/// <summary>
/// Unify all ordering expressions into a single order expression
/// </summary>
private void FlattenOrderExpressions()
{
List <ServiceQueryPart> newList = new List <ServiceQueryPart>();
ServiceQueryPart orderPart = null;
foreach (ServiceQueryPart part in this._queryParts)
{
if (part.QueryOperator.StartsWith("orderby", StringComparison.Ordinal))
{
orderPart = part;
}
if (part.QueryOperator.StartsWith("thenby", StringComparison.Ordinal))
{
// accumulate secondary ordering expressions
orderPart.Expression += ", " + part.Expression;
}
else
{
newList.Add(part);
}
}
this._queryParts = newList;
}
protected override Expression VisitMethodCall(MethodCallExpression m)
{
ServiceQueryPart holdPart = this._currPart;
StringBuilder holdPartBuilder = this._currPartBuilder;
string methodName = CultureInfo.InvariantCulture.TextInfo.ToLower(m.Method.Name);
if (IsSequenceOperatorCall(m))
{
if (methodName == "where" || methodName == "orderby" || methodName == "orderbydescending" || methodName == "skip" ||
methodName == "take" || methodName == "thenby" || methodName == "thenbydescending")
{
this._currPart = new ServiceQueryPart();
this._currPartBuilder = new StringBuilder();
this._currPart.QueryOperator = methodName;
this._queryParts.Add(this._currPart);
}
else if (methodName == "select")
{
// if the selection specified is anything other than an
// empty selector, throw an exception. I.e. only Select(p => p)
// is supported.
bool isEmptySelection = false;
Expression selector = m.Arguments[1];
if (selector.NodeType == ExpressionType.Quote)
{
LambdaExpression lex = (LambdaExpression)((UnaryExpression)m.Arguments[1]).Operand;
isEmptySelection = (lex.Body.NodeType == ExpressionType.Parameter) &&
(lex.Parameters.Single() == lex.Body);
}
if (!isEmptySelection)
{
throw new NotSupportedException(Resources.QuerySerialization_ProjectionsNotSupported);
}
}
else
{
throw new NotSupportedException(string.Format(CultureInfo.CurrentCulture, Resources.QuerySerialization_UnsupportedQueryOperator, m.Method.Name));
}
Expression obj = this.Visit(m.Object);
IEnumerable <Expression> args = this.Visit(m.Arguments);
if (obj != m.Object || args != m.Arguments)
{
return(Expression.Call(obj, m.Method, args));
}
// post processing
if (methodName == "orderbydescending" || methodName == "thenbydescending")
{
if (methodName == "orderbydescending")
{
this._currPart.QueryOperator = "orderby";
}
else
{
this._currPart.QueryOperator = "thenby";
}
this._currPartBuilder.Append(" desc");
}
}
else if (m.Method.DeclaringType == typeof(Enum) && m.Method.Name == "HasFlag")
{
// Serialize (p => p.enumProp.HasFlag( EnumType.A)) into "(it.enumProp has EnumType.A)"
this._currPartBuilder.Append("(");
this.Visit(m.Object);
// We could convert it to an int here if possible, otherwise we will do it anyway on the server
//this.Visit(Expression.Convert(m.Object, typeof(int)));
this._currPartBuilder.Append(" has ");
// We could convert it to an int here if possible, otherwise we will do it anyway on the server
//this.Visit(Expression.Convert(m.Arguments[0], typeof(int)));
this.Visit(m.Arguments[0]);
this._currPartBuilder.Append(")");
}
else
{
// Ensure that the method is accessible
// Only methods on supported predefined types are allowed
VerifyMethodAccessibility(m);
if (m.Method.IsStatic)
{
this._currPartBuilder.Append(m.Method.DeclaringType.Name);
}
else
{
this.Visit(m.Object);
}
if (m.Object == null || m.Object.NodeType != ExpressionType.Parameter)
{
// for all member accesses other than those directly off of
// our query parameter, we need to append a dot
this._currPartBuilder.Append(".");
}
this._currPartBuilder.AppendFormat(CultureInfo.InvariantCulture, "{0}(", m.Method.Name);
this.VisitMethodParameters(m.Arguments);
this._currPartBuilder.Append(")");
}
if (this._currPart != null)
{
this._currPart.Expression = this._currPartBuilder.ToString();
}
this._currPart = holdPart;
this._currPartBuilder = holdPartBuilder;
return(m);
}
