fix(hana): Remove encoding from hana-client streams

hana/lib/drivers/hana-client.js

@@ -1,7 +1,6 @@
 const { Readable, Stream } = require('stream')
 
 const hdb = require('@sap/hana-client')
-const { StringDecoder } = require('string_decoder')
 const { driver, prom, handleLevel } = require('./base')
 
 const streamUnsafe = false
@@ -97,7 +96,7 @@ class HANAClientDriver extends driver {
             row[col] = i > 3 ?
               rs.isNull(i)
                 ? null
-                : Readable.from(streamBlob(rsStreams, rs._rowPosition, i, 'binary'))
+                : Readable.from(streamBlob(rsStreams, rs._rowPosition, i), { objectMode: false })
               : values[i]
           }
 
@@ -153,7 +152,7 @@ class HANAClientDriver extends driver {
         if (rs.getRowCount() === 0) return null
         await prom(rs, 'next')()
         if (rs.isNull(0)) return null
-        return Readable.from(streamBlob(rs, undefined, 0, 'binary'), { objectMode: false })
+        return Readable.from(streamBlob(rs, undefined, 0), { objectMode: false })
       }
       return Readable.from(rsIterator(rs, one), { objectMode: false })
     }
@@ -217,7 +216,8 @@ class HANAClientDriver extends driver {
       if (!curStream) continue
       for await (const chunk of curStream) {
         curStream.pause()
-        await sendParameterData(i, Buffer.from(chunk))
+        const buffer = Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk)
+        if (buffer.length) await sendParameterData(i, buffer)
         curStream.resume()
       }
       await sendParameterData(i, null)
@@ -293,7 +293,9 @@ async function* rsIterator(rs, one) {
       yield buffer
       buffer = ''
 
-      for await (const chunk of streamBlob(rs, undefined, columnIndex, 'base64', binaryBuffer)) {
+      const stream = Readable.from(streamBlob(rs, undefined, columnIndex, binaryBuffer), { objectMode: false })
+      stream.setEncoding('base64')
+      for await (const chunk of stream) {
         yield chunk
       }
       buffer += '"'
@@ -316,7 +318,7 @@ async function* rsIterator(rs, one) {
   yield buffer
 }
 
-async function* streamBlob(rs, rowIndex = -1, columnIndex, encoding, binaryBuffer = Buffer.allocUnsafe(1 << 16)) {
+async function* streamBlob(rs, rowIndex = -1, columnIndex, binaryBuffer = Buffer.allocUnsafe(1 << 16)) {
   const promChain = {
     resolve: () => { },
     reject: () => { }
@@ -357,29 +359,18 @@ async function* streamBlob(rs, rowIndex = -1, columnIndex, encoding, binaryBuffe
 
     const getData = prom(rs, 'getData')
 
-    let decoder = new StringDecoder(encoding)
-
     let blobPosition = 0
 
     while (true) {
       // REVISIT: Ensure that the data read is divisible by 3 as that allows for base64 encoding
-      let start = 0
       const read = await getData(columnIndex, blobPosition, binaryBuffer, 0, binaryBuffer.byteLength)
-      if (blobPosition === 0 && binaryBuffer.slice(0, 7).toString() === 'base64,') {
-        decoder = {
-          write: encoding === 'base64' ? c => c : chunk => Buffer.from(chunk.toString(), 'base64'),
-          end: () => Buffer.allocUnsafe(0),
-        }
-        start = 7
-      }
       blobPosition += read
       if (read < binaryBuffer.byteLength) {
-        yield decoder.write(binaryBuffer.slice(start, read))
+        yield binaryBuffer.slice(0, read)
         break
       }
-      yield decoder.write(binaryBuffer.slice(start).toString('base64'))
+      yield binaryBuffer
     }
-    yield decoder.end()
   } catch (e) {
     promChain.reject(e)
   } finally {

sqlite/test/general/stream.test.js

@@ -261,6 +261,17 @@ describe('streaming', () => {
         await checkSize(stream2_)
       }))
 
+      test('WRITE stream property from READ stream', async () => cds.tx(async () => {
+        const { Images } = cds.entities('test')
+        const { data: stream } = await SELECT.one.from(Images).columns('data').where({ ID: 1 })
+
+        const changes = await UPDATE(Images).with({ data2: stream }).where({ ID: 3 })
+        expect(changes).toEqual(1)
+
+        const [{ data2: stream_ }] = await SELECT.from(Images).columns('data2').where({ ID: 3 })
+        await checkSize(stream_)
+      }))
+
       test('WRITE multiple blob properties', async () => cds.tx(async () => {
         const { Images } = cds.entities('test')
         const blob1 = fs.readFileSync(path.join(__dirname, 'samples/test.jpg'))