[explore ] templating can now reference query elements (#2388)

Second take on
mistercrunch#3

superset/connectors/sqla/models.py

@@ -340,8 +340,15 @@ def get_query_str(  # sqla
             extras=None,
             columns=None):
         """Querying any sqla table from this common interface"""
+        template_kwargs = {
+            'from_dttm': from_dttm,
+            'groupby': groupby,
+            'metrics': metrics,
+            'row_limit': row_limit,
+            'to_dttm': to_dttm,
+        }
         template_processor = get_template_processor(
-            table=self, database=self.database)
+            table=self, database=self.database, **template_kwargs)
 
         # For backward compatibility
         if granularity not in self.dttm_cols:
@@ -430,7 +437,8 @@ def visit_column(element, compiler, **kw):
 
         # Supporting arbitrary SQL statements in place of tables
         if self.sql:
-            tbl = TextAsFrom(sa.text(self.sql), []).alias('expr_qry')
+            from_sql = template_processor.process_template(self.sql)
+            tbl = TextAsFrom(sa.text(from_sql), []).alias('expr_qry')
 
         if not columns:
             qry = qry.group_by(*groupby_exprs)

superset/jinja_context.py

@@ -44,7 +44,7 @@ class BaseTemplateProcessor(object):
     """
     engine = None
 
-    def __init__(self, database=None, query=None, table=None):
+    def __init__(self, database=None, query=None, table=None, **kwargs):
         self.database = database
         self.query = query
         self.schema = None
@@ -53,20 +53,22 @@ def __init__(self, database=None, query=None, table=None):
         elif table:
             self.schema = table.schema
         self.context = {}
+        self.context.update(kwargs)
         self.context.update(BASE_CONTEXT)
         if self.engine:
             self.context[self.engine] = self
         self.env = SandboxedEnvironment()
 
-    def process_template(self, sql):
+    def process_template(self, sql, **kwargs):
         """Processes a sql template
 
         >>> sql = "SELECT '{{ datetime(2017, 1, 1).isoformat() }}'"
         >>> process_template(sql)
         "SELECT '2017-01-01T00:00:00'"
         """
         template = self.env.from_string(sql)
-        return template.render(self.context)
+        kwargs.update(self.context)
+        return template.render(kwargs)
 
 
 class PrestoTemplateProcessor(BaseTemplateProcessor):
@@ -106,6 +108,6 @@ class HiveTemplateProcessor(PrestoTemplateProcessor):
         template_processors[o.engine] = o
 
 
-def get_template_processor(database, table=None, query=None):
+def get_template_processor(database, table=None, query=None, **kwargs):
     TP = template_processors.get(database.backend, BaseTemplateProcessor)
-    return TP(database=database, table=table, query=query)
+    return TP(database=database, table=table, query=query, **kwargs)

tests/core_tests.py

@@ -553,6 +553,20 @@ def test_process_template(self):
         rendered = tp.process_template(sql)
         self.assertEqual("SELECT '2017-01-01T00:00:00'", rendered)
 
+    def test_get_template_kwarg(self):
+        maindb = self.get_main_database(db.session)
+        s = "{{ foo }}"
+        tp = jinja_context.get_template_processor(database=maindb, foo='bar')
+        rendered = tp.process_template(s)
+        self.assertEqual("bar", rendered)
+
+    def test_template_kwarg(self):
+        maindb = self.get_main_database(db.session)
+        s = "{{ foo }}"
+        tp = jinja_context.get_template_processor(database=maindb)
+        rendered = tp.process_template(s, foo='bar')
+        self.assertEqual("bar", rendered)
+
     def test_templated_sql_json(self):
         self.login('admin')
         sql = "SELECT '{{ datetime(2017, 1, 1).isoformat() }}' as test"