/// <summary>
/// Creates a filter expression from a filter group
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="filterGroup"></param>
/// <param name="parameterName"></param>
/// <returns></returns>
public static Expression <Func <T, bool> > GetFilterExpression <T>(this FilterGroup filterGroup, string parameterName = "f") where T : class
{
if (filterGroup == null ||
((filterGroup.FilterGroups == null || filterGroup.FilterGroups.Count() == 0) && (filterGroup.Filters == null || filterGroup.Filters.Count() == 0)))
{
return(null);
}
List <Filter> filters = filterGroup.GetAll();
List <object> values = filters.Select(f =>
{
MemberInfo pInfo = typeof(T).GetMemberInfoFromFullName(f.Field);
if (f.Value != null && pInfo.GetMemberType() != f.Value.GetType()) //convert values if necessary
{
f.Value = Convert.ChangeType(f.Value, pInfo.GetMemberType()); //NewtonSoft Json defaults to long for whole numbers and double for fractions
}
return(f.Value);
}).ToList();
return(System.Linq.Dynamic.Core.DynamicExpressionParser.ParseLambda
(
false,
new ParameterExpression[] { Expression.Parameter(typeof(T), parameterName) },
typeof(bool),
filterGroup.ToExpression <T>(filters, parameterName, values, false),
values.ToArray()
) as Expression <Func <T, bool> >);
}
