如何将System.Web.Configuration.WebConfigurationManager.AppSettings从String转换为INT

I have defined the following inside my web.config file:-

我在web.config文件中定义了以下内容： -

<add key="TechPageSize" value="20" />

But I m unable to reference this value inside my paging parameters as follow:-

但我无法在我的分页参数中引用此值，如下所示： -

var servers = repository.AllFindServers(withOutSpace).OrderBy(a => a.Technology.Tag).ToPagedList(page, (Int32)System.Web.Configuration.WebConfigurationManager.AppSettings["TechPageSize"]);

and I will get an error that it can not change String to INT.

我将得到一个错误，它不能将String更改为INT。

Any idea what is the problem ?

不知道是什么问题？

3 个解决方案

#1

int techPageSize;
if (!int.TryParse(ConfigurationManager.AppSettings["TechPageSize"], out techPageSize))
{
    throw new InvalidOperationException("Invalid TechPageSize in web.config");
}

Int32.TryParse has two effects:

Int32.TryParse有两个效果：

It converts the app setting to an integer and stores the result in techPageSize, if possible.
如果可能，它会将应用程序设置转换为整数并将结果存储在techPageSize中。
If the value cannot be converted, the method returns False, allowing you to handle the error as you see fit.
如果无法转换该值，则该方法返回False，允许您根据需要处理错误。

PS: It suffices to use ConfigurationManager.AppSettings, once you have imported the System.Configuration namespace.

PS：导入System.Configuration命名空间后，只需使用ConfigurationManager.AppSettings即可。

#2

The result of

的结果

System.Web.Configuration.WebConfigurationManager.AppSettings["TechPageSize"]

is a string, you can't just cast a string to int. Use Convert.ToInt32 or int.TryParse to get the integer value of the string.

是一个字符串，你不能只是将一个字符串强制转换为int。使用Convert.ToInt32或int.TryParse获取字符串的整数值。

int pagesize = Convert.ToInt32(System.Web.Configuration.WebConfigurationManager.AppSettings["TechPageSize"]);

要么

bool succeed = int.TryParse(System.Web.Configuration.WebConfigurationManager.AppSettings["TechPageSize"], out pagesize);

#3

Try:

尝试：

Convert.ToInt32(System.Web.Configuration.WebConfigurationManager.AppSettings["TechPageSize"])

This will error if the convert fails. You could use int.Tryparse in case it doesn't convert to an int, but the fact is this is a config setting and only you have control over this value - it's not user-submitted so catering for error would be overkill IMO.

如果转换失败，这将出错。你可以使用int.Tryparse，如果它没有转换为int，但事实是这是一个配置设置，只有你可以控制这个值 - 它不是用户提交的，所以迎合错误将是矫枉过正的IMO。

#1

int techPageSize;
if (!int.TryParse(ConfigurationManager.AppSettings["TechPageSize"], out techPageSize))
{
    throw new InvalidOperationException("Invalid TechPageSize in web.config");
}