First steps in checking user-supplied filters

Checks for `=` and `__` in the filter
Checks that the relationship is valid

docs/user/filtering.rst

@@ -49,7 +49,7 @@ relation        description
 ==============  ========================================================
 ``startswith``  All fields starting by the target
 ``endswith``    All fields ending by the target
-``exacts``      Exact matching
+``exact``       Exact matching
 ``contains``    Fields that contain the target
 ``range``       Fields with values in the range
 ``gt``          Field with values greater than the target

pymangal/checks.py

@@ -56,12 +56,33 @@ def check_filters(filters):
 
     :param filters: A string of filters
 
-    :returns: Nothing, but can modify ``filters`` in place
+    :returns: Nothing, but can modify ``filters`` in place, and raises ``ValueError``s if the filters are badly formatted.
 
-    At the moment, this function do not parse the filters to make sure that they are valid.
+    This functions conducts minimal parsing, to make sure that the relationship exists, and that the filter is generally well formed.
 
     The ``filters`` string is modified in place if it contains space.
     """
     if not isinstance(filters, str):
         raise TypeError("filters must be a string")
+    # We replace all spaces with %20
     filters.replace(' ', '%20')
+    # These steps will check that the filters are correct
+    REL = ['sartswith', 'endswith', 'exact', 'contains', 'range', 'gt', 'lt', 'gte', 'lte', 'in']
+    filters = filters.split('&')
+    for fi in filters:
+        if not '=' in fi:
+            raise ValueError("Filter "+fi+" is invalid (no =)")
+        if not '__' in fi:
+            raise ValueError("Filter "+fi+" is invalid (no __)")
+        splitted_filter = fi.split('=')
+        match = splitted_filter[0]
+        target = splitted_filter[1]
+        request = match.split('__')
+        relationship = request[len(request)-1]
+        if not relationship in REL:
+            raise ValueError("Filter "+fi+" is invalid ("+ relationship +" is not a valid relationship)")
+    if len(filters) == 1 :
+        return filters
+    else :
+        return '&'.join(filters)
+

test_pymangal.py

@@ -143,6 +143,15 @@ def test_filters_is_str(self):
     def test_filters_space_replaced(self):
         assert isinstance(self.mg.List('taxa', 'name__contains=s b'), dict)
 
+    def test_filters_valid_relationship(self):
+        self.assertRaises(ValueError, lambda : self.mg.List('taxa', 'name__islike=Lame'))
+
+    def test_filters_valid_structure(self):
+        self.assertRaises(ValueError, lambda : self.mg.List('taxa', 'name__contains=a&name_endswith=s'))
+
+    def test_filters_has_equal_sign(self):
+        self.assertRaises(ValueError, lambda : self.mg.List('taxa', 'name__contains_i'))
+
     def test_resource_available(self):
         self.assertRaises(ValueError, lambda : self.mg.List('TAXA'))