To block some items in dropdown List

Question

I am working on MVC project and have a dropdown to fill with Country Name. But I want to block some country names so that they will not reflect in that dropdown. For blocked countries value of key should be listed in 'web.config' file. I do not want hard code. My current code is mentioned below. It will looks a little mixed up.

Step 1

private static void FillCombos(GuestInformationPresenter model)
{
    FillCountryLists(model);        
}

Step 2 // This code is written in GuestInformation Controller

/// <summary>
/// Function to fill countries in combos.
/// </summary>
/// <param name="model">GuestInformationPresenter type of object</param>
private static void FillCountryLists(GuestInformationPresenter model)
{
    //I want to add some Linq code here to Block some countries. 
    model.FillCountryLists(ReservationService.RetrieveCountries());
}

Step 3 // This code is written in GuestInformation Presenter

public void FillCountryLists(Dictionary<string, string> countryList)
{
    this.CountryList = countryList;
}    

Step 4 // Function to retrieve collection of Countries. /// /// collection of countries public static KeyValuePair[] RetrieveCountries() { return LookupManager.RetrieveCountries(); }

public static Dictionary<string, string> RetrieveCountries()
{
    KeyValuePair<string, string>[] countries = 
        CruiseLookup.RetrieveCountries();
    return countries.ToDictionary<KeyValuePair<string, string>, string, string>(pair => pair.Key, pair => pair.Value);
}

Step 5 // This code is written in LookManager.cs

public static KeyValuePair<string, string>[] RetrieveCountries()
{
    var countries = from LookupData.CountryRow countryRow in LookupManagerCache.Retrieve().CountryRows
    orderby countryRow.Name
    select new KeyValuePair<string, string>(
        DataField.RetrieveValue(() => countryRow.Code),
        DataField.RetrieveValue(() => countryRow.Name));

    return countries.ToArray();
}

The method that does return countries.ToArray(); (Step 5) is common to retrieve country list but when I want this list to bind GuestInformation Controller then I want to block those countries.

Currently from step 4 I am getting key-value pair of different countries. For example if country is Guiena then Key-value pair from step 4 will be key='GU' value='GUIENA'

After that in step 3 I am using this code to remove 'Guiena' country

public void FillCountryLists(Dictionary<string, string> countryList)
{   
    countryList.remove(key="GU");
    countryList.remove(key="XYZ");  // Here XYZ is key of any other country
    this.CountryList = countryList;
}

But I want to add some LINQ or other code in step 2 (at controller level) to remove countries.

The main thing that I want is that for blocked countries value of key should be listed in 'web.config' file . Can you please assist me to fix it?

Answer 1

You can use Contains like this:

var excludeKeys = new string[] { "GU", "XYZ" };
var countries = from ....
                where !excludeKeys.Contains(your key field)
                orderby ....
                select ....;

So in order your codes, you need to pass excludeKeys to your RetrieveCounties method and use them in query.

Step 2

private static void FillCountryLists(GuestInformationPresenter model)
{
    var excludeKeys = new string[] { "GU", "XYZ" }; 
    model.FillCountryLists(ReservationService.RetrieveCountries(excludeKeys));
}

Step 5

public static KeyValuePair<string, string>[] RetrieveCountries(List<string> excludeKeys)
{
    var countries = from ....
                    where !excludeKeys.Contains(your key field)
                    orderby ....
                    select ....;
    return ....
}

It's enough to add an empty list to RetrieveCountries method to don't filter countries.

As mentioned in comments and in Ehsan Sajjad's answer, you can store these values as a comma separated string in web.config or a setting.setting file then retrieve it, split it, put in list and then pass to your method.

Answer 2

In your web.config add the list of blocked countries, or if you don't have that section add it under configuration section:

<configuration>
  <appSettings>
    <add key="BlockedCountries" value="GU,XYZ"/>
  </appSettings>
</configuration>

and then in your controller:

 using System.Web.Configuration;
 ..............
 ..............




var blockedCountries =  WebConfigurationManager.AppSettings["BlockedCountries"].Split(',',StringSplitOptions.RemoveEmptyEntries);

var result =  model.countries.Where(x=> !blockedCountries.Contains(x.Key)).ToArray();