How do I convert switch case into a lookup table with keys, values, etc.

Question

I'm not sure how to convert this switch case to a lookup table. How do I do that?

getContactTypeTitle(contactTypeCode: string): string {

    let contactType = 'Site Contact';

    switch (contactTypeCode) {

      case 'SiteApp_CACFP_PrincipleDirector':

        contactType = 'Principle Director';

        break;

      case 'SiteApp_CACFP_PrincipleAsstDir':

        contactType = 'Principle Assistant Director';

        break;

      case 'SiteApp_CACFP_Cook':

        contactType = 'Cook';

        break;

    }

    return contactType;

  }

 

Answer 1

We assume a database here?

Ok, then first we assume the lookup table - say like this:

so, nice about above is we can add lots more, not have to change code.

c# code for above then becomes:

    string GetContactType(string sName)  
    {  
        string Result = "Site Contact";  
        if (sName == "")  
            return Result;  
  
        using (SqlConnection conn = new SqlConnection(Properties.Settings.Default.TEST4))  
        {  
            string strSQL   
                = "SELECT Description from ContactTypes where ContactType = @ConType";  
            using(SqlCommand cmdSQL = new SqlCommand(strSQL,conn))  
            {  
                cmdSQL.Parameters.Add("@ConType", SqlDbType.NVarChar).Value = sName;  
                conn.Open();  
                object s = cmdSQL.ExecuteScalar();  
                if (s != null)  
                    Result = s.ToString();  
            }  
        }  
        return Result;  
    }  

So now you can go say:

TextBox2.Text = GetContactType("SiteApp_CACFP_Cook");

And the result should be cook.

Regards,
Albert D. Kallal (Access MVP 2003-2017)
Edmonton, Alberta Canada

Answer 2

Hi @bootsy1974 ,
A Map lookup would be pretty simple to implement.

const contactTypeByCode = new Map([  
    ['SiteApp_CACFP_PrincipleDirector', 'Principle Director'],  
    ['SiteApp_CACFP_PrincipleAsstDir', 'Principle Assistant Director'],  
    ['SiteApp_CACFP_Cook', 'Cook'],  
]);  
const getContactTypeTitle = (contactTypeCode: string) {  
    return contactTypeByCode.get(contactTypeCode) || 'Site Contact';  
};  

You might wish to increase the type-safety by requiring the caller to pass a code that's in the Map already.

const contactTypeByCodeArr = [  
    ['SiteApp_CACFP_PrincipleDirector', 'Principle Director'],  
    ['SiteApp_CACFP_PrincipleAsstDir', 'Principle Assistant Director'],  
    ['SiteApp_CACFP_Cook', 'Cook'],  
] as const;  
type ContactCode = typeof contactTypeByCodeArr[number][0];  
const contactTypeByCode = new Map(contactTypeByCodeArr);  
const getContactTypeTitle = (contactTypeCode: ContactCode) {  
    return contactTypeByCode.get(contactTypeCode);  
};  

Best regards,
Yijing Sun

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