LINQ查询与条件WHERE子句 [英] Linq query with a Conditional WHERE Clause

问题描述

我是新来的LINQ等等道歉前期

我有以下的LINQ查询： -

<$ P $从上a.BranchKey AllBranchKeys
A在AllOrders
JOIN b p> VAR OrdersByBranches =
等于b.BranchKey
排序依据a.Date $ b $通过新的{a.Date，a.paymentMethod}成BranchOrderGrouped
b组选择新的
{
BranchOrderGrouped.Key.Date，
CurrencyAmount = BranchOrderGrouped.Sum（A => ;
a.CurrencyAmount），
BranchOrderGrouped.Key.paymentMethod
};


我需要包括在上面的查询where子句......只有一个变量被称为
BranchKeySelected是

我已经使用If Else语句尝试和有一个包含where子句和一个不能与
1个重复上述相同的查询。 ......但是，当我做到这一点..然后OrdersByBranches
不是if语句外提供

会感谢任何帮助

问候

鬼

解决方案

从上a.BranchKey AllBranchKeys一个在AllOrders 
 JOIN b  VAR OrdersByBranches = 
等于b.BranchKey 
排序依据a.Date 
通过新的{a.Date，a.paymentMethod}成BranchOrderGrouped 
组中选择新的{
 BranchOrderGrouped.Key.Date，
 CurrencyAmount = BranchOrderGrouped.Sum（A => a.CurrencyAmount） ，
 BranchOrderGrouped.Key.paymentMethod 
}; 
 
如果（string.IsNullOrEmpty（BranchKeySelected））
 {
 OrdersByBranches = OrdersByBranches.Where（/ * * blbabla /）; 
} 
 
返回OrdersByBranches; 
  

I am new to LINQ so apologises upfront

I have the following Linq query :-

var OrdersByBranches =
    from a in AllOrders
    join b in AllBranchKeys
        on a.BranchKey equals b.BranchKey
    orderby a.Date
    group a by new { a.Date, a.paymentMethod } into BranchOrderGrouped
    select new
    {
        BranchOrderGrouped.Key.Date,
        CurrencyAmount = BranchOrderGrouped.Sum(a =>
        a.CurrencyAmount),
        BranchOrderGrouped.Key.paymentMethod
    };

I need to include a where clause in the above query ... only if a variable called BranchKeySelected is ""

I have tried using an If Else statement and have the same above query duplicated with one containing a where clause and one NOT. ...But When I do this .. then OrdersByBranches is NOT available outside of the IF Statement

Would be grateful for any help

Regards

Ghost

解决方案

var OrdersByBranches = 
    from a in AllOrders 
    join b in AllBranchKeys on a.BranchKey equals b.BranchKey 
    orderby a.Date 
    group a by new { a.Date, a.paymentMethod } into BranchOrderGrouped 
    select new { 
        BranchOrderGrouped.Key.Date, 
        CurrencyAmount = BranchOrderGrouped.Sum(a =>  a.CurrencyAmount), 
        BranchOrderGrouped.Key.paymentMethod 
    };

if(string.IsNullOrEmpty(BranchKeySelected ))
{
    OrdersByBranches = OrdersByBranches.Where(/*blbabla*/);
}

return OrdersByBranches; 

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