Using Replace Patterns in Email

Demonstrates how to use the replace patterns (mail-merge) feature in Chilkat MailMan.
Chilkat C# Downloads

bool success = false;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// ---------------------------------------------------------------------
// Create an email template for sending.
Chilkat.Email emailTemplate = new Chilkat.Email();

// We're going to replace "FIRST_NAME" with an actual name.
// We arbitrarily chose "FIRST_NAME".  We can choose anything, such as "CUSTOMER_NAME" or "THE_RECIPIENT_NAME"...
emailTemplate.Subject = "Hello FIRST_NAME,";

emailTemplate.From = "john@example.com";
emailTemplate.AddTo("FIRST_NAME","RECIPIENT_EMAIL");

emailTemplate.SetHtmlBody("<html><body><h2>Hello FIRST_NAME,</h2><p>Your order for PRODUCT_NAME has been shipped.</p></body></html>");

// If the email is saved to a file, we can see what it contains:
emailTemplate.SaveEml("qa_output/emailTemplate.eml");

// For example:

// MIME-Version: 1.0
// Date: Tue, 26 Apr 2022 07:10:52 -0500
// Message-ID: <715CF231A9F07B0B9FDB073518CD94138D791866@XYZ>
// Content-Type: text/html; charset=us-ascii
// Content-Transfer-Encoding: 7bit
// X-Priority: 3 (Normal)
// Subject: Hello FIRST_NAME,
// From: john@example.com
// To: FIRST_NAME <RECIPIENT_EMAIL>
// 
// <html><body><h2>Hello FIRST_NAME,</h2><p>Your order for PRODUCT_NAME has been shipped.</p></body></html>

// ---------------------------------------------------------------------
// Demonstrate replace patterns by setting and then rendering to MIME.

Chilkat.MailMan mailman = new Chilkat.MailMan();

emailTemplate.SetReplacePattern("FIRST_NAME","Elon");
emailTemplate.SetReplacePattern("RECIPIENT_EMAIL","elon.musk@example.com");
emailTemplate.SetReplacePattern("PRODUCT_NAME","Twitter Corporation");

// Render to MIME to see what we get.
// Note: When the MailMan sends an email, it renders the email to MIME and then sends.
// The rendering process is to do replacements, or possibly sign, encrypt, etc.
// When MailMan.SendEmail is called, internally the email is rendered, and the rendered email is sent.
// The equivalent to MailMan.Send email is to call email.RenderToMime followed by MailMan.SendMime.
string mime = mailman.RenderToMime(emailTemplate);
Debug.WriteLine(mime);

// This is the rendered MIME:

// MIME-Version: 1.0
// Date: Tue, 26 Apr 2022 07:25:49 -0500
// Message-ID: <750582BCDC891C67B48CEE2293C08B902C3891E9@XYZ>
// Content-Type: text/html; charset=us-ascii
// Content-Transfer-Encoding: 7bit
// X-Priority: 3 (Normal)
// Subject: Hello Elon,
// From: john@example.com
// To: Elon <elon.musk@example.com>
// 
// <html><body><h2>Hello Elon,</h2><p>Your order for Twitter Corporation has been shipped.</p></body></html>

// Note: When rendering, the Date and Message-ID headers are automatically regenerated.

// ---------------------------------------------------------------------
// An application can see what replacement patterns it previously set by calling SetReplacePattern multiple times.
int count = emailTemplate.NumReplacePatterns;
Debug.WriteLine("Number of replace patterns: " + Convert.ToString(count));

int i = 0;
while (i < count) {
    // Note: The GetReplaceString method was found to not be working correctly.  It was returning the same value as GetReplacePattern.
    // It is fixed in Chilkat v9.5.0.91
    Debug.WriteLine(emailTemplate.GetReplacePattern(i) + ": " + emailTemplate.GetReplaceString(i));
    i = i + 1;
}

// Or lookup a replacement pattern by name:
string name = "FIRST_NAME";
Debug.WriteLine(name + " = " + emailTemplate.GetReplaceString2(name));

// Sample output:

// Number of replace patterns: 3
// FIRST_NAME: Elon
// RECIPIENT_EMAIL: elon.musk@example.com
// PRODUCT_NAME: Twitter Corporation
// FIRST_NAME = Elon

// ---------------------------------------------------------------------
// Finally... demonstrate sending emails using the replacement patterns.
// 

// Set our mail server settings..
mailman.SmtpHost = "smtp.mail.us-west-2.awsapps.com";
mailman.SmtpSsl = true;
mailman.SmtpPort = 465;

mailman.SmtpUsername = "john@example.com";
mailman.SmtpPassword = "the_password";

// Imagine we have data in JSON format, and we wish to send the templated email to each recipient...
// 

// {
// 	"mail_merge" : [
// 		{
// 			"to": "mary@example.com",
// 			"name": "Mary",
// 			"product": "Widget 1" 
// 		},
// 		{
// 			"to": "robert@example.com",
// 			"name": "Robert",
// 			"product": "Widget 2"
// 		}	
// 		...
// 	]
// }

Chilkat.JsonObject json = new Chilkat.JsonObject();
success = json.LoadFile("qa_data/json/mail_merge.json");
if (success == false) {
    Debug.WriteLine(json.LastErrorText);
    return;
}

string emailAddr;
string firstName;
string product;

i = 0;
count = json.SizeOfArray("mail_merge");
while (i < count) {
    json.I = i;
    emailAddr = json.StringOf("mail_merge[i].to");
    firstName = json.StringOf("mail_merge[i].name");
    product = json.StringOf("mail_merge[i].product");

    emailTemplate.SetReplacePattern("FIRST_NAME",firstName);
    emailTemplate.SetReplacePattern("RECIPIENT_EMAIL",emailAddr);
    emailTemplate.SetReplacePattern("PRODUCT_NAME",product);

    success = mailman.SendEmail(emailTemplate);
    if (success == false) {
        Debug.WriteLine(mailman.LastErrorText);
        return;
    }

    Debug.WriteLine("Send email to " + emailAddr);

    i = i + 1;
}

Debug.WriteLine("Success.");