C#: How to make sure a settings variable exists before attempting to use it from another assembly?

Question

I have the following:

using CommonSettings = MyProject.Commons.Settings;

public class Foo
{
    public static void DoSomething(string str)
    {
        //How do I make sure that the setting exists first?
        object setting = CommonSettings.Default[str];

        DoSomethingElse(setting);
    }
}

https://msdn.microsoft.com/en-us/library/system.configuration.configurationmanager.appsettings.aspx — CAD bloke, Apr 25 '16 at 05:21

score 30 · Answer 1 · answered Jan 09 '14 at 13:02

30

If you are using a SettingsPropertyCollection you have to loop and check which settings exists yourself it seems, since it doesn't have any Contains-method.

private bool DoesSettingExist(string settingName)
{
   return Properties.Settings.Default.Properties.Cast<SettingsProperty>().Any(prop => prop.Name == settingName);
}

answered Jan 09 '14 at 13:02

salle55

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2

thx salle55. great work. For those that don't have using System.Configuration please add prefix System.Configuration. to SettingsProperty> – gg89 Jan 12 '17 at 06:42

Justin Niessner · Accepted Answer · 2011-01-10T14:34:30.577

6

Depending on what type CommomSettings.Default is, a simple null check should be fine:

if(setting != null)
    DoSomethingElse(setting);

If you want to check BEFORE trying to retrieve the setting, you need to post the Type of CommonSettings.Default. It looks like a Dictionary so you might be able to get away with:

if(CommonSettings.Default.ContainsKey(str))
{
    DoSomethingElse(CommonSettings.Default[str]);
}

edited Jan 10 '11 at 14:34

answered Jan 10 '11 at 14:29

Justin Niessner

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I thought he was more asking how to _ensure_ that the setting is present, not just to check whether it is present. – Uwe Keim Jan 10 '11 at 14:31
1

@Uwe - You might be right. I couldn't tell from the wording in the OP's question. I added something for that case as well. – Justin Niessner Jan 10 '11 at 14:35
1

It is however a Settings.settings file is constructed... I don't think it's a Dictionary type since `CommonSettings.Default.ContainsKey(...)` is not in the intellisense. – michael Jan 10 '11 at 16:24
2

This doesn't work with Properties.Settings.Default. @Salle55 provided a good solution that does work with Properties.Settings.Default below. – Farrah Stark Jun 12 '14 at 18:11
For me: `CommonSettings.Default.Context.ContainsKey(str)` (VS 2019, .NET4.5) – David Silva-Barrera Aug 12 '21 at 10:28

score 6 · Answer 3 · edited Dec 03 '11 at 20:01

6

try
{
    var x = Settings.Default[bonusMalusTypeKey]);
}
catch (SettingsPropertyNotFoundException ex)
{
    // Ignore this exception (return default value that was set)
}

edited Dec 03 '11 at 20:01

animuson

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answered Dec 03 '11 at 19:33

ajoka

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Some description would be useful! – Parris Nov 05 '12 at 08:26

score 5 · Answer 4 · edited Jul 06 '11 at 21:01

5

This is how you deal with it:

if(CommonSettings.Default.Properties[str] != null)
{
    //Hooray, we found it!
}
else
{
    //This is a 'no go'
}

edited Jul 06 '11 at 21:01

DarthJDG

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answered Jul 06 '11 at 20:23

André Filipe

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1

this condition will be true even you haven't set it before. I think OP wanted to know this settings have set before. – Javidan May 24 '18 at 20:11

score 0 · Answer 5 · answered Jan 10 '11 at 14:39

You could do the following:

public static void DoSomething(string str)
{
    object setting = null;

    Try
    {
        setting = CommonSettings.Default[str];
    }
    catch(Exception ex)
    {
        Console.out.write(ex.Message);
    }

    if(setting != null)
    {
        DoSomethingElse(setting);
    }
}

This would ensure the setting exists - you could go a bit further and try and catch the exact excetion - e.g catch(IndexOutOfBoundsException ex)

Just seen your update Justin - Your solution looks allot cleaner :) — GaryT, Jan 10 '11 at 14:40

C#: How to make sure a settings variable exists before attempting to use it from another assembly?

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