Refactor SqlServerExpression to use DialectProvider

Author: mythz

src/ServiceStack.OrmLite.SqlServer/SqlServerExpression.cs

@@ -1,57 +1,9 @@
-using System;
 using System.Text;
 
 namespace ServiceStack.OrmLite.SqlServer
 {
 	public class SqlServerExpression<T> : SqlExpression<T>
 	{
-        public override string ToSelectStatement()
-        {
-            if (!Offset.HasValue && !Rows.HasValue)
-                return base.ToSelectStatement();
-
-            AssertValidSkipRowValues();
-
-            var skip = Offset.HasValue ? Offset.Value : 0;
-            var take = Rows.HasValue ? Rows.Value : int.MaxValue;
-
-	        var sql = "";
-
-            //Temporary hack till we come up with a more robust paging sln for SqlServer
-            if (skip == 0)
-            {
-                if (take == int.MaxValue)
-                    return base.ToSelectStatement();
-
-                sql = base.ToSelectStatement();
-                if (sql == null || sql.Length < "SELECT".Length) return sql;
-                var selectType = sql.StartsWithIgnoreCase("SELECT DISTINCT") ? "SELECT DISTINCT" : "SELECT";
-                sql = selectType + " TOP " + take + sql.Substring(selectType.Length, sql.Length - selectType.Length);
-                return sql;
-            }
-	        
-            var orderBy = !String.IsNullOrEmpty(OrderByExpression)
-	                          ? OrderByExpression
-	                          : BuildOrderByIdExpression();
-
-	        OrderByExpression = String.Empty; // Required because ordering is done by Windowing function
-
-            //todo: review needed only check against sql server 2008 R2
-	        var tableName = OrmLiteConfig.DialectProvider.GetQuotedTableName(ModelDef).Trim(); //2
-	        var statement = string.Format("{0} {1} {2}", WhereExpression, GroupByExpression, HavingExpression).Trim(); 
-
-	        var retVal = string.Format(
-	            "{0} FROM (SELECT ROW_NUMBER() OVER ({1}) As RowNum, * FROM {2} {3}) AS RowConstrainedResult WHERE RowNum > {4} AND RowNum <= {5}",
-                SelectExpression,
-	            orderBy,
-	            tableName,
-                statement,
-	            skip,
-	            skip + take);
-
-	        return retVal;
-        }
-
 	    public override SqlExpression<T> Clone()
 	    {
 	        return CopyTo(new SqlServerExpression<T>());
@@ -81,30 +33,5 @@ public override string ToUpdateStatement(T item, bool excludeDefaults = false)
             return string.Format("UPDATE {0} SET {1} {2}",
                 dialectProvider.GetQuotedTableName(ModelDef), setFields, WhereExpression);
         }
-
-        protected virtual void AssertValidSkipRowValues()
-        {
-            if (Offset.HasValue && Offset.Value < 0)
-                throw new ArgumentException(String.Format("Skip value:'{0}' must be>=0", Offset.Value));
-
-            if (Rows.HasValue && Rows.Value <0)
-                throw new ArgumentException(string.Format("Rows value:'{0}' must be>=0", Rows.Value));
-        }
-
-	    protected virtual string BuildOrderByIdExpression()
-	    {
-	        if (ModelDef.PrimaryKey == null)
-                throw new ApplicationException("Malformed model, no PrimaryKey defined");
-
-	        return String.Format("ORDER BY {0}", OrmLiteConfig.DialectProvider.GetQuotedColumnName(ModelDef.PrimaryKey.FieldName));
-	    }
-
-		public override string LimitExpression
-		{
-			get
-			{
-				return "";
-			}
-		}
 	}
 }

src/ServiceStack.OrmLite.SqlServer/SqlServerOrmLiteDialectProvider.cs

@@ -361,5 +361,63 @@ public override string GetColumnDefinition(string fieldName, Type fieldType, boo
 
             return definition;
         }
+
+        public override string ToSelectStatement(ModelDefinition modelDef,
+            string selectExpression,
+            string bodyExpression,
+            string orderByExpression = null,
+            int? offset = null,
+            int? rows = null)
+        {
+            var sb = new StringBuilder(selectExpression);
+            sb.Append(bodyExpression);
+
+            if (!offset.HasValue && !rows.HasValue)
+                return sb + orderByExpression;
+
+            if (offset.HasValue && offset.Value < 0)
+                throw new ArgumentException(string.Format("Skip value:'{0}' must be>=0", offset.Value));
+
+            if (rows.HasValue && rows.Value < 0)
+                throw new ArgumentException(string.Format("Rows value:'{0}' must be>=0", rows.Value));
+
+            var skip = offset.HasValue ? offset.Value : 0;
+            var take = rows.HasValue ? rows.Value : int.MaxValue;
+
+            var selectType = selectExpression.StartsWithIgnoreCase("SELECT DISTINCT") ? "SELECT DISTINCT" : "SELECT";
+
+            //Temporary hack till we come up with a more robust paging sln for SqlServer
+            if (skip == 0)
+            {
+                var sql = sb + orderByExpression;
+
+                if (take == int.MaxValue)
+                    return sql;
+
+                if (sql.Length < "SELECT".Length) return sql;
+                sql = selectType + " TOP " + take + sql.Substring(selectType.Length, sql.Length - selectType.Length);
+                return sql;
+            }
+
+            // Required because ordering is done by Windowing function
+            if (string.IsNullOrEmpty(orderByExpression))
+            {
+                if (modelDef.PrimaryKey == null)
+                    throw new ApplicationException("Malformed model, no PrimaryKey defined");
+
+                orderByExpression = string.Format("ORDER BY {0}",
+                    OrmLiteConfig.DialectProvider.GetQuotedColumnName(modelDef.PrimaryKey.FieldName));
+            }
+
+            var ret = string.Format(
+                "SELECT * FROM (SELECT ROW_NUMBER() OVER ({1}) As RowNum, {0} {2}) AS RowConstrainedResult WHERE RowNum > {3} AND RowNum <= {4}",
+                selectExpression.Substring(selectType.Length),
+                orderByExpression,
+                bodyExpression,
+                skip,
+                take == int.MaxValue ? take : skip + take);
+
+            return ret;
+        }
     }
 }