我第一次使用LINQ查询进入表达式树时遇到了困难 . 这是没有表达式树的查询:
IQueryable<SampleResult> samples = samples.Select(a => new
{
a = a,
innerQuery = _dc.RequestedTests
.SelectMany(
b => _dc.ResultData.Where(x => (x.TestNum == b.TestNum && b.SampleID == a.SampleID))
.DefaultIfEmpty(),
(b, c) => new RequestedTestsJoinedResultData
{
RequestedTests = b,
ResultData = c
}).Where(joinedTable => ((joinedTable.ResultData.ResultID == 1) &&
(joinedTable.RequestedTests.TestID == 38) &&
(joinedTable.ResultData.IntValue >= (Int32?) 90))
).Select(joinedTable => joinedTable.RequestedTests.SampleID)
}).Where(temp0 => temp0.innerQuery.Contains(temp0.a.SampleID)).Select(temp0 => temp0.a);
我的下一步是构建一个表达式树,以发送到中间的 Where()
调用 . 需要表达式树来根据用户输入动态创建过滤器 .
var joinedTableParameter = Expression.Parameter(typeof(RequestedTestsJoinedResultData),
"joinedTable");
var left = Expression.Property(joinedTableParameter,
typeof(RequestedTestsJoinedResultData).GetProperty("ResultData"));
left = Expression.Property(left,
typeof(ResultData).GetProperty("ResultID"));
var rightConstant = Expression.Constant(resultFilter.ResultID);
Expression e1 = Expression.Equal(left, rightConstant);
left = Expression.Property(joinedTableParameter, typeof(RequestedTestsJoinedResultData)
.GetProperty("RequestedTests"));
left = Expression.Property(left, typeof(RequestedTests)
.GetProperty("TestID"));
rightConstant = Expression.Constant(resultFilter.TestID);
Expression e2 = Expression.Equal(left, rightConstant);
var preditcateBody = Expression.AndAlso(e1, e2);
left = Expression.Property(joinedTableParameter, typeof(RequestedTestsJoinedResultData)
.GetProperty("ResultData"));
left = Expression.Property(left, typeof(ResultData)
.GetProperty(comparisonColumn));
rightConstant = Expression.Constant(resultFilter.ResultValue, type);
Expression e3 = Expression.MakeBinary(resultFilter.ResultComparison,
left, rightConstant);
preditcateBody = Expression.AndAlso(preditcateBody, e3);
var lambda = Expression.Lambda<Func<RequestedTestsJoinedResultData, bool>>
(preditcateBody, joinedTableParameter);
然后第一个代码块从此更改:
.Where(joinedTable => ((joinedTable.ResultData.ResultID == 1) &&
(joinedTable.RequestedTests.TestID == 38) &&
(joinedTable.ResultData.IntValue >= (Int32?)90))
对此:
.Where(lambda)
第一个代码块作为 IQueryable
工作,但是当使用表达式树,第二个代码块时,它只有在我将其更改为 IEnumerable
时才有效 . 使用 IQueryable
时出现此运行时错误:
System.Data.Linq.dll中出现“System.NotSupportedException”类型的异常但未在用户代码中处理其他信息:用于查询运算符“Where”的不支持的重载 .
