CODEWITHSUNDEEP
asp.net-mvcappsettings
Espen
Espen

Reputation: 3727

How do I get AppSettings as a constant value?

Take the code below

Web.config:

<configuration>
  <appSettings>
    <add key="accesstoken:case1" value="00b8d5e4-a318-4f2d-bd5b-e7832861dbb6" />
  </appSettings>
</configuration>

Controller.cs:

public JsonResult GetSomething(string token = "")
{
    switch (token)
    {
        case System.Configuration.ConfigurationManager.AppSettings["accesstoken:case1"]:
           ...
        case ...:
    }
}

So here I get an error for case1 saying a constant value is expected. And I had the impression that AppSettings was constant. But because it's being accessed in the way it is I suppose a constant is impossible.

But I really like switch/cases instead of having a bunch of if/elses, so is it possible to access AppSettings to get a constant value?

Upvotes: 0

Views: 2509

Answers (1)

CodeNotFound
CodeNotFound

Reputation: 23220

Constant inside a file doesn"t mean it is also a constant in the code. Constant in code always have a keyword const. It is not the same. Values configured inside the file settings can be modifiied during execution of your application. Constant fields can't be modified during execution.

A solution to achieve what you need to do without a bunch of if-else or switch-case is at startup of you application to load a dictionary that will contain all key (e.g. starting with accesstoken:*) 

public static Lazy<IDictionary<string, string>> AppSettingsAccessTokens = new Lazy<IDictionary<string, string>>(() =>
{
    return ConfigurationManager.AppSettings.AllKeys.Where(p => p.StartsWith("accesstoken:")).ToDictionary(p => p, p => ConfigurationManager.AppSettings[p]);
});

And finally in your GetSomething method you do like:

public JsonResult GetSomething(string token = "")
{
    var accessTokenSettingKey = AppSettingsAccessTokens.Value.Values.FirstOrDefault(p => p == token)?.Key;

    // ....
}

Upvotes: 2

Related Questions