Question

I have a string with a message containing some fields I want to swap out to actual values

var message = "Hi [CustomerName]. Its [TODAY], nice to see you were born on the [DOB]!";
var mappingCodes = new List<string> {"[CUSTOMER_NAME]","[DOB]",[TODAY]};
var customEmails = new Dictionary<string, string>();
var today = DateTime.Now;
var customers = new List<Customer>()
{
    new Customer()
        {
            FirstName = "Jo",
            LastName = "Bloggs",
            Email = "[e-mail]",
            DOB = "10/12/1960"
        }
};
foreach (var customer in customers)
{
    var emailMessage = "";
    customEmails.Add(customer.Email,emailMessage);
}

What I’m trying to do is loop through each of the customers and take the message replacing any of the mappingCodes with actual codes.

e.g. [Today] Would be the today and CustomerName would be Customer.FirstName + Customer.LastName

There could be 1000’s of customers so I need something robust. I’m just not sure how to first check the string contains any of the mappingCodes and then replace them with the desired values.

Any advice?

Answer 1

You can use Regex.Replace(string, MatchEvaluator):

var customers = new[] {
    new {
        Name = "Fred Flintstone",
        City = "Bedrock"
    },
    new {
        Name = "George Jetson",
        City = "Orbit City"
    }
};

string template = "Hello, [NAME] from [CITY]!";
var re = new Regex(@"\[\w+\]"); // look for all "words" in square brackets

foreach (var customer in customers)
{
    Trace.WriteLine(
        re.Replace(template, m => {
            // determine the replacement string
            switch (m.Value) // m.Value is the substring that matches the RE.
            {
                // Handle getting and formatting the properties here
                case "[NAME]":
                    return customer.Name;
                case "[CITY]":
                    return customer.City;
                default:
                    // The "mapping code" is not supported, I just return the 
                    // original substring
                    return m.Value;
            }
        }));
}

Obviously the above is just the general approach, you’ll have to modify it to support your mapping codes and data structures.