Visual FoxPro

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 lnSuccess
LOCAL loMime
LOCAL lcSubject

lnSuccess = 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).

loMime = CreateObject('Chilkat.Mime')

lnSuccess = loMime.SetBodyFromPlainText("Hello.")
IF (lnSuccess = 0) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    CANCEL
ENDIF

*  Unlike AddHeaderField, SetHeaderField ensures exactly one field with this name.
lnSuccess = loMime.SetHeaderField("Subject","Weekly Report")
IF (lnSuccess = 0) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    CANCEL
ENDIF

*  Setting it again replaces the previous value rather than adding a duplicate.
lnSuccess = loMime.SetHeaderField("Subject","Weekly Report (revised)")
IF (lnSuccess = 0) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    CANCEL
ENDIF

lcSubject = loMime.GetHeaderField("Subject")
IF (loMime.LastMethodSuccess = 0) THEN
    ? loMime.LastErrorText
    RELEASE loMime
    CANCEL
ENDIF

? "Subject: " + lcSubject

RELEASE loMime