Merge branch 'f-etag' into 'dev'

ENH: etag property for the query

See merge request caosdb/caosdb-pylib!55

CHANGELOG.md

@@ -9,6 +9,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added ###
 
+* `etag` property for the `caosdb.Query` class. The etag allows to debug the
+  caching and to decide whether the server has changed between queries.
+
 ### Changed ###
 
 ### Deprecated ###

src/caosdb/common/models.py

@@ -3661,6 +3661,7 @@ class Query():
         self.flags = dict()
         self.messages = _Messages()
         self.cached = None
+        self.etag = None
 
         if isinstance(q, etree._Element):
             self.q = q.get("string")
@@ -3670,6 +3671,7 @@ class Query():
                 self.cached = False
             else:
                 self.cached = q.get("cached").lower() == "true"
+            self.etag = q.get("etag")
 
             for m in q:
                 if m.tag.lower() == 'warning' or m.tag.lower() == 'error':
@@ -3714,6 +3716,7 @@ class Query():
         cresp = Container._response_to_entities(http_response)
         self.results = cresp.query.results
         self.cached = cresp.query.cached
+        self.etag = cresp.query.etag
 
         if self.q.lower().startswith('count') and len(cresp) == 0:
             # this was a count query

unittests/test_query.py

@@ -26,20 +26,23 @@ import caosdb as db
 
 
 def test_query_parsing():
-    s = '<Query string="FIND bla" results="0" cached="true"/>'
+    s = '<Query string="FIND bla" results="0" cached="true" etag="asdf"/>'
     q = db.Query(etree.fromstring(s))
     assert q.q == "FIND bla"
     assert q.results == 0
     assert q.cached is True
+    assert q.etag == "asdf"
 
-    s = '<Query string="COUNT bla" results="1" cached="false"/>'
+    s = '<Query string="COUNT bla" results="1" cached="false" etag="asdf"/>'
     q = db.Query(etree.fromstring(s))
     assert q.q == "COUNT bla"
     assert q.results == 1
     assert q.cached is False
+    assert q.etag == "asdf"
 
     s = '<Query string="COUNT blub" results="4"/>'
     q = db.Query(etree.fromstring(s))
     assert q.q == "COUNT blub"
     assert q.results == 4
     assert q.cached is False
+    assert q.etag is None