堆栈跟踪:
在System.Data.Linq.SqlClient的System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc)\ r \ n,在System.Data.Linq.SqlClient的System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node)\ r \ n中 . System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq上的System.Data.Linq.SqlClient.SqlProvider.BuildQuery(表达式查询,SqlNodeAnnotations注释)\ r \ n的QueryConverter.ConvertOuter(表达式节点)\ r \ n System.Linq.SystemCore_EnumerableDebugView1.get_Items上的System.Data.Linq.DataQuery1.System.Collections.Generic.IEnumerable <T> .GetEnumerator()\ r \ n的.Provider.IProvider.Execute(表达式查询)\ r \ n( )”
EDITS:
1:我的自定义数据模型类:
public class RequestedTestsJoinedResultData
{
public virtual RequestedTests RequestedTests { get; set; }
public virtual ResultData ResultData { get; set; }
}
2:lambdas的DebugView:
从表达式树创建的where子句lambda dynamically :
.Lambda #Lambda1<System.Func`2[SoDak.Domain.Models.RequestedTestsJoinedResultData,System.Boolean]>
(SoDak.Domain.Models.RequestedTestsJoinedResultData $joinedTable)
($joinedTable.ResultDataTable).ResultID == 1 &&
($joinedTable.RequestedTestsTable).TestID == 38 &&
($joinedTable.ResultDataTable).IntValue >=
.Constant<System.Nullable`1[System.Int32]>(90)
带有 hard coded 结果过滤器的大型lambda:
.Call System.Linq.Queryable.Select(.Call System.Linq.Queryable.Where(
.Call System.Linq.Queryable.Select(.Call System.Linq.Queryable.Select(
.Call System.Linq.Queryable.Where( .Call System.Linq.Queryable.Select(
.Call System.Linq.Queryable.SelectMany( .Call System.Linq.Queryable.Where(
.Constant(Table(Samples)), '(.Lambda #Lambda1)), '(.Lambda #Lambda2),
'(.Lambda #Lambda3)), '(.Lambda #Lambda4f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]]]>)) ,
'(.Lambda #Lambda5f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],System.Boolean]>)) ,
'(.Lambda #Lambda6f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],SoDak.Domain.Models.SampleResult]>)) ,
'(.Lambda #Lambda7f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]]]>)) ,
'(.Lambda #Lambda8f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],System.Boolean]>)) ,
'(.Lambda #Lambda9f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],SoDak.Domain.Models.SampleResult]>))
.Lambda #Lambda1(SoDak.Domain.Samples $a) {
($a.StatusID == (System.Nullable`1[System.Int32])3 ||
$a.StatusID == (System.Nullable`1[System.Int32])4) &&
$a.Lab == .Constantc__DisplayClass24_0>(SoDak.Domain.Services.SampleService+<>c__DisplayClass24_0).labID }
.Lambda #Lambda2(SoDak.Domain.Samples $a) {
.Call System.Linq.Queryable.DefaultIfEmpty(
.Call System.Linq.Queryable.Where( (.Constant(SoDak.Domain.Services.SampleService)._dc).CustomFields, '(.Lambda #Lambda10)))
}
.Lambda #Lambda3( SoDak.Domain.Samples $a, SoDak.Domain.CustomFields $b) {
.New SoDak.Domain.Models.SampleResult(){
LabCount = (System.Int32)$a.LabCount, SampleID = $a.SampleID,
AccountID = (System.Int32)$a.AccountID,Received = (System.Nullable`1[System.DateTime])(($a.Received).Value).Date,
Completed = (System.Nullable`1[System.DateTime])(($a.Completed).Value).Date,
SpeciesID = (System.Nullable`1[System.Int32])$a.SpeciesID,
SpeciesCommonName = ($a.SeedNames).CommonName,StatusID = (System.Int32)$a.StatusID,
StatusName = ($a.SampleStatus).StatusName,Variety = $a.Variety,Lot = $a.Lot,
CarryOver = $a.CarryOver,Lab = (System.Int32)$a.Lab,LabID = (System.Int32)$a.Lab,
TestList = $a.TestList,CustomFieldName = $b.CustomFieldName,CustomFieldNameValue = $b.CustomFieldNameValue
}
} .Lambda #Lambda4f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]]]>(SoDak.Domain.Models.SampleResult $a) {
.New <>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]](
$a, .Call System.Linq.Queryable.Select( .Call System.Linq.Queryable.Where( (.Constant(SoDak.Domain.Services.SampleService)._dc).SubAccounts,
'(.Lambda #Lambda11)), '(.Lambda #Lambda12))) }
.Lambda #Lambda5f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],
System.Boolean]>(<>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,
System.Linq.IQueryable`1[System.Int32]] $<>h__TransparentIdentifier0) {
