private IFieldFilter AddFieldFilter(string name, object value, ComparisonConstants comparsion)
{
//handle enums
if (value != null)
{
if (value.GetType().BaseType.FullName == "System.Enum")
{
value = Convert.ToInt32(value);
}
}
var filter = (IFieldFilter) new FieldFilter();
filter.Comparer = comparsion;
filter.Name = name;
filter.Value = value;
if (FieldFilters == null)
{
FieldFilters = new List <IFieldFilter>();
}
//if (this.FieldFilters.FindIndex(x => x.Name == filter.Name) >= 0)
// throw new InvalidOperationException($"Duplicate filter field \"{filter.Name}\" was encountered.");
FieldFilters.Add(filter);
return(filter);
}
private bool ParseExpression(MemberExpression memberExpr, Expression valueExpr, ComparisonConstants comparison)
{
try
{
if (memberExpr == null)
{
return(false);
}
var constantExpr = valueExpr as ConstantExpression;
if (constantExpr != null)
{
AddFieldFilter(memberExpr.Member.Name, constantExpr.Value, comparison);
return(true);
}
// This is kinda of weird the compiler creates an object for the variables in a where conditions
// For example, Where(x => x.Category != f)
var memberAccessValueExpr = valueExpr as MemberExpression;
if (memberAccessValueExpr != null)
{
var theValue = ExpressionHelper.GetMemberExpressionValue(memberAccessValueExpr);
AddFieldFilter(memberExpr.Member.Name, theValue, comparison);
return(true);
}
var unaryExpressionExpr = valueExpr as UnaryExpression;
if (unaryExpressionExpr != null)
{
var theValue = ExpressionHelper.GetMemberExpressionValue(unaryExpressionExpr);
AddFieldFilter(memberExpr.Member.Name, theValue, comparison);
return(true);
}
var methodExpressionExpr = valueExpr as MethodCallExpression;
if (methodExpressionExpr != null)
{
//Parse DateTime functions like AddDays, etc.
//if (methodExpressionExpr.Method.DeclaringType.FullName == "System.DateTime")
{
var objectMember = Expression.Convert(methodExpressionExpr, typeof(object));
var getterLambda = Expression.Lambda <Func <object> >(objectMember);
var getter = getterLambda.Compile();
var theValue = getter();
AddFieldFilter(memberExpr.Member.Name, theValue, comparison);
return(true);
}
}
return(false);
}
catch (Exception ex)
{
LoggerCQ.LogError(ex);
return(false);
}
}
private void ParseExpression(BinaryExpression expression, ComparisonConstants comparison)
{
// Handles Where(x => X.Field == 5); Or
// Handles Where(x => 5 == X.Field); Or
// Handles Where(x => X.Field == variable); Or
// Handles Where(x => variable == X.Field);
var leftExpr = expression.Left;
var rightExpr = expression.Right;
#region Setup Left/Right
//If a value and property are different nullable/not nullable there is a convert done so get the real memeber expression
var convertPropertyExpr = leftExpr as UnaryExpression;
if (convertPropertyExpr != null && convertPropertyExpr.NodeType == ExpressionType.Convert)
{
var memExp = convertPropertyExpr.Operand as MemberExpression;
if (memExp != null)
{
leftExpr = memExp;
}
}
convertPropertyExpr = rightExpr as UnaryExpression;
if (convertPropertyExpr != null && convertPropertyExpr.NodeType == ExpressionType.Convert)
{
var memExp = convertPropertyExpr.Operand as MemberExpression;
if (memExp != null)
{
rightExpr = memExp;
}
}
#endregion
if (!ParseExpression(leftExpr as MemberExpression, rightExpr, comparison))
{
//we are flipping this equaltion so flip the comparer
//i.e. 1<X => X>1
var newComp = comparison;
switch (comparison)
{
case ComparisonConstants.GreaterThan:
newComp = ComparisonConstants.LessThan;
break;
case ComparisonConstants.GreaterThanOrEq:
newComp = ComparisonConstants.LessThanOrEq;
break;
case ComparisonConstants.LessThan:
newComp = ComparisonConstants.GreaterThan;
break;
case ComparisonConstants.LessThanOrEq:
newComp = ComparisonConstants.GreaterThanOrEq;
break;
}
if (!ParseExpression(rightExpr as MemberExpression, leftExpr, newComp))
{
throw new InvalidOperationException("Invalid where condition expression.");
}
}
}