如何合并两个LINQ表达式？

Question

I have the following LINQ query in c#

var stats = from s in context.Stats                                                                                                  
        select s;

Expression<Func<Stat, bool>> e1 = s => s.Age >= 15 && s.Age < 25;
Expression<Func<Stat, bool>> e2 = s => s.Age >= 40 && s.Age < 50;

stats = stats.Where(e1);

This code works and gives me the rows from the Stats table where Age is between 15 an 25.

Now, i would like to get the rows from 15 to 25 AND from 40 to 50.

How do I combine those 2 expressions ?

thanks

Answer 1

How about...

Expression<Func<Stat, bool>> e1 = s => 
   (s.Age >= 15 && s.Age < 25) || (s.Age >= 40 && s.Age < 50);

Answer 2

It's a bit ugly but if you want to keep them as expressions:

stats = stats.Where(s => (e1.Compile()(s) || e2.Compile()(s))).ToList();

If you can change them to Func s it's cleaner:

Func<Stat, bool> e1 = s => s.Age >= 15 && s.Age < 25;
Func<Stat, bool> e2 = s => s.Age >= 40 && s.Age < 50;

stats = stats.Where(s => e1(s) || e2(s)).ToList();

Answer 3

你可以这样做一个联盟

stats = stats.Where(e1).Union(stats.Where(e2));

Answer 4

Expression<Func<Stat, bool>> GetOrExpression(
    Expression<Func<Stat, bool>> e1,
    Expression<Func<Stat, bool>> e2)
{
    return s => e1.Compile()(s) || e2.Compile()(s);
}

Expression<Func<Stat, bool>> e1 = s => s.Age >= 15 && s.Age < 25;
Expression<Func<Stat, bool>> e2 = s => s.Age >= 40 && s.Age < 50;

stats = stats.Where(GetOrExpression(e1, e2));