Add checks for redundant fields in codegen-ed code (#169)

* Move attrs to a class variable in codegen

Author: tom-tan

schema_salad/codegen.py

@@ -90,7 +90,13 @@ def codegen(lang,             # type: str
 
                 cg.declare_field(fieldpred, tl, f.get("doc"), optional)
 
-            cg.end_class(rec["name"])
+            field_names = []
+            for f in rec.get("fields", []):
+                jld = f.get("jsonldPredicate")
+                name = f["name"]
+                field_names.append(shortname(name))
+
+            cg.end_class(rec["name"], field_names)
 
     rootType = list(documentRoots)
     rootType.append({

schema_salad/codegen_base.py

@@ -38,8 +38,8 @@ def begin_class(self, classname, extends, doc, abstract):
         # type: (Text, List[Text], Text, bool) -> None
         raise NotImplementedError()
 
-    def end_class(self, classname):
-        # type: (Text) -> None
+    def end_class(self, classname, field_names):
+        # type: (Text, List[Text]) -> None
         raise NotImplementedError()
 
     def type_loader(self, t):

schema_salad/java_codegen.py

@@ -68,7 +68,7 @@ def begin_class(self, classname, extends, doc, abstract):
     void Load() {
 """)
 
-    def end_class(self, classname):
+    def end_class(self, classname, field_names):
         with open(os.path.join(self.outdir, "%s.java" % self.current_class), "a") as f:
             f.write("""
 }

schema_salad/python_codegen.py

@@ -88,18 +88,27 @@ def save(self):
         r = {}
 """)
 
-    def end_class(self, classname):
-        # type: (Text) -> None
+    def end_class(self, classname, field_names):
+        # type: (Text, List[Text]) -> None
 
         if self.current_class_is_abstract:
             return
 
         self.out.write("""
+        for k in doc.keys():
+            if k not in self.attrs:
+                errors.append(SourceLine(doc, k, str).makeError("invalid field `%s`, expected one of: {attrstr}" % (k)))
+                break
+
         if errors:
-            raise ValidationException(\"Trying '%s'\\n\"+\"\\n\".join(errors))
-""" % self.safe_name(classname))
+            raise ValidationException(\"Trying '{class_}'\\n\"+\"\\n\".join(errors))
+""".
+                       format(attrstr=", ".join(["`%s`" % f for f in field_names]),
+                              class_=self.safe_name(classname)))
+        self.serializer.write("        return r\n\n")
+
+        self.serializer.write("    attrs = frozenset({attrs})\n".format(attrs=field_names))
 
-        self.serializer.write("        return r\n")
         self.out.write(self.serializer.getvalue())
         self.out.write("\n\n")