[utils] Fixed evaluation of multiple vars #55

Multiple variables were being evaluated with the same value
because the implementation was too naive.
This commit fixes issue #55.

netjsonconfig/utils.py

@@ -57,10 +57,20 @@ def evaluate_vars(data, context={}):
         for key, value in loop_items:
             data[key] = evaluate_vars(value, context)
     elif isinstance(data, six.string_types):
-        for var in var_pattern.findall(data):
+        vars_found = var_pattern.findall(data)
+        for var in vars_found:
             var = var.strip()
+            # if found multiple variables, create a new regexp pattern for each
+            # variable, otherwise different variables would get the same value
+            # (see https://github.com/openwisp/netjsonconfig/issues/55)
+            if len(vars_found) > 1:
+                pattern = r'\{\{(\s*%s\s*)\}\}' % var
+            # in case of single variables, use the precompiled
+            # regexp pattern to save computation
+            else:
+                pattern = var_pattern
             if var in context:
-                data = re.sub(var_pattern, context[var], data)
+                data = re.sub(pattern, context[var], data)
     return data
 
 

tests/openwrt/test_context.py

@@ -58,3 +58,22 @@ def test_no_variables_found(self):
         o = OpenWrt(config, context={"a": "b"})
         output = o.render()
         self.assertIn("option description '{{ desc }}'", output)
+
+    def test_context_bug(self):
+        """
+        see https://github.com/openwisp/netjsonconfig/issues/55
+        """
+        config = {"general": {"hostname": "test-context"}}
+        template = {
+            "files": [
+                {
+                    "path": "/etc/vpnserver1",
+                    "mode": "0644",
+                    "contents": "{{ name }}\n{{ vpnserver1 }}\n"
+                }
+            ]
+        }
+        context = {"name": "test-context",
+                   "vpnserver1": "vpn.testdomain.com"}
+        o = OpenWrt(config, context=context, templates=[template])
+        self.assertIn("vpn.testdomain.com", o.render())

tests/test_utils.py

@@ -143,5 +143,11 @@ def test_evaluate_vars_doublewhitespace(self):
     def test_evaluate_vars_strangewhitespace(self):
         self.assertEqual(evaluate_vars('{{  tz}}', {'tz': 'UTC'}), 'UTC')
 
+    def test_evaluate_vars_multiple_newline(self):
+        """
+        see https://github.com/openwisp/netjsonconfig/issues/55
+        """
+        output = evaluate_vars('{{ a }}\n{{ b }}\n', {'a': 'a', 'b': 'b'})
+        self.assertEqual(output, 'a\nb\n')
     def test_evaluate_vars_one_char(self):
         self.assertEqual(evaluate_vars('{{ a }}', {'a': 'letter-A'}), 'letter-A')