Question

I’m currently extending some existing code that utilizes a lookup table. As it is now the table is about 25 entries and, for better or worse, the key/values are stored in the appsettings section of the web.conf. They are read into a dictionary and used throughout the application.

I’ll be increasing the size of the lookup table to around 300 entries, which is the complete set of values for this domain – so it’s not likely that it will get much larger nor change frequently. I’m not sure that keeping this data in the web.conf is a good idea. A database is not an option for this implementation, so i’m looking for a alternative way to store this data . Some of my thoughts are:

• A static dictionary?
• Xml file (or some other flat external datafile)
• Leaving it in the appsettings section of web.conf?

I’m leaning toward populating a static dictionary in a class that will contain methods for manipulating the dataset. Any advice, comments or cries of outrage would be appreciated.

Answer 1

You can store your additional key value pairs in a config file referenced via the appSettings element – this keeps your main config file neat, and stores the additional config in it’s own dependent config file.

This is explained in the article MSDN – appSettings Element (General Settings Schema).

This is effectively a combination of your second and third items.

I wouldn’t put it in a static dictionary inside the code for maintenance reasons – a config file is a more obvious place for this data too. By leveraging the built in .Net functionality, you also don’t run the risk of someone else ignoring the Xml file for example.

A more concrete example would be (note file paths are relative to the main application):

app.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>   

   <appSettings file="mykeyvaluepairs.config"/>

</configuration> 

mykeyvaluepairs.config

<?xml version="1.0" encoding="utf-8" ?>
<appSettings>

  <add key="imaginativelynamedkey1" value="imaginativelynamedvalue1" />

</appSettings>

Note that in your original app.config, it is also okay to do the following:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>   

   <appSettings file="mykeyvaluepairs.config">
       <add key="CanBeOverridenByItemInChildConfigFileWithSameName" value="UnicornsGoHere" />
   </appSettings>

</configuration> 

That is, unless you redefine the appsettings in the mykeyvaluepairs.config file, both will exist side by side – but items with the same name in mykeyvaluepairs.config will override values in the main config.