C# Lambda 表达式中的多个 Where 子句
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Multiple Where clauses in Lambda expressions
提问by ashwnacharya
I have a simple lambda expression that goes something like this:
我有一个简单的 lambda 表达式，它是这样的：
x=> x.Lists.Include(l => l.Title).Where(l=>l.Title != String.Empty)
Now, if I want to add one more where clause to the expression, say, l.InternalName != String.Emptythen what would the expression be?
现在，如果我想在表达式中l.InternalName != String.Empty再添加一个 where 子句，那么表达式会是什么？
采纳答案by Rubens Farias
Can be
可
x => x.Lists.Include(l => l.Title)
.Where(l => l.Title != String.Empty && l.InternalName != String.Empty)
or
或者
x => x.Lists.Include(l => l.Title)
.Where(l => l.Title != String.Empty)
.Where(l => l.InternalName != String.Empty)
When you are looking at Whereimplementation, you can see it accepts a Func(T, bool); that means:
当您查看Where实现时，您可以看到它接受一个Func(T, bool); 这意味着：
Tis your IEnumerable typeboolmeans it needs to return a boolean value
T是您的 IEnumerable 类型bool意味着它需要返回一个布尔值
So, when you do
所以，当你做
.Where(l => l.InternalName != String.Empty)
// ^ ^---------- boolean part
// |------------------------------ "T" part
回答by Winston Smith
x=> x.Lists.Include(l => l.Title).Where(l=>l.Title != String.Empty).Where(l => l.Internal NAme != String.Empty)
or
或者
x=> x.Lists.Include(l => l.Title).Where(l=>l.Title != String.Empty && l.Internal NAme != String.Empty)
回答by Joey
Maybe
也许
x=> x.Lists.Include(l => l.Title)
.Where(l => l.Title != string.Empty)
.Where(l => l.InternalName != string.Empty)
?
?
You can probably also put it in the same where clause:
你也可以把它放在同一个 where 子句中：
x=> x.Lists.Include(l => l.Title)
.Where(l => l.Title != string.Empty && l.InternalName != string.Empty)
回答by Joey
You can include it in the same where statement with the && operator...
您可以使用 && 运算符将其包含在相同的 where 语句中...
x=> x.Lists.Include(l => l.Title).Where(l=>l.Title != String.Empty
&& l.InternalName != String.Empty)
You can use any of the comparison operators (think of it like doing an if statement) such as...
您可以使用任何比较运算符（将其视为执行 if 语句），例如...
List<Int32> nums = new List<int>();
nums.Add(3);
nums.Add(10);
nums.Add(5);
var results = nums.Where(x => x == 3 || x == 10);
...would bring back 3 and 10.
...会带回 3 和 10。
回答by AakashM
The lambda you pass to Wherecan include any normal C# code, for example the &&operator:
您传递给的 lambdaWhere可以包含任何普通的 C# 代码，例如&&运算符：
.Where(l => l.Title != string.Empty && l.InternalName != string.Empty)
