扩展方法获取＆QUOT;对于方法＆QUOT没有超载;错误 [英] Extension method Gets "No overload for method" Error

问题描述

我最近刚刚从ASP.Net 3.5升级这个项目到4.0，这样我可以使用，因为线程安全功能的concurrentDictionary，而不是词典。

I just recently upgraded this project from ASP.Net 3.5 to 4.0 so that I could use the concurrentDictionary instead of Dictionary because of the thread safe feature.

要使用它，我用帮助论坛中发现code创建一个扩展。

To use it I created an extension using code found in help forums.

这是所有非常接近的工作，我不知道我怎么可以修改扩展它才能正常工作。

It is all very close to working and I don't know how I can modify the extension for it to work properly.

下面是code：

var catalogs = (from _catalog in entities.catalogs
                        from rolePermission in entities.c_roleperm
                        from _group in entities.c_group
                        from _user in entities.c_user
                        where _group.id == rolePermission.groupID
                            && rolePermission.roleID == user.roleID
                            && _catalog.groupID == rolePermission.groupID
                            && _user.id == _catalog.userID
                        select new { name = _catalog.name, groupID = _catalog.groupID, userName = _user.name, userID = _catalog.userID, groupName = _group.name, ID = _catalog.id }
                );


var listItems = catalogs.ToList(p => new CatalogItem() { name = p.name, groupID = p.groupID, userID = p.userID, username = p.userName, groupName = p.groupName, ID = p.ID }).GroupBy(p => p.groupName).ToConcurrentDictionary(p => p.Key, p => p.ToList());

而code的扩展：

And the code in the extension:

public static class Extentions
{
    public static ConcurrentDictionary<TKey, TValue> ToConcurrentDictionary<TKey, TValue>(
          this IEnumerable<KeyValuePair<TKey, TValue>> source)
    {
        return new ConcurrentDictionary<TKey, TValue>(source);
    }
    public static ConcurrentDictionary<TKey, TValue> ToConcurrentDictionary<TKey, TValue>(
           this IEnumerable<TValue> source, Func<TValue, TKey> keySelector)
    {
        return new ConcurrentDictionary<TKey, TValue>(
            from v in source
            select new KeyValuePair<TKey, TValue>(keySelector(v), v));
    }

这是我收到的错误：

And this is the error that I receive:

错误1无过载方法'ToConcurrentDictionary需要两个参数

我需要修改扩展到在这种情况下工作？任何建议都大大AP preciated。

What would I need to modify for the extension to work in this situation? Any suggestions are greatly appreciated.

推荐答案

您没有过载，它允许你提取项的值：

You don't have an overload which allows you to extract the value from an item:

public static ConcurrentDictionary<TKey, TValue> ToConcurrentDictionary<T, TKey, TValue>(this IEnumerable<T> source, Func<T, TKey> keySelector, Func<T, TValue> valueSelector)
{
    var pairs = source.Select(i => new KeyValuePair<TKey, TValue>(keySelector(i), valueSelector(i)));
    return new ConcurrentDictionary<TKey, TValue>(pairs);
}

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