        
         protected DbConnection Unwrap(IDbConnection db)
         {
             return (DbConnection)db.ToDbConnection();

src/ServiceStack.OrmLite.PostgreSQL/PostgreSQLDialectProvider.cs

@@ -559,6 +559,9 @@ public override string SqlCurrency(string fieldOrValue, string currencySymbol) =
             ? fieldOrValue + "::text::money::text"
             : "replace(" + fieldOrValue + "::text::money::text,'$','" + currencySymbol + "')";
 
+        public override string SqlCast(object fieldOrValue, string castAs) => 
+            $"{fieldOrValue}::{castAs}";
+
         protected NpgsqlConnection Unwrap(IDbConnection db)
         {
             return (NpgsqlConnection)db.ToDbConnection();

src/ServiceStack.OrmLite.SqlServer/SqlServer2016Expression.cs

@@ -28,6 +28,9 @@ protected override object VisitSqlMethodCall(MethodCallExpression m)
                 case nameof(Sql.As):
                     statement = $"{quotedColName} AS {DialectProvider.GetQuotedColumnName(RemoveQuoteFromAlias(args[0].ToString()))}";
                     break;
+                case nameof(Sql.Cast):
+                    statement = DialectProvider.SqlCast(quotedColName, args[0].ToString());
+                    break;
                 case nameof(Sql.Sum):
                 case nameof(Sql.Count):
                 case nameof(Sql.Min):

src/ServiceStack.OrmLite.SqlServer/SqlServerOrmLiteDialectProvider.cs

@@ -556,6 +556,11 @@ public override string SqlLimit(int? offset = null, int? rows = null) => rows ==
                 ? "OFFSET " + offset.GetValueOrDefault() + " ROWS FETCH NEXT " + rows + " ROWS ONLY"
                 : "OFFSET " + offset.GetValueOrDefault(int.MaxValue) + " ROWS";
 
+        public override string SqlCast(object fieldOrValue, string castAs) => 
+            castAs == Sql.VARCHAR
+                ? $"CAST({fieldOrValue} AS VARCHAR(MAX))"
+                : $"CAST({fieldOrValue} AS {castAs})";
+
         protected SqlConnection Unwrap(IDbConnection db) => (SqlConnection)db.ToDbConnection();
 
         protected SqlCommand Unwrap(IDbCommand cmd) => (SqlCommand)cmd.ToDbCommand();

src/ServiceStack.OrmLite/Expressions/Sql.cs

@@ -7,6 +7,8 @@ namespace ServiceStack.OrmLite
 {
     public static partial class Sql
     {
+	    public static string VARCHAR = nameof(VARCHAR); 
+	    
         public static List<object> Flatten(IEnumerable list)
         {
             var ret = new List<object>();
@@ -68,6 +70,8 @@ public static List<object> Flatten(IEnumerable list)
 
         public static T Custom<T>(string customSql) => default(T);
 
+	    public static string Cast(object value, string castAs) => $"CAST({value} AS {castAs})";
+
         public const string EOT= "0 EOT";
     }
 

src/ServiceStack.OrmLite/Expressions/SqlExpression.cs

@@ -2351,6 +2351,9 @@ protected virtual object VisitSqlMethodCall(MethodCallExpression m)
                 case nameof(Sql.As):
                     statement = $"{quotedColName} AS {DialectProvider.GetQuotedColumnName(RemoveQuoteFromAlias(args[0].ToString()))}";
                     break;
+                case nameof(Sql.Cast):
+                    statement = DialectProvider.SqlCast(quotedColName, args[0].ToString());
+                    break;
                 case nameof(Sql.Sum):
                 case nameof(Sql.Count):
                 case nameof(Sql.Min):

src/ServiceStack.OrmLite/IOrmLiteDialectProvider.cs

@@ -220,5 +220,6 @@ string ToCreateIndexStatement<T>(Expression<Func<T, object>> field,
         string SqlCurrency(string fieldOrValue, string currencySymbol);
         string SqlBool(bool value);
         string SqlLimit(int? offset = null, int? rows = null);
+        string SqlCast(object fieldOrValue, string castAs);
     }
 }

src/ServiceStack.OrmLite/OrmLiteDialectProviderBase.cs

@@ -1595,6 +1595,8 @@ public virtual string SqlLimit(int? offset = null, int? rows = null) => rows ==
             : offset == null
                 ? "LIMIT " + rows
                 : "LIMIT " + rows.GetValueOrDefault(int.MaxValue) + " OFFSET " + offset;
+        
+        public virtual string SqlCast(object fieldOrValue, string castAs) => $"CAST({fieldOrValue} AS {castAs})";
 
         //Async API's, should be overrided by Dialect Providers to use .ConfigureAwait(false)
         //Default impl below uses TaskAwaiter shim in async.cs

tests/ServiceStack.OrmLite.Tests/SqlDialectTests.cs

@@ -1,4 +1,5 @@
-using System.Linq;
+using System.Collections.Generic;
+using System.Linq;
 using NUnit.Framework;
 using ServiceStack.DataAnnotations;
 using ServiceStack.Text;
@@ -15,7 +16,7 @@ public class Sqltest
 
     public class SqlDialectTests : OrmLiteTestBase
     {
-        //public SqlDialectTests() : base(Dialect.PostgreSql) {}
+//        public SqlDialectTests() : base(Dialect.SqlServer2008) {}
 
         [Test]
         public void Does_concat_values()
@@ -36,6 +37,26 @@ public void Does_concat_values()
             }
         }
 
+        [Test]
+        public void Does_concat_values_in_SqlExpression()
+        {
+            using (var db = OpenDbConnection())
+            {
+                db.DropAndCreateTable<Sqltest>();
+
+                db.Insert(new Sqltest { Value = 123.456, Bool = true });
+
+                var results = db.Select<Dictionary<string, object>>(db.From<Sqltest>()
+                    .Select(x => new {
+                        x.Id,
+                        text = Sql.As(Sql.Cast(x.Id, Sql.VARCHAR) + " : " + Sql.Cast(x.Value, Sql.VARCHAR) + " : " + Sql.Cast(x.Bool, Sql.VARCHAR) + " string", "text") 
+                    }));
+                
+                Assert.That(results[0]["text"], Is.EqualTo("1 : 123.456 : 1 string")
+                                               .Or.EqualTo("1 : 123.456 : true string"));
+            }
+        }
+
         [Test]
         public void Does_format_currency()
         {