Xbase++

Set a MIME Header Field

Demonstrates the Chilkat Mime.SetHeaderField method, which sets a single header field. The first argument is the field name and the second is the value. All existing occurrences are removed and one replacement is inserted, or a new field is added if none exists.

Background: For headers that should appear exactly once — Subject, From, Content-Type — this is the method to use, because it guarantees a single occurrence no matter how many times you call it. That idempotence is the key difference from AddHeaderField, which would leave duplicates behind. Setting an empty value removes the field.

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LOCAL nSuccess
LOCAL oMime
LOCAL cSubject

nSuccess := 0

//  Demonstrates the Mime.SetHeaderField method, which sets a single header field.  The 1st argument
//  is the field name and the 2nd is the value.  All existing occurrences are removed and one
//  replacement is inserted (or a new field is added if none exists).

oMime := CreateObject("Chilkat.Mime")

nSuccess := oMime:SetBodyFromPlainText("Hello.")
IF (nSuccess == 0)
    ? oMime:LastErrorText
    oMime:destroy()
    RETURN
ENDIF

//  Unlike AddHeaderField, SetHeaderField ensures exactly one field with this name.
nSuccess := oMime:SetHeaderField("Subject", "Weekly Report")
IF (nSuccess == 0)
    ? oMime:LastErrorText
    oMime:destroy()
    RETURN
ENDIF

//  Setting it again replaces the previous value rather than adding a duplicate.
nSuccess := oMime:SetHeaderField("Subject", "Weekly Report (revised)")
IF (nSuccess == 0)
    ? oMime:LastErrorText
    oMime:destroy()
    RETURN
ENDIF

cSubject := oMime:GetHeaderField("Subject")
IF (oMime:LastMethodSuccess == 0)
    ? oMime:LastErrorText
    oMime:destroy()
    RETURN
ENDIF

? "Subject: " + cSubject

oMime:destroy()