PureBasic

Get the Content-ID of a Related Item

Demonstrates the Chilkat Email.GetRelatedContentID method, which returns the Content-ID of a related item (typically an image or style sheet embedded within an HTML email). The index is zero-based. This example loads an image from a file into a BinData object, adds it as a related item with AddRelatedBd (capturing the generated Content-ID and referencing it from the HTML), then reads that Content-ID back.

Background: The Content-ID is the anchor that ties an inline resource to the HTML that displays it: the body references cid: plus the ID, and the matching related part carries that same Content-ID. Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd. Reading the Content-ID back lets a program verify or rewrite those links — for example when relocating embedded images or converting a message for display outside a mail client.

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IncludeFile "CkBinData.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkEmail.pb"

Procedure ChilkatExample()

    success.i = 0

    ;  Demonstrates the GetRelatedContentID method, which returns the Content-ID of a related
    ;  item.  Related items are typically images and style sheets embedded within HTML emails.
    ;  The index is zero-based.

    email.i = CkEmail::ckCreate()
    If email.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkEmail::setCkSubject(email, "GetRelatedContentID example")

    ;  Load the image data from a file into a BinData object.
    bdImage.i = CkBinData::ckCreate()
    If bdImage.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkBinData::ckLoadFile(bdImage,"qa_data/images/logo.png")
    If success = 0
        Debug CkBinData::ckLastErrorText(bdImage)
        CkEmail::ckDispose(email)
        CkBinData::ckDispose(bdImage)
        ProcedureReturn
    EndIf

    ;  Add the image as a related item from the BinData; capture its generated Content-ID.
    cid.s = CkEmail::ckAddRelatedBd(email,"logo.png",bdImage)
    If CkEmail::ckLastMethodSuccess(email) = 0
        Debug CkEmail::ckLastErrorText(email)
        CkEmail::ckDispose(email)
        CkBinData::ckDispose(bdImage)
        ProcedureReturn
    EndIf

    ;  Reference the related item in the HTML body by its Content-ID.
    sbHtml.i = CkStringBuilder::ckCreate()
    If sbHtml.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbHtml,"<html><body><img src=" + Chr(34) + "cid:PLACEHOLDER_CID" + Chr(34) + "/></body></html>")
    numReplaced.i = CkStringBuilder::ckReplace(sbHtml,"PLACEHOLDER_CID",cid)
    CkEmail::ckSetHtmlBody(email,CkStringBuilder::ckGetAsString(sbHtml))

    ;  Read the Content-ID of the first related item (index 0).
    cid0.s = CkEmail::ckGetRelatedContentID(email,0)
    Debug "Related item 0 Content-ID: " + cid0

    ;  Note: The path "qa_data/images/logo.png" is a relative local filesystem path,
    ;  relative to the current working directory of the running application.


    CkEmail::ckDispose(email)
    CkBinData::ckDispose(bdImage)
    CkStringBuilder::ckDispose(sbHtml)


    ProcedureReturn
EndProcedure