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我有一张要过滤的表格。有一个过滤器过滤值“包括”，它可以是真或假。

我有一个过滤器，它有 3 个选项：true、false和all。

因此，当过滤器为真时，它应该返回行 where include = 'true'; 当过滤器为 'false' 时，返回 where include = false; 当“全部”返回其中 include = true 或 false 时。

这是我的代码，它不起作用，但我认为它应该是。

private ICollection<AggregationEntityViewModel> getEntities(AggregationPracticeDetailsViewModel apdvm)
{
    bool? filterInclude = Convert.ToBoolean(apdvm.Filter_IncludeValue);

    var a = (from e in _repository.GetAll<Entity>()                         
        where e.include == filterInclude != null ? (bool)filterInclude : (true || false)                     
        select e
     return a;
}

当过滤器设置为“全部”或“假”时，它当前返回 0 行，设置为“是”时返回所有行。

仅供参考，为了清楚起见，我省略了很多代码。

请帮助...谢谢！

*编辑：我已经显示了所有代码，所以你可以看到为什么我想把它全部保留在 linq 查询中。感谢您提供的所有解决方案。我看到大多数解决方案都涉及使用 Linq 扩展方法。无论如何在内联linq查询中这样做？* 

bool? filterInclude = Convert.ToBoolean(apdvm.Filter_IncludeValue);
            var a = (from e in _repository.GetAll<Entity>()
                     from u in e.Users
                     where (e.AuditQuestionGroupId != null ? e.AuditQuestionGroupId : 0) == this.LoggedInEntity.AuditQuestionGroupId
                     && e.BatchNumber != null && e.BatchNumber.StartsWith(apdvm.Filter_BatchNumber == null ? "" : apdvm.Filter_BatchNumber)
                     && e.Name != null && e.Name.ToLower().StartsWith(apdvm.Filter_EntityName.ToLower())
                     && e.EntityState != null && e.EntityState.ToLower().Contains(apdvm.Filter_StateValue == null ? "" : apdvm.Filter_StateValue.ToLower())
                     && u.NIAMembershipId != null && u.NIAMembershipId.Contains(apdvm.Filter_MemberNo == null ? "" : apdvm.Filter_MemberNo)
                     from p in e.PracticeProfiles.DefaultIfEmpty()
                     join ea in _repository.GetAll<EntityAggregate>() on e.EntityId equals ea.EntityId into eas
                     from ea in eas.DefaultIfEmpty()                     
                     where ea.include == filterInclude != null ? (bool)filterInclude : (true || false)
                     group e by new { entity = e, profile = p, ea = ea } into newGroup
                     orderby newGroup.Key.entity.Name
                     select new AggregationEntityViewModel()
                     {
                         Id = newGroup.Key.ea == null ? 0 : newGroup.Key.ea.Id,
                         EntityId = newGroup.Key.entity.EntityId,
                         Include = newGroup.Key.ea == null ? (true || false) : (bool)newGroup.Key.ea.include,
                         BHAddress = newGroup.Key.profile == null || newGroup.Key.profile.soloOffice == null ? false : (bool)newGroup.Key.profile.soloOffice,
                         Incorporated = newGroup.Key.profile == null || newGroup.Key.profile.company == null ? false : (bool)newGroup.Key.profile.company,
                         MajorityOwned = newGroup.Key.profile == null || newGroup.Key.profile.capital == null ? false : (bool)newGroup.Key.profile.capital,
                         MajorityVoting = newGroup.Key.profile == null || newGroup.Key.profile.votingRights == null ? false : (bool)newGroup.Key.profile.votingRights,
                         Name = newGroup.Key.entity.Name,
                         Partnership = newGroup.Key.profile == null || newGroup.Key.profile.partnership == null ? false : (bool)newGroup.Key.profile.partnership,
                         PublicAccountant = newGroup.Key.profile == null || newGroup.Key.profile.publicAccountant == null ? false : (bool)newGroup.Key.profile.publicAccountant,
                         Trust = newGroup.Key.profile == null || newGroup.Key.profile.operatingTrust == null ? false : (bool)newGroup.Key.profile.operatingTrust,
                         TrustDeed = newGroup.Key.profile == null || newGroup.Key.profile.deed == null ? false : (bool)newGroup.Key.profile.deed
                     }).ToList();
            return a;
4