($<>h__TransparentIdentifier0.a).AccountID == .Constantc__DisplayClass24_0>(SoDak.Domain.Services.SampleService+<>c__DisplayClass24_0).accountIDLoggedIn ||
.Call System.Linq.Queryable.Contains( $<>h__TransparentIdentifier0.innerQuery,
.Constantc__DisplayClass24_0>(SoDak.Domain.Services.SampleService+<>c__DisplayClass24_0).accountIDLoggedIn) }
.Lambda #Lambda6f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],
SoDak.Domain.Models.SampleResult]>(<>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]] $<>h__TransparentIdentifier0) {
$<>h__TransparentIdentifier0.a } .Lambda #Lambda7f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]]]>(
SoDak.Domain.Models.SampleResult $a) { .New <>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]](
$a, .Call System.Linq.Queryable.Select( .Call System.Linq.Queryable.Where( .Call System.Linq.Queryable.SelectMany(
(.Constant(SoDak.Domain.Services.SampleService)._dc).RequestedTests, '(.Lambda #Lambda13), '(.Lambda #Lambda14)) , '(.Lambda #Lambda15)), '(.Lambda #Lambda16))) }
.Lambda #Lambda8f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],System.Boolean]>(<>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]] $temp0) {
.Call System.Linq.Queryable.Contains( $temp0.innerQuery, ($temp0.a).SampleID) }
.Lambda #Lambda9f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],SoDak.Domain.Models.SampleResult]>(<>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]] $temp0) { $temp0.a }
.Lambda #Lambda10(SoDak.Domain.CustomFields $x) {
$x.SampleID == $a.SampleID && $x.OnReport == (System.Nullable`1[System.Boolean])True } .Lambda #Lambda11(SoDak.Domain.SubAccounts $b) {
$b.SampleID == $a.SampleID } .Lambda #Lambda12(SoDak.Domain.SubAccounts $b) { $b.AccountID } .Lambda #Lambda13(SoDak.Domain.RequestedTests $b) {
.Call System.Linq.Queryable.DefaultIfEmpty(.Call System.Linq.Queryable.Where( (.Constant(SoDak.Domain.Services.SampleService)._dc).ResultData, '(.Lambda #Lambda17))) }
.Lambda #Lambda14( SoDak.Domain.RequestedTests $b, SoDak.Domain.ResultData $c) { .New SoDak.Domain.Models.RequestedTestsJoinedResultData(){
RequestedTestsTable = $b, ResultDataTable = $c } } .Lambda #Lambda15(SoDak.Domain.Models.RequestedTestsJoinedResultData $joinedTable) {
$joinedTable != null && ($joinedTable.ResultDataTable).ResultID == 1 && ($joinedTable.RequestedTestsTable).TestID == 38 && ($joinedTable.ResultDataTable).IntValue >= (System.Nullable`1[System.Int32])90 }
.Lambda #Lambda16(SoDak.Domain.Models.RequestedTestsJoinedResultData $joinedTable) { ($joinedTable.RequestedTestsTable).SampleID }
.Lambda #Lambda17(SoDak.Domain.ResultData $x) { $x.TestNum == $b.TestNum && $b.SampleID == $a.SampleID }
带有 dynamically created 结果的大型lambda通过表达式树构建过滤 .
.Call System.Linq.Queryable.Select(
.Call System.Linq.Queryable.Where(
.Call System.Linq.Queryable.Select(
.Call System.Linq.Queryable.Select(
.Call System.Linq.Queryable.Where(
.Call System.Linq.Queryable.Select(
.Call System.Linq.Queryable.SelectMany(
.Call System.Linq.Queryable.Where(
.Constant(Table(Samples)),
'(.Lambda #Lambda1)), '(.Lambda #Lambda2), '(.Lambda #Lambda3)),
'(.Lambda #Lambda4f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]]]>)) ,
'(.Lambda #Lambda5f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],System.Boolean]>)) ,
'(.Lambda #Lambda6f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],SoDak.Domain.Models.SampleResult]>)) ,
'(.Lambda #Lambda7f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]]]>)) ,
'(.Lambda #Lambda8f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],System.Boolean]>)) ,
'(.Lambda #Lambda9f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],SoDak.Domain.Models.SampleResult]>))
.Lambda #Lambda1(SoDak.Domain.Samples $a) { ($a.StatusID == (System.Nullable`1[System.Int32])3 || $a.StatusID == (System.Nullable`1[System.Int32])4) &&
$a.Lab == .Constantc__DisplayClass24_0>(SoDak.Domain.Services.SampleService+<>c__DisplayClass24_0).labID }
.Lambda #Lambda2(SoDak.Domain.Samples $a) {
