[.net] LINQ to Entities does not recognize the method

I'm getting the following error when trying to do a linq query:

LINQ to Entities does not recognize the method 'Boolean IsCharityMatching(System.String, System.String)' method, and this method cannot be translated into a store expression.

I've read lots of previous questions where people get the same error, and if I understand this correctly it's because LINQ to Entities requires the whole linq query expression to be translated to a server query, and therefore you can't call an outside method in it. I haven't been able to convert my scenario into something that works yet, and my brain is starting to melt down, so I was hoping someone could point me in the right direction. We're using Entity Framework and the specification pattern (and I'm new to both).

Here's the code that uses the specification:

ISpecification<Charity> specification = new CharitySearchSpecification(charityTitle, charityReference);

charities = charitiesRepository.Find(specification).OrderBy(p => p.RegisteredName).ToList();

Here's the linq expression:

public System.Linq.Expressions.Expression<Func<Charity, bool>> IsSatisfied()
{
    return p => p.IsCharityMatching(this.charityName, this.charityReference);
}

Here's the IsCharityMatching method:

public bool IsCharityMatching(string name, string referenceNumber)
{
    bool exists = true;

    if (!String.IsNullOrEmpty(name))
    {
        if (!this.registeredName.ToLower().Contains(name.ToLower()) &&
            !this.alias.ToLower().Contains(name.ToLower()) &&
           !this.charityId.ToLower().Contains(name.ToLower()))
        {
            exists = false;
        }
    }

    if (!String.IsNullOrEmpty(referenceNumber))
    {
        if (!this.charityReference.ToLower().Contains(referenceNumber.ToLower()))
        {
            exists = false;
        }
    }

    return exists;
}

Let me know if you need any more information.

Many thanks,

Annelie

If anyone is looking for a VB.Net answer (as I was initially), here it is:

Public Function IsSatisfied() As Expression(Of Func(Of Charity, String, String, Boolean))

Return Function(charity, name, referenceNumber) (String.IsNullOrWhiteSpace(name) Or
                                                         charity.registeredName.ToLower().Contains(name.ToLower()) Or
                                                         charity.alias.ToLower().Contains(name.ToLower()) Or
                                                         charity.charityId.ToLower().Contains(name.ToLower())) And
                                                    (String.IsNullOrEmpty(referenceNumber) Or
                                                     charity.charityReference.ToLower().Contains(referenceNumber.ToLower()))
End Function

I got the same error in this code:

 var articulos_en_almacen = xx.IV00102.Where(iv => alm_x_suc.Exists(axs => axs.almacen == iv.LOCNCODE.Trim())).Select(iv => iv.ITEMNMBR.Trim()).ToList();

this was the exactly error:

System.NotSupportedException: 'LINQ to Entities does not recognize the method 'Boolean Exists(System.Predicate`1[conector_gp.Models.almacenes_por_sucursal])' method, and this method cannot be translated into a store expression.'

I solved this way:

var articulos_en_almacen = xx.IV00102.ToList().Where(iv => alm_x_suc.Exists(axs => axs.almacen == iv.LOCNCODE.Trim())).Select(iv => iv.ITEMNMBR.Trim()).ToList();

I added a .ToList() before my table, this decouple the Entity and linq code, and avoid my next linq expression be translated

NOTE: this solution isn't optimal, because avoid entity filtering, and simply loads all table into memory