Linq动态查询没有填充集合

Question

private void OnSearchExecute(IQueryable<SurveySearchCriteria> query)
    {
        SurveySearchCriteria ssc=query.Where(a => a.CriteriaString == "LastName").SingleOrDefault();
        string format = ssc.WhereClause;
        string args= string.Format(".{0}("{1}")", SelectedSearchType, EnteredSearchCriteria);
        string returnval = string.Format(format, args);           


        ReadmissionTrackingApplication.Server.Services.SurveysDomainContext _context =
                                new ReadmissionTrackingApplication.Server.Services.SurveysDomainContext();
        EntityQuery<ReadmitPatientList> eq = _context.GetReadmitPatientListByCriteriaQuery(returnval);
       var lo= _context.Load<ReadmitPatientList>(eq);

使用这段代码，它不会填充我的low .entities。我有一种感觉，因为我没有使用回调，但查询在linqpad中工作得很好。

returnval= "PatientLastName.Contains("test")"，当我把它插入linqpad时，它工作了。

ReadmitPatientList.AsQueryable()。("PatientLastName.Contains("测试")")

这是domainservice查询…

public IQueryable<Data.ReadmitPatientList> GetReadmitPatientListByCriteria(string formattedCriteriaString)
        {
            var query = this.ObjectContext.ReadmitPatientList.AsQueryable()
                             .Where(a => a.OriginalAdmitDate >= new DateTime(2010, 01, 01))
                             .Where(formattedCriteriaString);
            return query;
        }

我的问题是为什么这是在linqpad工作，而不是在我的代码。我使用silverlight，所以它可能是因为没有回调。这是我第一次尝试基于web的编程，所以我还在适应所有的复杂性…

Answer 1

这是一个回调问题。我重构了我的代码，以便它实现回调功能，并清理了Domainservice调用，现在它可以工作了。

客户服务:

public void getReadmitPatientList(System.Action<ICollection<ReadmitPatientList>> callback, string searchCriteria)
        {
            var q = _context.GetReadmitPatientListByCriteriaQuery(searchCriteria);
            _context.Load<ReadmitPatientList>(q, OnReamitPatientListLoaded, callback);
        }
        public void getReadmitPatientList(System.Action<ICollection<ReadmitPatientList>> callback, int days)
        {
            DateTime CurrentDate = DateTime.Today;
            DateTime entryDate = CurrentDate.AddDays(-days);
            var q = _context.GetReadmitPatientListQuery().Where(a => a.OriginalAdmitDate >= entryDate);
            _context.Load<ReadmitPatientList>(q, OnReamitPatientListLoaded, callback);
        }
        public void OnReamitPatientListLoaded(LoadOperation<ReadmitPatientList> lo)
        {
            if (!lo.HasError)
            {
                ICollection<ReadmitPatientList> q = new ObservableCollection<ReadmitPatientList>(lo.Entities);
                var action = (Action<ICollection<ReadmitPatientList>>)lo.UserState;
                action.Invoke(q);
            }
            else
            {
                MessageBox.Show(string.Format("{1}{0}{2}", Environment.NewLine, lo.Error.Message, lo.Error.InnerException));
                lo.MarkErrorAsHandled();
            }
        }

域服务:

 public IQueryable<Data.ReadmitPatientList> GetReadmitPatientListByCriteria(string formattedCriteriaString)
    {
        var query = this.ObjectContext.ReadmitPatientList.AsQueryable()
                         .Where(a => a.OriginalAdmitDate >= new DateTime(2010, 01, 01))
                         .Where(formattedCriteriaString);
        return query;
    }