.Call System.Linq.Queryable.DefaultIfEmpty(.Call System.Linq.Queryable.Where( (.Constant(SoDak.Domain.Services.SampleService)._dc).CustomFields, '(.Lambda #Lambda10))) }
.Lambda #Lambda3( SoDak.Domain.Samples $a, SoDak.Domain.CustomFields $b) {
.New SoDak.Domain.Models.SampleResult(){
LabCount = (System.Int32)$a.LabCount,
SampleID = $a.SampleID, AccountID = (System.Int32)$a.AccountID,
Received = (System.Nullable`1[System.DateTime])(($a.Received).Value).Date,
Completed = (System.Nullable`1[System.DateTime])(($a.Completed).Value).Date,
SpeciesID = (System.Nullable`1[System.Int32])$a.SpeciesID,
SpeciesCommonName = ($a.SeedNames).CommonName,StatusID = (System.Int32)$a.StatusID,
StatusName = ($a.SampleStatus).StatusName,Variety = $a.Variety, Lot = $a.Lot,
CarryOver = $a.CarryOver,Lab = (System.Int32)$a.Lab,LabID = (System.Int32)$a.Lab,
TestList = $a.TestList,CustomFieldName = $b.CustomFieldName,CustomFieldNameValue = $b.CustomFieldNameValue } }
.Lambda #Lambda4f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]]]>(SoDak.Domain.Models.SampleResult $a) {
.New <>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]](
$a,
.Call System.Linq.Queryable.Select(
.Call System.Linq.Queryable.Where( (.Constant(SoDak.Domain.Services.SampleService)._dc).SubAccounts,
'(.Lambda #Lambda11)), '(.Lambda #Lambda12))) }
.Lambda #Lambda5f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],System.Boolean]>
(<>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]] $<>h__TransparentIdentifier0) {
($<>h__TransparentIdentifier0.a).AccountID == .Constantc__DisplayClass24_0>(SoDak.Domain.Services.SampleService+<>c__DisplayClass24_0).accountIDLoggedIn ||
.Call System.Linq.Queryable.Contains( $<>h__TransparentIdentifier0.innerQuery, .Constantc__DisplayClass24_0>(SoDak.Domain.Services.SampleService+<>c__DisplayClass24_0).accountIDLoggedIn) }
.Lambda #Lambda6f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],SoDak.Domain.Models.SampleResult]>(<>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]] $<>h__TransparentIdentifier0) { $<>h__TransparentIdentifier0.a }
.Lambda #Lambda7f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]]]>(SoDak.Domain.Models.SampleResult $a) { .New <>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]](
$a, .Call System.Linq.Queryable.Select(
.Call System.Linq.Queryable.Where(
.Call System.Linq.Queryable.SelectMany( (.Constant(SoDak.Domain.Services.SampleService)._dc).RequestedTests,
'(.Lambda #Lambda13), '(.Lambda #Lambda14)) ,
.Constantc__DisplayClass24_1>(SoDak.Domain.Services.SampleService+<>c__DisplayClass24_1).lambda) ,
'(.Lambda #Lambda15))) } .Lambda #Lambda8f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],System.Boolean]>(<>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]] $temp0) {
.Call System.Linq.Queryable.Contains( $temp0.innerQuery, ($temp0.a).SampleID) }
.Lambda #Lambda9f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]],SoDak.Domain.Models.SampleResult]>(<>f__AnonymousType1`2[SoDak.Domain.Models.SampleResult,System.Linq.IQueryable`1[System.Int32]] $temp0) {
$temp0.a }
.Lambda #Lambda10(SoDak.Domain.CustomFields $x) {
$x.SampleID == $a.SampleID && $x.OnReport == (System.Nullable`1[System.Boolean])True }
.Lambda #Lambda11(SoDak.Domain.SubAccounts $b) { $b.SampleID == $a.SampleID }
.Lambda #Lambda12(SoDak.Domain.SubAccounts $b) { $b.AccountID }
.Lambda #Lambda13(SoDak.Domain.RequestedTests $b) {
.Call System.Linq.Queryable.DefaultIfEmpty(.Call System.Linq.Queryable.Where( (.Constant(SoDak.Domain.Services.SampleService)._dc).ResultData, '(.Lambda #Lambda16))) }
.Lambda #Lambda14( SoDak.Domain.RequestedTests $b, SoDak.Domain.ResultData $c) {
.New SoDak.Domain.Models.RequestedTestsJoinedResultData(){ RequestedTestsTable = $b, ResultDataTable = $c } }
.Lambda #Lambda15(SoDak.Domain.Models.RequestedTestsJoinedResultData $joinedTable) {
($joinedTable.RequestedTestsTable).SampleID }
.Lambda #Lambda16(SoDak.Domain.ResultData $x) { $x.TestNum == $b.TestNum && $b.SampleID == $a.SampleID }
3:我继续使用System.Linq.Dynamic尝试相同的查询,并得到了另一个可能相关或不相关的错误 .
