PureBasic

Get a Header Attribute of a Related Item

Demonstrates the Chilkat Email.GetRelatedAttr method, which returns a header-field attribute value from a header field of the Nth related item. The first argument is the zero-based related-item index, the second names a header field, and the third names an attribute within it. 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 the name attribute of the related item's Content-Type header.

Background: Related items (inline images, style sheets) are MIME parts whose headers may carry named parameters — for instance Content-Type: image/png; name="logo.png". Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd, rather than being treated as text. GetRelatedAttr then extracts one named attribute from a chosen header of a specific related part, the related-item analogue of GetAttachmentAttr, so you don't have to parse the raw header yourself.

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

Procedure ChilkatExample()

    success.i = 0

    ;  Demonstrates the GetRelatedAttr method, which returns a header-field attribute value
    ;  from a header field of the Nth related item.  The first argument is the zero-based related-item
    ;  index, the second is the header field name, and the third is the attribute name.

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

    CkEmail::setCkSubject(email, "GetRelatedAttr 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))

    ;  Get the "name" attribute of the related item's Content-Type header (index 0).
    val.s = CkEmail::ckGetRelatedAttr(email,0,"Content-Type","name")
    Debug "Related item Content-Type name attribute: " + val

    ;  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