[英]Using LINQ to get a list of items where the item contains a part of an item from another list
有一個模型列表:
List<string> models = new List<string>
{
"abcd1234",
"xycd9999",
"zzz999z",
"ros7777"
};
有過濾器清單:
List<string> filterer = new List<string>
{
"cd",
"9999"
};
我正在嘗試使用LINQ來獲取包含過濾器項目的所有模型作為其名稱的一部分。
對於這個例子:
因此,LINQ操作將返回兩個項目的列表:“abcd1234”和“xycd9999”。
var filteredList = models
.Where(m => m.Contains("/*HERE WILL BE THE FILTERER ITEMS*/"))
.Distinct()
.ToList();
什么是正確的語法?
var filteredList = models
.Where(x => filterer.Any(y => x.Contains(y))
.ToList();
Distinct
在這里沒有用處,因為Where
調用不會引入重復項(除非models
具有重復值,並且您希望刪除這些重復項)。
嘗試使用PredicateBuilder作為鏈接:
public static class PredicateBuilder
{
public static Expression<Func<T, bool>> True<T> () { return f => true; }
public static Expression<Func<T, bool>> False<T> () { return f => false; }
public static Expression<Func<T, bool>> Or<T> (this Expression<Func<T, bool>> expr1,
Expression<Func<T, bool>> expr2)
{
var invokedExpr = Expression.Invoke (expr2, expr1.Parameters.Cast<Expression> ());
return Expression.Lambda<Func<T, bool>>
(Expression.OrElse (expr1.Body, invokedExpr), expr1.Parameters);
}
public static Expression<Func<T, bool>> And<T> (this Expression<Func<T, bool>> expr1,
Expression<Func<T, bool>> expr2)
{
var invokedExpr = Expression.Invoke (expr2, expr1.Parameters.Cast<Expression> ());
return Expression.Lambda<Func<T, bool>>
(Expression.AndAlso (expr1.Body, invokedExpr), expr1.Parameters);
}
}
在你的情況下:
List<string> models = new List<string>
{
"abcd1234",
"xycd9999",
"zzz999z",
"ros7777"
};
List<string> filterer = new List<string>
{
"cd",
"9999"
};
var predicate = PredicateBuilder.False<string>();
foreach (string filter in filterer)
{
predicate = predicate.Or(f => f.Contains(filter));
}
var filteredList = models.AsQueryable().Where(predicate).ToList();
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