New endpoint that receives SQL and returns data as JSON (#842)

* New endpoint that receives SQL and returns data as JSON

* Addressing comments

caravel/utils.py

@@ -319,6 +319,21 @@ def json_int_dttm_ser(obj):
     return obj
 
 
+def error_msg_from_exception(e):
+    """Translate exception into error message
+    Database have different ways to handle exception. This function attempts
+    to make sense of the exception object and construct a human readable
+    sentence.
+    """
+    msg = ''
+    if hasattr(e, 'message'):
+        if (type(e.message) is dict):
+            msg = e.message.get('message')
+        elif e.message:
+            msg = "{}".format(e.message)
+    return msg or '{}'.format(e)
+
+
 def markdown(s, markup_wrap=False):
     s = s or ''
     s = md(s, [

caravel/views.py

@@ -1214,6 +1214,7 @@ def select_star(self, database_id, table_name):
     @log_this
     def runsql(self):
         """Runs arbitrary sql and returns and html table"""
+        # TODO deprecate in favor on `sql_json`
         session = db.session()
         limit = 1000
         data = json.loads(request.form.get('data'))
@@ -1225,7 +1226,7 @@ def runsql(self):
                 not self.can_access(
                     'all_datasource_access', 'all_datasource_access')):
             raise utils.CaravelSecurityException(_(
-                "This view requires the `all_datasource_access` permission"))
+                "SQL Lab requires the `all_datasource_access` permission"))
         content = ""
         if mydb:
             eng = mydb.get_sqla_engine()
@@ -1253,6 +1254,59 @@ def runsql(self):
         session.commit()
         return content
 
+    @has_access
+    @expose("/sql_json/", methods=['POST', 'GET'])
+    @log_this
+    def sql_json(self):
+        """Runs arbitrary sql and returns and json"""
+        session = db.session()
+        limit = 1000
+        sql = request.form.get('sql')
+        database_id = request.form.get('database_id')
+        mydb = session.query(models.Database).filter_by(id=database_id).first()
+
+        if (
+                not self.can_access(
+                    'all_datasource_access', 'all_datasource_access')):
+            raise utils.CaravelSecurityException(_(
+                "This view requires the `all_datasource_access` permission"))
+
+        error_msg = ""
+        if not mydb:
+            error_msg = "The database selected doesn't seem to exist"
+        else:
+            eng = mydb.get_sqla_engine()
+            if limit:
+                sql = sql.strip().strip(';')
+                qry = (
+                    select('*')
+                    .select_from(TextAsFrom(text(sql), ['*']).alias('inner_qry'))
+                    .limit(limit)
+                )
+                sql = str(qry.compile(eng, compile_kwargs={"literal_binds": True}))
+            try:
+                df = pd.read_sql_query(sql=sql, con=eng)
+                df = df.fillna(0)  # TODO make sure NULL
+            except Exception as e:
+                logging.exception(e)
+                error_msg = utils.error_msg_from_exception(e)
+
+        session.commit()
+        if error_msg:
+            return Response(
+                json.dumps({
+                    'error': error_msg,
+                }),
+                status=500,
+                mimetype="application/json")
+        else:
+            data = {
+                'columns': [c for c in df.columns],
+                'data': df.to_dict(orient='records'),
+            }
+            return json.dumps(data, default=utils.json_int_dttm_ser, allow_nan=False)
+
+
     @has_access
     @expose("/refresh_datasources/")
     def refresh_datasources(self):

tests/core_tests.py

@@ -226,6 +226,26 @@ def test_gamma(self):
         resp = self.client.get('/dashboardmodelview/list/')
         assert "List Dashboard" in resp.data.decode('utf-8')
 
+    def run_sql(self, sql):
+        self.login(username='admin')
+        dbid = (
+            db.session.query(models.Database)
+            .filter_by(database_name="main")
+            .first().id
+        )
+        resp = self.client.post(
+            '/caravel/sql_json/',
+            data=dict(database_id=dbid, sql=sql),
+        )
+        return json.loads(resp.data.decode('utf-8'))
+
+    def test_sql_json(self):
+        data = self.run_sql("SELECT * FROM ab_user")
+        assert len(data['data']) > 0
+
+        data = self.run_sql("SELECT * FROM unexistant_table")
+        assert len(data['error']) > 0
+
     def test_public_user_dashboard_access(self):
         # Try access before adding appropriate permissions.
         self.revoke_public_access('birth_names')