“字符串'不包含定义'包含' [英] 'string' does not contain a definition for 'Contains'

问题描述

我有像这样的声明：

var vals =
    from StandAloneUserPayment saup in _Session.Query<StandAloneUserPayment>()
        .Fetch(x => x.RecurringPayments)
    where
        saup.User.UserId == userId
        && searchString.Contains(saup.FriendlyName, StringComparer.InvariantCultureIgnoreCase)
    select
        saup;

这似乎正是我应该做的，但我得到了整个符合包含方法，以下信息强调：

This seems to be exactly what I'm supposed to do, but I get the whole line with the Contains method underlined with the following message:

字符串不包含的定义包含和最佳推广方法重载 System.Linq.ParallelEnumerable.Contains< TSource>（ System.Linq.ParallelQuery< TSource>中TSource，System.Collections.Generic.IEqualityComparer< TSource>）有一些无效参数

string does not contain a definition for Contains and the best extension method overload System.Linq.ParallelEnumerable.Contains<TSource>(System.Linq.ParallelQuery<TSource>, TSource, System.Collections.Generic.IEqualityComparer<TSource>) has some invalid arguments

我在做什么错了？

推荐答案

尝试的IndexOf ：

searchString.IndexOf(saup.FriendlyName,
                     StringComparison.InvariantCultureIgnoreCase) != -1

它不工作的原因是因为包含接受扩展方法的的IEqualityComparer< TSource> 是在字符串，它实现了的IEnumerable和下操作;焦炭> ，而不是的IEnumerable<串> ，所以字符串和的IEqualityComparer<字符串方式> 不能被传递给它

The reason it doesn't work is because the Contains extension method that accepts an IEqualityComparer<TSource> is operating on a String, which implements IEnumerable<char>, not IEnumerable<string>, so a string and an IEqualityComparer<string> can't be passed to it.

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