使用动态LINQ的where子句:
.Where("joinedTable => " +
"((joinedTable.ResultDataTable.ResultID == " + resultFilter.ResultID + ") && " +
"(joinedTable.RequestedTestsTable.TestID == " + resultFilter.TestID + ") && " +
"(joinedTable.ResultDataTable." + resultFilter.ResultType + " >= " +
resultFilter.ResultValueString + "))")
错误:
成员访问'SoDak.Domain.Models.RequestedTestsJoinedResultData'的'SoDak.Domain.RequestedTests RequestedTestsTable'在类型'System.Linq.IQueryable`1 [SoDak.Domain.Models.RequestedTestsJoinedResultData]上不合法 .
4:结果过滤器硬编码时生成的SQL:
SELECT [t4].[SampleID], [t4].[value] AS [LabCount], [t4].[value2] AS [Lab], [t4].[value3] AS [LabID], [t4].[value4] AS [AccountID], [t4].[value5] AS [Received], [t4].[value6] AS [Completed], [t4].[value7] AS [SpeciesID], [t4].[CommonName] AS [SpeciesCommonName], [t4].[value8] AS [StatusID], [t4].[StatusName], [t4].[Variety], [t4].[Lot], [t4].[CarryOver], [t4].[TestList], [t4].[value9] AS [CustomFieldName], [t4].[value10] AS [CustomFieldNameValue]
FROM (
SELECT [t0].[SampleID], [t0].[LabCount] AS [value], [t0].[Lab] AS [value2], [t0].[Lab] AS [value3], [t0].[AccountID] AS [value4], CONVERT(DATE, [t0].[Received]) AS [value5], CONVERT(DATE, [t0].[Completed]) AS [value6], [t0].[SpeciesID] AS [value7], [t2].[CommonName], [t0].[StatusID] AS [value8], [t3].[StatusName], [t0].[Variety], [t0].[Lot], [t0].[CarryOver], [t0].[TestList], [t1].[CustomFieldName] AS [value9], [t1].[CustomFieldNameValue] AS [value10], [t0].[StatusID], [t0].[Lab]
FROM [Samples].[Samples] AS [t0]
LEFT OUTER JOIN [Web].[CustomFields] AS [t1] ON ([t1].[SampleID] = [t0].[SampleID]) AND ([t1].[OnReport] = @p0)
INNER JOIN [Seeds].[SeedNames] AS [t2] ON [t2].[SpeciesID] = [t0].[SpeciesID]
LEFT OUTER JOIN [Lookup].[SampleStatus] AS [t3] ON [t3].[StatusID] = [t0].[StatusID]
) AS [t4]
WHERE (EXISTS(
SELECT NULL AS [EMPTY]
FROM [Samples].[RequestedTests] AS [t5]
LEFT OUTER JOIN [Results].[ResultData] AS [t6] ON ([t6].[TestNum] = [t5].[TestNum]) AND ([t5].[SampleID] = [t4].[SampleID])
WHERE ([t5].[SampleID] = [t4].[SampleID]) AND ([t6].[ResultID] = @p1) AND ([t5].[TestID] = @p2) AND ([t6].[IntValue] >= @p3)
)) AND (([t4].[value4] = @p4) OR (EXISTS(
SELECT NULL AS [EMPTY]
FROM [Samples].[SubAccounts] AS [t7]
WHERE ([t7].[AccountID] = @p5) AND ([t7].[SampleID] = [t4].[SampleID])
))) AND (([t4].[StatusID] = @p6) OR ([t4].[StatusID] = @p7)) AND ([t4].[Lab] = @p8)
它是真的不受支持还是我在构建表达式树时做错了什么?
2 回答
Short answer:
我认为绊倒你的是你对可空过滤器的处理 . 如果你围绕一个可以为空的double(或int)包装一个
Expression.Constant
,我不确定它会很好地编译 .这是lambdas漂亮打印的两个DebugView:
Long answer
Hard coded
Dynamic with the lambda at the end
如果你对这两个文本墙进行区分,你会发现它们几乎完全相同 . lambda的编号变化无关紧要 . 有几件事突然冒出来:
在动态方面,lambda包含在一个闭包中 . 最好确保不重复使用变量
lambda
. 如果是,那将影响你的表达 .硬编码侧有空检查,动态侧没有 .
看起来对于最后的比较,硬编码方将比较
.IntValue
转换为int?
,动态方传递常量int?
. 我认为这是你问题的根源 .我最终打破了复杂的内部查询,这解决了我的问题 . 使用
IEnumerable
并对整个ResultData
表进行过滤超过90秒 . 让IQueryable
工作后降低到不到0.5秒 .您将需要解读上面原始帖子的顶部部分,以查看我从那里到此处的更改 .