SQL Server

Read S3 Object Metadata of File Already Uploaded to S3

See more Amazon S3 Examples

Demonstrates how to retrieve the metadata from an S3 object.

The HEAD operation retrieves metadata from an object without returning the object itself. This operation is useful if you are interested only in an object's metadata. To use HEAD, you must have READ access to the object.

A HEAD request has the same options as a GET operation on an object. The response is identical to the GET response except that there is no response body.

SQL Server

-- 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)
    DECLARE @sTmp1 nvarchar(4000)
    -- This requires the Chilkat API to have been previously unlocked.
    -- See Global Unlock Sample for sample code.

    DECLARE @http int
    EXEC @hr = sp_OACreate 'Chilkat.Http', @http OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    -- Insert your AWS keys here:
    EXEC sp_OASetProperty @http, 'AwsAccessKey', 'AWS_ACCESS_KEY'
    EXEC sp_OASetProperty @http, 'AwsSecretKey', 'AWS_SECRET_KEY'

    DECLARE @bucketName nvarchar(4000)
    SELECT @bucketName = 'chilkat.ocean'
    DECLARE @objectName nvarchar(4000)
    SELECT @objectName = 'seahorse.jpg'

    -- User-defined metadata are name/value pairs, and are returned in the HTTP response header.
    -- Metadata header names begin with "x-amz-meta-" to distinguish them from other HTTP headers.
    -- Note that Amazon S3 stores user-defined metadata keys in lowercase.

    -- A HEAD request can be sent to return the response header without the response body.
    -- The S3_FileExists method sends a HEAD request.
    -- It can be used to get the response header.
    DECLARE @retval int
    EXEC sp_OAMethod @http, 'S3_FileExists', @retval OUT, @bucketName, @objectName
    IF @retval < 0
      BEGIN

        PRINT 'Failed to check for the S3 object existence'
        EXEC sp_OAGetProperty @http, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @http
        RETURN
      END
    IF @retval = 0
      BEGIN

        PRINT 'The S3 object does not exist.'
        EXEC @hr = sp_OADestroy @http
        RETURN
      END

    -- The response header is available in the LastResponseHeader property.
    DECLARE @responseHeader nvarchar(4000)
    EXEC sp_OAGetProperty @http, 'LastResponseHeader', @responseHeader OUT

    PRINT 'Response header:'

    PRINT @responseHeader

    PRINT '--'

    -- Here is an example response header:

    -- 	x-amz-id-2: uS4Flff04M8x5YWajU231TP0ClBL19mMhuyfU5ZVQd6NsUHXVhHK+H3b0sjxY98Fujet1ejhyzk=
    -- 	x-amz-request-id: 27950009AA8E68AA
    -- 	Date: Mon, 23 Jan 2017 20:12:58 GMT
    -- 	Last-Modified: Fri, 20 Jan 2017 00:22:57 GMT
    -- 	ETag: "a8551f0a5437f43a796fca7623ee9232"
    -- 	x-amz-meta-species: big-belly seahorse
    -- 	x-amz-meta-genus: Hippocampus
    -- 	x-amz-meta-habitat: shallow tropical and temperate waters
    -- 	Accept-Ranges: bytes
    -- 	Content-Type: image/jpg
    -- 	Content-Length: 24388
    -- 	Server: AmazonS3

    -- HTTP requests and responses are MIME.  For easy parsing, the response header
    -- can be loaded into a Chilkat MIME object
    DECLARE @mime int
    EXEC @hr = sp_OACreate 'Chilkat.Mime', @mime OUT

    DECLARE @success int
    EXEC sp_OAMethod @mime, 'LoadMime', @success OUT, @responseHeader

    -- Examine the metadata values:

    EXEC sp_OAMethod @mime, 'GetHeaderField', @sTmp0 OUT, 'x-amz-meta-species'
    PRINT 'x-amz-meta-species: ' + @sTmp0

    EXEC sp_OAMethod @mime, 'GetHeaderField', @sTmp0 OUT, 'x-amz-meta-genus'
    PRINT 'x-amz-meta-genus: ' + @sTmp0

    EXEC sp_OAMethod @mime, 'GetHeaderField', @sTmp0 OUT, 'x-amz-meta-habitat'
    PRINT 'x-amz-meta-habitat: ' + @sTmp0

    PRINT '--'

    -- It is possible to iterate over the header fields to find all x-amz-meta* headers
    DECLARE @i int
    SELECT @i = 0
    DECLARE @numHeaders int
    EXEC sp_OAGetProperty @mime, 'NumHeaderFields', @numHeaders OUT
    DECLARE @sbName int
    EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sbName OUT

    WHILE @i < @numHeaders
      BEGIN
        EXEC sp_OAMethod @mime, 'GetHeaderFieldName', @sTmp0 OUT, @i
        EXEC sp_OAMethod @sbName, 'SetString', @success OUT, @sTmp0
        EXEC sp_OAMethod @sbName, 'StartsWith', @iTmp0 OUT, 'x-amz-meta', 0
        IF @iTmp0 = 1
          BEGIN
            EXEC sp_OAMethod @sbName, 'GetAsString', @sTmp0 OUT

            EXEC sp_OAMethod @mime, 'GetHeaderFieldValue', @sTmp1 OUT, @i
            PRINT @sTmp0 + ': ' + @sTmp1
          END
        SELECT @i = @i + 1
      END

    -- The output:

    -- 	x-amz-meta-species: big-belly seahorse
    -- 	x-amz-meta-genus: Hippocampus
    -- 	x-amz-meta-habitat: shallow tropical and temperate waters

    EXEC @hr = sp_OADestroy @http
    EXEC @hr = sp_OADestroy @mime
    EXEC @hr = sp_OADestroy @sbName


END
GO