PredicateBuilder可以生成跨多个表的谓词吗？
我想在Linq语句中动态生成跨多个表跨多个表的谓词。在下面的代码片段中，我想使用PredicateBuilder或类似的构造来替换以下代码中的'where'语句：
更换：
public class Foo
{
public int FooId; // PK
public string Name;
}
public class Bar
{
public int BarId; // PK
public string Description;
public int FooId; // FK to Foo.PK
}
void Test()
{
IQueryable<Foo> fooQuery = null; // Stubbed out
IQueryable<Bar> barQuery = null; // Stubbed out
IQueryable<Foo> query =
from foo in fooQuery
join bar in barQuery on foo.FooId equals bar.FooId
where ((bar.Description == "barstring") || (foo.Name == "fooname"))
select foo;
}
void Test(bool searchName, bool searchDescription)
{
IQueryable<Foo> fooQuery = null; // Stubbed out
IQueryable<Bar> barQuery = null; // Stubbed out
IQueryable<Foo> query =
from foo in fooQuery
join bar in barQuery on foo.FooId equals bar.FooId
select foo;
// OR THIS
var query =
from foo in fooQuery
join bar in barQuery on foo.FooId equals bar.FooId
select new {foo, bar};
var predicate = PredicateBuilder.False<Foo>();
if (searchName)
{
predicate = predicate.Or(foo => foo.Name == "fooname");
}
if (searchDescription)
{
// Cannot compile
predicate = predicate.Or(bar => bar.Description == "barstring");
}
// Cannot compile
query = query.Where(predicate);
}
没有找到相关结果
已邀请:
1 个回复
超可林
void Test() { IQueryable<Foo> fooQuery = null; // Stubbed out IQueryable<Bar> barQuery = null; // Stubbed out IQueryable<Foo> query = from foo in fooQuery join bar in barQuery on foo.FooId equals bar.FooId select new {Foo = foo, Bar = bar}; if (searchName) { query = query.Where(fb => fb.Foo.Name == "fooname"); } if (searchDescription) { query = query.Where(fb => fb.Bar.Description == "barstring"); } // use query here }class FooBar { public Foo Foo {get;set;} public Bar Bar {get;set;} } void Test(bool searchName, bool searchDescription) { IQueryable<Foo> fooQuery = null; // Stubbed out IQueryable<Bar> barQuery = null; // Stubbed out var query = from foo in fooQuery join bar in barQuery on foo.FooId equals bar.FooId select new FooBar { Foo = foo, Bar = bar }; var predicate = PredicateBuilder.False<FooBar>(); if (searchName) { predicate = predicate.Or(foobar => foobar.Foo.Name == "fooname"); } if (searchDescription) { predicate = predicate.Or(foobar => foobar.Bar.Description == "barstring"); } query = query.Where(predicate); // use query here }