linq (to nHibernate): 'like in' operator

问题

Hi
Given a list of strings I want to retrieve all items whose names contain one of the given strings.
for example- given {"foo", "kuku"} I want to retrieve the employees "Corfoo", "kuku maluku" and "kukufoo".
I've tried the following, but got a null-reference exception(?)

query.Where(u => values.Any(v=> u.FullName.Contains(v)) );

The following produced a 'Lambda expression not in scope' exception.

query.Where(u => (values.Count(v => u.FullName.Contains(v)) > 0) );

any idea how this can be done?
I was thinking along the lines of iterating over the values collection and adding a new condition for each element.
problem is- the .Where() function is a conjunction (AND) and I need disjunction (OR)...
(I'm using nH 2.1.2 with Linq provider; hadn't tried this on nH3.0 yet...)

回答1:

If you are not limited to the Linq provider but also open to the ICriteria API, I suggest using the following:

List<string> fullnames = new List<string>() { "foo", "kuku" };
// prepare Query
var query = session.CreateCriteria(typeof(Employee));
// dynamically add Like-conditions combined with OR
Disjunction namesCriteria = Restrictions.Disjunction();
foreach (var name in fullnames)
{
    namesCriteria.Add(Restrictions.Like("FullName", name, MatchMode.Anywhere));
}
// add complete Disjunction to prepared query
query.Add(namesCriteria);
IList<Employee> list = query.List<Employee>();

I think trying that in NHibernate.Linq might be harder if not impossible. With NH 3.0 you could use QueryOver, which would get rid of the magic strings.

回答2:

I Used the following code hope it helps;

   public IList<AutoCompleteDto> GetCitiesLike(string text)
    {
        AutoCompleteDto autoCompleteDto = null;

        var cityList = UnitOfWork.CurrentSession.QueryOver<City>()
            .Where(x => x.CityName.IsLike(text, MatchMode.Start))
            .SelectList(u => u
                                 .Select(x => x.Id).WithAlias(() => autoCompleteDto.Id)
                                 .Select(x => x.CityName).WithAlias(() => autoCompleteDto.Name)
                                 .Select(x => x.CityName).WithAlias(() => autoCompleteDto.Value))
            .TransformUsing(Transformers.AliasToBean<AutoCompleteDto>())
            .List<AutoCompleteDto>();


        return cityList;
    }

回答3:

i used the following coding styles

QueryOver

IQueryOver<Patient> rowCount = Session.QueryOver<Patient>().ToRowCountQuery();

                    IQueryOver<Patient> result = this.Session.QueryOver<Patient>()
                     .Where(p => (p.FullNameEn.IsLike("%" + criteria.Keyword.Replace(" ", "%") + "%"))
                         || (p.FullNameAr.IsLike("%" + criteria.Keyword.Replace(" ", "%") + "%"))
                         || (p.IdentityNO == criteria.Keyword)
                         || (p.MobileNO == criteria.Keyword)
                         || (p.PatientID == patientIDKeyword)
                      )
                      .OrderBy(p => p.FullNameEn).Asc
                      .Take(criteria.PageSize)
                      .Skip((criteria.Page - 1) * criteria.PageSize);


                    totalCount = result.ToRowCountQuery().FutureValue<int>().Value;
                    transaction.Commit();
                    return result.Future<Patient>().ToList();

LINQ

var query = this.LINQ;
query = query.Where(p => p.VendorNameAr.Contains(criteria.Keyword.Replace(" ", "%")) ||
                                             p.VendorNameEN.Contains(criteria.Keyword.Replace(" ", "%")));
return query.ToList();

来源：https://stackoverflow.com/questions/5487057/linq-to-nhibernate-like-in-operator

标签

linq

nhibernate

linq-to-nhibernate