added setter for increment value

Richard Kooijman · Richard Kooijman · commit c637198da631 · 2021-01-03T00:25:16.000+01:00
added test for this functionality
diff --git a/tableaudocumentapi/datasource.py b/tableaudocumentapi/datasource.py
@@ -274,6 +274,8 @@ def parameters(self):
 
     @property
     def extract(self):
+        if not self.has_extract():
+            return None
         return self._extract[0]
 
     def _get_all_fields(self):
diff --git a/tableaudocumentapi/extract.py b/tableaudocumentapi/extract.py
@@ -29,6 +29,11 @@ def units(self):
     def connection(self):
         return self._connection[0]
 
+    def has_refresh(self):
+        return len(self._refresh) > 0
+
     @property
     def refresh(self):
+        if not self.has_refresh():
+            return None
         return self._refresh[0]
