(SQL Server) Manually Follow HTTP Redirects

Demonstrates how to manually follow redirects for an HTTP GET.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    -- This example requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @http int
    -- Use "Chilkat_9_5_0.Http" for versions of Chilkat < 10.0.0
    EXEC @hr = sp_OACreate 'Chilkat.Http', @http OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- The FollowRedirects property controls whether redirects
    -- are automatically followed.  The default behavior is to
    -- automatically follow redirects.

    -- Explicitly set FollowRedirects so that redirects are NOT automatically taken:
    EXEC sp_OASetProperty @http, 'FollowRedirects', 0

    DECLARE @resp int
    EXEC sp_OAMethod @http, 'QuickGetObj', @resp OUT, 'http://yandex.ru/'
    EXEC sp_OAGetProperty @http, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @http, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @http
        RETURN
      END

    DECLARE @status int
    EXEC sp_OAGetProperty @resp, 'StatusCode', @status OUT

    PRINT 'HTTP Response Status: ' + @status

    -- The FinalRedirectUrl property will contain the redirect URL
    -- If FollowRedirects was equal to 1, then all of the 
    -- intermediate redirects (if any) would be followed until
    -- there were no more redirects.  However, because 
    -- FollowRedirects is not 1, FinalRedirectUrl contains
    -- the next redirect URL.

    DECLARE @loopCount int
    SELECT @loopCount = 0

    WHILE (@status = 302)
      BEGIN

        -- IMPORTANT: This example requires Chilkat v9.5.0.49 or greater because
        -- the FinalRedirectUrl in prior versions is only set when redirects
        -- are automatically followed.   Starting in v9.5.0.49, the FinalRedirectUrl is
        -- set to the next redirect URL when a 301/302 response is received, regardless
        -- of the value of the FollowRedirects property.

        EXEC sp_OAGetProperty @http, 'FinalRedirectUrl', @sTmp0 OUT
        PRINT 'Redirect URL: ' + @sTmp0

        EXEC @hr = sp_OADestroy @resp

        DECLARE @nextUrl nvarchar(4000)
        EXEC sp_OAGetProperty @http, 'FinalRedirectUrl', @nextUrl OUT
        EXEC sp_OAMethod @http, 'QuickGetObj', @resp OUT, @nextUrl
        EXEC sp_OAGetProperty @http, 'LastMethodSuccess', @iTmp0 OUT
        IF @iTmp0 = 0
          BEGIN
            EXEC sp_OAGetProperty @http, 'LastErrorText', @sTmp0 OUT
            PRINT @sTmp0
            EXEC @hr = sp_OADestroy @http
            RETURN
          END

        EXEC sp_OAGetProperty @resp, 'StatusCode', @status OUT

        PRINT 'HTTP Response Status: ' + @status

        -- For safety, prevent infinite loops by
        -- keeping a loopCount and only allows following a max 
        -- of 10 redirects:
        SELECT @loopCount = @loopCount + 1
        IF @loopCount > 10
          BEGIN
            EXEC @hr = sp_OADestroy @resp


            PRINT 'Too many redirects.'
            EXEC @hr = sp_OADestroy @http
            RETURN
          END

        EXEC @hr = sp_OADestroy @resp

      END

    EXEC @hr = sp_OADestroy @http


END
GO