4 回答 4

4

  1. Convert.ToBoolean回报bool，没有bool?，所以没有办法filterInclude != null是true。

  2. where您应该在子句中使用以下模式而不是三元运算符：

    var query = _repository.GetAll<Entity>();

if (apdvm.Filter_IncludeValue == "true")
    query = query.Where(x => x.include == true);
else if (apdvm.Filter_IncludeValue == "false")
    query = query.Where(x => x.include == false);

return query;

    我假设apdvm.Filter_IncludeValue是一个字符串（这就是你试图调用Convert.ToBoolean它的原因）。

于 2014-08-12T06:24:42.670 回答
1

还有一个解决方案：

var query = from e in _repository.GetAll<Entity>();

if (filterInclude.HasValue)
{

    // when filterInclude is null (it means **ALL**), 
    // do not filter otherwise - check the flag
    query = query.Where(entity => entity.Include == filterInclude.Value);
}

// or one-line:
// query = query.Where(entity => filterInclude == null
//                      || entity.Include == filterInclude.Value);

var a = query.Select(entity => new AggregationEntityViewModel { .... });

return a;

另一个问题是Convert.ToBoolean永远不会返回null。您应该创建自己的方法来解析apdvm.Filter_IncludeValue.

为了转换为可空类型，您可以使用泛型方法：

public static Nullable<T> ToNullable<T>(this string s) where T: struct
{
    Nullable<T> result = new Nullable<T>();
    try
    {
        if (!string.IsNullOrEmpty(s) && s.Trim().Length > 0)
        {
            TypeConverter conv = TypeDescriptor.GetConverter(typeof(T));
            result = (T)conv.ConvertFrom(s);
        }
    }
    catch { } 
    return result;
}

资源。

用法：

var filterInclude = apdvm.Filter_IncludeValue.ToNullable<bool>();
于 2014-08-12T06:24:54.303 回答
1

你可以使用

private ICollection<AggregationEntityViewModel> getEntities(
              AggregationPracticeDetailsViewModel apdvm)
{
    bool? filterInclude = apdvm.Filter_IncludeValue.ConvertToNullable<bool>();

    var a = (from e in _repository.GetAll<Entity>()                         
             where !filterInclude.HasValue || ea.include == filterInclude.Value                     
             select new AggregationEntityViewModel()
             {
                Include = newGroup.Key.ea == null 
                          ? (true || false) 
                          : (bool)newGroup.Key.ea.include,
             }
    return a;
}

只需删除你的(true||false)并添加filterInclude == null在哪里

对于 Nullable 值（取自Convert string to nullable type (int, double, etc...)）

public static T? ConvertToNullable<T>(this String s) where T : struct 
{
    try
    {
        return (T?)TypeDescriptor.GetConverter(typeof(T)).ConvertFrom(s);
    }
    catch (Exception)
    {
        return null;
    }
}
于 2014-08-12T06:23:34.990 回答
1

您可以使用如下流利的语法使其更容易：

private ICollection<AggregationEntityViewModel> getEntities(AggregationPracticeDetailsViewModel apdvm)
{
    var query = _repository.GetAll<Entity>();
    if(apdvm.Filter_IncludeValue != 'all')
    {
        var value = Convert.ToBoolean(apdvm.Filter_IncludeValue);
        query = query.Where(q => q.include == value)
    }
    return query.Select(q => new AggregationEntityViewModel {...}).ToArray();
}

无需将字符串评估为可为空的 bool 或 smth。就像不需要做奇怪的布尔表达式一样。

于 2014-08-12T06:26:55.573 回答