export/import column map support

packages/api/src/utility/ColumnMapTransformStream.js

@@ -0,0 +1,21 @@
+const stream = require('stream');
+const { transformRowUsingColumnMap } = require('dbgate-tools');
+
+class ColumnMapTransformStream extends stream.Transform {
+  constructor(columns) {
+    super({ objectMode: true });
+    this.columns = columns;
+  }
+  _transform(chunk, encoding, done) {
+    if (chunk.__isStreamHeader) {
+      // skip stream header
+      done();
+      return;
+    }
+
+    this.push(transformRowUsingColumnMap(chunk, this.columns));
+    done();
+  }
+}
+
+module.exports = ColumnMapTransformStream;