ConfigurationManager.AppSettings in returning null

Question

I am using ConfigurationManager.AppSettings[myKey] to read a value from the app.config file in my windows application, but the value returned is always null, even though the key exists and it has a value, Deas any one know why?

Thanks

Only your code can tell the tale, post it (are you retrieving in the same case) — V4Vendetta, Jul 07 '11 at 06:25

score 25 · Accepted Answer · answered Jul 07 '11 at 06:37

25

One, perhaps easier, alternative is to use a Settings file. This encapsulates the creation and maintenance of App.config values in a designer GUI and generates code for accessing the values.

To add a Settings file, right click your project in VS and click 'Add -> New Item', select 'Settings file' and give it a meaningful name, e.g. MainSettings.settings. You can then add an item, e.g. Foo, specify whether it is application or user-wide, define it's type and a assign it a value. In your code you can retreive the value by simple writing MainSettings.Default.Foo.

After compilation, you can change the value by editing the config file. The setting will appear as follows:-

<applicationSettings>
    <YourNamespace.MainSettings>
        <setting name="Foo" serializeAs="String">
            <value>Bar</value>
        </setting>
    </YourNamespace.MainSettings>
</applicationSettings>

answered Jul 07 '11 at 06:37

Adam Ralph

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Awesome suggestion, @Adam. Bumped you over 8000 rep for that. Nice work! – retrodrone Aug 04 '11 at 03:28
@retrodone - thanks! I've just logged in for the first time after getting back from holiday... – Adam Ralph Aug 28 '11 at 19:49
When you alter the config manually, it doesn't automatically propagate to the settings in VS. You have to go to properties and let it resolve them. – Ε Г И І И О Jun 05 '13 at 06:19
Let me contribute! Dif between Application and User scope: [link](http://stackoverflow.com/a/13047003/5750078) – Alvaro Rodriguez Scelza Sep 18 '16 at 23:09

score 9 · Answer 2 · edited Jul 06 '17 at 17:30

9

Hard to say from what you've provided here:

Check your spelling of the value in myKey
Ensure you are looking at the right app.config - if this call is in a referenced library and you're expecting a value to come from the calling project's app.config, but your library has an app.config for some reason it may be causing your problem.

edited Jul 06 '17 at 17:30

Chris

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answered Jul 07 '11 at 06:26

Stuart Helwig

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I actuallay have only one app.config file, and I am just calling ConfigurationManager.AppSettings[myKey], and the key exists! not sure whay this is happening – Hassan Mokdad Jul 07 '11 at 06:30
1

ConfigurationManager.AppSettings[myKey] is [case-insensitive](https://stackoverflow.com/questions/3295293/how-to-check-if-an-appsettings-key-exists#comment49367267_6071115); just edited this answer. – Chris Jul 06 '17 at 17:30

score 0 · Answer 3 · answered Apr 01 '13 at 19:08

i have two project in my solution first i add app.config file in class library project which all instances is call from console application i added these entries in config file in class lib project

<appSettings> 
<add key="userName" value="user2" /> 
<add key="emilsLimit" value="50" /> 
</appSettings>

it was throwing null exception when i get these in a class in class library project but when i delete app.config from class Library project and added in Console project it works.Cheers

Note: Class lib project reference is added in console

score -1 · Answer 4 · answered Jan 17 '14 at 14:27

-1

I was having the same problem, but when I added an empty string ( + "") on the end it picks up the string in the appsettings

for example

string s = ConfigurationManager.AppSettings["myKey"] + "";

answered Jan 17 '14 at 14:27

beaumondo

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It wouldn't since the value is a null it would have an empty string – kirushan Feb 01 '19 at 05:46

ConfigurationManager.AppSettings in returning null

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