(Go) Outlook Send HTML Email with Embedded Images and Attachments

This example sends an HTML email with both embedded images and attachments. Other examples exist for:

Sending plain-text email.
Sending HTML email.
Sending HTML email with embedded images.
Sending plain-text email with attachments.

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    // Important: This example requires Chilkat v9.5.0.68 or greater.

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

    http := chilkat.NewHttp()

    // Use your previously obtained access token here:
    // See the following examples for getting an access token:
    //    Get Microsoft Graph OAuth2 Access Token (Azure AD v2.0 Endpoint).
    //    Get Microsoft Graph OAuth2 Access Token (Azure AD Endpoint).
    //    Refresh Access Token (Azure AD v2.0 Endpoint).
    //    Refresh Access Token (Azure AD Endpoint).

    http.SetAuthToken("MICROSOFT_GRAPH_ACCESS_TOKEN")

    // To send mail, we'll POST to the following endpoint:
    // 
    // POST /users/{id | userPrincipalName}/sendMail
    // 
    // (The special keyword "me" may be used in place of a principal name.)
    // 

    // This example will send HTML email containing the following HTML body.
    // After the 

    // 	<html>
    // 	<head>
    // 	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    // 	<meta content="text/html; charset=utf-8">
    // 	</head>
    // 	<body bgcolor="#FFFFFF">
    // 	<font face="Calibri">This is a test <b>HTML email with embedded images</b>.<br>
    // 	<br>
    // 	<img alt="" src="cid:starfish"><br>
    // 	<img alt="" src="cid:hedgehogs"><br>
    // 	</font>
    // 	</body>
    // 	</html>

    // Build the HTML body...
    bCrlf := true
    sbHtmlBody := chilkat.NewStringBuilder()
    sbHtmlBody.AppendLine("<html>",bCrlf)
    sbHtmlBody.AppendLine("<head>",bCrlf)
    sbHtmlBody.AppendLine("<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">",bCrlf)
    sbHtmlBody.AppendLine("<meta content=\"text/html; charset=utf-8\">",bCrlf)
    sbHtmlBody.AppendLine("</head>",bCrlf)
    sbHtmlBody.AppendLine("<body bgcolor=\"#FFFFFF\">",bCrlf)
    sbHtmlBody.AppendLine("<font face=\"Calibri\">This is a test <b>HTML email with embedded images</b>.<br>",bCrlf)
    sbHtmlBody.AppendLine("<br>",bCrlf)
    sbHtmlBody.AppendLine("<img alt=\"\" src=\"cid:starfish\"><br>",bCrlf)
    sbHtmlBody.AppendLine("<img alt=\"\" src=\"cid:hedgehogs\"><br>",bCrlf)
    sbHtmlBody.AppendLine("</font>",bCrlf)
    sbHtmlBody.AppendLine("</body>",bCrlf)
    sbHtmlBody.AppendLine("</html>",bCrlf)

    // Load the embedded image files.
    jpgStarfish := chilkat.NewBinData()
    jpgStarfish.LoadFile("qa_data/jpg/starfish.jpg")
    jpgHedgeHogs := chilkat.NewBinData()
    jpgHedgeHogs.LoadFile("qa_data/jpg/hedgehogs.jpg")

    // Load files that are to be attached (not inline images)
    attach1 := chilkat.NewBinData()
    attach1.LoadFile("qa_data/pdf/fishing.pdf")
    attach2 := chilkat.NewBinData()
    attach2.LoadFile("qa_data/msword/sample.docx")

    // The body of the POST request contains JSON that specifies the email subject, body,
    // recipients, etc.  This example will build the following JSON HTML email with
    // two embedded images and two attachments.
    // 
    // The only difference between an embedded inline image and an attachment is that the
    // inline image must have a cid that corresponds to the "cid:" found in the "src" attribute
    // of an IMG tag within the HTML body of the email.  (The inline image is also marked as "isInline",
    // whereas the attachments are not, but I don't know if this actually makes a difference..)
    // 

    // 	{
    // 	  "message": {
    // 	    "subject": "Sample HTML Email with Embedded Images and Attachments",
    // 	    "body": {
    // 	      "contentType": "html",
    // 	      "content": "The HTML body goes here..."
    // 	    },
    // 	    "toRecipients": [
    // 	      {
    // 	        "emailAddress": {
    // 		  "name": "Chilkat Software",
    // 	          "address": "admin@chilkat.io"
    // 	        }
    // 	      },
    // 	      {
    // 	        "emailAddress": {
    // 	          "address": "chilkat.support@gmail.com"
    // 	        }
    // 	      }
    // 	    ],
    // 	    "ccRecipients": [
    // 	      {
    // 	        "emailAddress": {
    // 		  "name": "Chilkat Blog",
    // 		  "address": "admin@cknotes.com"
    // 	        }
    // 	      }
    // 	    ],
    // 	    "attachments": [
    // 	       {
    // 	         "@odata.type": "#microsoft.graph.fileAttachment",
    // 	         "name": "starfish.jpg",
    // 	         "contentType": "image/jpeg",
    // 	         "size": 6497,
    // 	         "isInline": true,
    // 	         "contentId": "starfish",
    // 	         "contentLocation": null,
    // 	         "contentBytes": "base64_data_here"
    // 	       },
    // 	       {
    // 	         "@odata.type": "#microsoft.graph.fileAttachment",
    // 	         "name": "hedgehogs.jpg",
    // 	         "contentType": "image/jpeg",
    // 	         "size": 48845,
    // 	         "isInline": true,
    // 	         "contentId": "hedgehogs",
    // 	         "contentLocation": null,
    // 	         "contentBytes": "base64_data_here"
    // 	       },
    // 	       {
    // 	         "@odata.type": "#microsoft.graph.fileAttachment",
    // 	         "name": "fishing.pdf",
    // 	         "contentType": "application/pdf",
    // 	         "size": <theActualSize>,
    // 	         "isInline": false,
    // 	         "contentBytes": "base64_data_here"
    // 	       },
    // 	       {
    // 	         "@odata.type": "#microsoft.graph.fileAttachment",
    // 	         "name": "sample.docx",
    // 	         "contentType": "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
    // 	         "size": <theActualSize>,
    // 	         "isInline": false,
    // 	         "contentBytes": "base64_data_here"
    // 	       }
    // 	    ]
    // 	  },
    // 	  "saveToSentItems": true
    // 	}
    // 
    // Build the above JSON.
    json := chilkat.NewJsonObject()
    json.UpdateString("message.subject","Sample HTML Email with Embedded Images and Attachments")
    json.UpdateString("message.body.contentType","html")
    json.UpdateString("message.body.content",*sbHtmlBody.GetAsString())

