C# foreach遇到async和await

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一个简单的列子，需要把一个集合的数据添加到数据库中。

我先这样写了，然后报错了

public async Task<IHttpActionResult> Test([FromUri]string name = "")
{
List<string> strList = new List<string>() { "测试", "测试1", "测试2", "测试3", "测试4", "测试5", "测试6", "测试7", "测试8" };
strList.ForEach(async x =>
{
JkSystemname jk = await dbOracle.JkSystemnames.AsQueryable().FirstAsync(ee => ee.Name == x);
if (jk == null)
{
jk = new JkSystemname() { Name = x };
dbOracle.JkSystemnames.Insert(jk);
}
});
return await Task.FromResult(Ok(new { errcode = , errmag = "success" }));
}

两个办法解决循环里面不能使用异步

①把方法提出来，然后返回task，然后一起执行，这样不会按顺序执行

public async Task<IHttpActionResult> Test([FromUri]string name = "")
{
List<string> strList = new List<string>() { "测试", "测试1", "测试2", "测试3", "测试4", "测试5", "测试6", "测试7", "测试8" };
IEnumerable<Task> tasks = strList.Select(x => TestAsync(x));//映射到一个可以遍历的task
await Task.WhenAll(tasks); //使用task.whenall 完成
return await Task.FromResult(Ok(new { errcode = , errmag = "success" }));
} /// <summary>
/// 根据传入的名称，返回需要执行的task代码
/// </summary>
/// <param name="name"></param>
/// <returns></returns>
public async Task TestAsync(string name)
{
JkSystemname jk = await dbOracle.JkSystemnames.AsQueryable().FirstAsync(ee => ee.Name == name);
if (jk == null)
{
jk = new JkSystemname() { Name = name };
dbOracle.JkSystemnames.Insert(jk);
}
}

②扩展方法，一个个的执行

/// <summary>
/// 使用异步遍历处理数据
/// </summary>
/// <typeparam name="T">需要遍历的基类</typeparam>
/// <param name="list">集合</param>
/// <param name="func">Lambda表达式</param>
/// <returns></returns>
public static async Task ForEachAsync<T>(this List<T> list, Func<T, Task> func)
{
foreach (T value in list)
{
await func(value);
}
}

public async Task<IHttpActionResult> Test([FromUri]string name = "")
{
List<string> strList = new List<string>() { "测试", "测试1", "测试2", "测试3", "测试4", "测试5", "测试6", "测试7", "测试8" };
//①先得到集合，然后一起执行
//IEnumerable<Task> tasks = strList.Select(x => TestAsync(x));//映射到一个可以遍历的task
//await Task.WhenAll(tasks); //使用task.whenall 完成
//②一步一步的循环
await strList.ForEachAsync<string>(async x =>
{
JkSystemname jk = await dbOracle.JkSystemnames.AsQueryable().FirstAsync(ee => ee.Name == x);
if (jk == null)
{
jk = new JkSystemname() { Name = x };
dbOracle.JkSystemnames.Insert(jk);
}
}); return await Task.FromResult(Ok(new { errcode = , errmag = "success" }));
}