    json.UpdateString("message.toRecipients[0].emailAddress.name","Chilkat Software")
    json.UpdateString("message.toRecipients[0].emailAddress.address","admin@chilkat.io")
    json.UpdateString("message.toRecipients[1].emailAddress.address","chilkat.support@gmail.com")
    json.UpdateString("message.ccRecipients[0].emailAddress.name","Chilkat Blog")
    json.UpdateString("message.ccRecipients[0].emailAddress.address","admin@cknotes.com")

    json.UpdateString("message.attachments[0].\"@odata.type\"","#microsoft.graph.fileAttachment")
    json.UpdateString("message.attachments[0].name","starfish.jpg")
    json.UpdateString("message.attachments[0].contentType","image/jpeg")
    json.UpdateInt("message.attachments[0].size",jpgStarfish.NumBytes())
    json.UpdateBool("message.attachments[0].isInline",true)
    // This contentId must match the "cid:" in the HTML
    json.UpdateString("message.attachments[0].contentId","starfish")
    json.UpdateNull("message.attachments[0].contentLocation")
    json.UpdateBd("message.attachments[0].contentBytes","base64",jpgStarfish)

    json.UpdateString("message.attachments[1].\"@odata.type\"","#microsoft.graph.fileAttachment")
    json.UpdateString("message.attachments[1].name","hedgehogs.jpg")
    json.UpdateString("message.attachments[1].contentType","image/jpeg")
    json.UpdateInt("message.attachments[1].size",jpgHedgeHogs.NumBytes())
    json.UpdateBool("message.attachments[1].isInline",true)
    // This contentId must match the "cid:" in the HTML
    json.UpdateString("message.attachments[1].contentId","hedgehogs")
    json.UpdateNull("message.attachments[1].contentLocation")
    json.UpdateBd("message.attachments[1].contentBytes","base64",jpgHedgeHogs)

    json.UpdateString("message.attachments[2].\"@odata.type\"","#microsoft.graph.fileAttachment")
    json.UpdateString("message.attachments[2].name","fishing.pdf")
    json.UpdateString("message.attachments[2].contentType","application/pdf")
    json.UpdateInt("message.attachments[2].size",attach1.NumBytes())
    json.UpdateBool("message.attachments[2].isInline",false)
    json.UpdateBd("message.attachments[2].contentBytes","base64",attach1)

    json.UpdateString("message.attachments[3].\"@odata.type\"","#microsoft.graph.fileAttachment")
    json.UpdateString("message.attachments[3].name","sample.docx")
    json.UpdateString("message.attachments[3].contentType","application/vnd.openxmlformats-officedocument.wordprocessingml.document")
    json.UpdateInt("message.attachments[3].size",attach2.NumBytes())
    json.UpdateBool("message.attachments[3].isInline",false)
    json.UpdateBd("message.attachments[3].contentBytes","base64",attach2)

    json.UpdateBool("saveToSentItems",true)

    // -------------------------------------------------------------
    // Important: This example requires Chilkat v9.5.0.68 or greater.
    // -------------------------------------------------------------

    // Send the HTTP POST (i.e. send the HTML email)
    resp := http.PostJson3("https://graph.microsoft.com/v1.0/me/sendMail","application/json",json)
    if http.LastMethodSuccess() != true {
        fmt.Println(http.LastErrorText())
        http.DisposeHttp()
        sbHtmlBody.DisposeStringBuilder()
        jpgStarfish.DisposeBinData()
        jpgHedgeHogs.DisposeBinData()
        attach1.DisposeBinData()
        attach2.DisposeBinData()
        json.DisposeJsonObject()
        return
    }

    // The send succeeded if the response status code = 202.
    // In the success case, there is no response body.  (We just get the response code to know that it succeeded.)
    if resp.StatusCode() != 202 {
        json.Load(resp.BodyStr())
        json.SetEmitCompact(false)
        fmt.Println(*json.Emit())
        fmt.Println("Failed, response status code = ", resp.StatusCode())
    }
    else {
        fmt.Println("Outlook HTML Mail Sent.")
    }

    resp.DisposeHttpResponse()

    http.DisposeHttp()
    sbHtmlBody.DisposeStringBuilder()
    jpgStarfish.DisposeBinData()
    jpgHedgeHogs.DisposeBinData()
    attach1.DisposeBinData()
    attach2.DisposeBinData()
    json.DisposeJsonObject()