error messages for jsonschema validation and return code

recipes.py

@@ -1,3 +1,4 @@
+import sys
 from typing import Dict, List, Any, Optional, Set
 import os
 import json
@@ -5,6 +6,7 @@ import json
 import yaml
 import jinja2
 import jsonschema
+import jsonschema.exceptions
 
 
 class Context:
@@ -12,6 +14,7 @@ class Context:
         self.units = Units()
         self.ingredients = Ingredients(self)
 
+
 class Conversion:
     def load(self, units: List["Unit"], dct: Dict[str, Any]) -> None:
         def find_unit(name: str) -> Optional[Unit]:
@@ -32,6 +35,7 @@ class Conversion:
 
         self.ratio = dct["ratio"]
 
+
 class Unit:
     def load(self, units: List["Unit"], dct: Dict[str, Any]) -> None:
         self.name = dct["name"]
@@ -43,7 +47,9 @@ class Unit:
         if "conversions" in dct:
             for convdct in dct["conversions"]:
                 if "from" in dct["conversions"]:
-                    raise RuntimeError(f"conversions in units.yaml cannot have a from field, it is automatically assigned from the unit name")
+                    raise RuntimeError(
+                        f"conversions in units.yaml cannot have a from field, it is automatically assigned from the unit name"
+                    )
                 convdct["from"] = self.name
                 conversion = Conversion()
                 conversion.load(unitsx, convdct)
@@ -267,6 +273,7 @@ class Builder:
             loader=jinja2.FileSystemLoader("templates"),
             autoescape=jinja2.select_autoescape(),
         )
+
         def numprint(input: int) -> str:
             out = str(input)
             if out.endswith(".0"):
@@ -279,7 +286,7 @@ class Builder:
                 return "3/4"
             return out
 
-        self.jinjaenv.filters['numprint'] = numprint
+        self.jinjaenv.filters["numprint"] = numprint
         self.ctx = Context()
         # list of output files that will be built
         self.outfiles: Set[str] = set()
@@ -305,25 +312,30 @@ class Builder:
             f.write(outstr)
         self.outfiles.add(file)
 
-    def load(self) -> None:
+    def load(self) -> int:
         issues: List[str] = []
 
         unitsdct = self.load_file("recipes/units.yaml")
         unitsschema = self.load_file("schemas/units.json")
         jsonschema.validate(instance=unitsdct, schema=unitsschema)
         issues += self.ctx.units.load(unitsdct)
+        if len(issues) != 0:
+            for issue in issues:
+                print("ERROR in units.yaml:", issue)
+            return 1
 
         ingredientsdct = self.load_file("recipes/ingredients.yaml")
         ingredientsschema = self.load_file("schemas/ingredients.json")
         jsonschema.validate(instance=ingredientsdct, schema=ingredientsschema)
         issues += self.ctx.ingredients.load(ingredientsdct)
-
         if len(issues) != 0:
             for issue in issues:
-                print("ERROR", issue)
-            return
+                print("ERROR in ingredients.yaml:", issue)
+            return 1
 
-    def run(self) -> None:
+        return 0
+
+    def run(self) -> int:
         issues = []
         files = []
         for _, _, filesx in os.walk("recipes/recipes"):
@@ -347,15 +359,16 @@ class Builder:
         if len(issues) != 0:
             for issue in issues:
                 print("ERROR", issue)
-            return
+            return 1
 
         self.rendertemplate("index.html", "html", "index.html", {"recipes": recipes})
         for recipe in recipes:
             self.rendertemplate(
                 "recipe.html", "html", recipe.outpath, {"recipe": recipe}
             )
+        return 0
 
-    def finish(self) -> None:
+    def finish(self) -> int:
         files = set()
         for _, _, filesx in os.walk("out/html"):
             files = set(filesx)
@@ -365,13 +378,21 @@ class Builder:
         for file in extra_files:
             print(f"removing obsolete {file}")
             os.remove(f"out/html/{file}")
+        return 0
 
-    def main(self) -> None:
-        self.load()
-        self.run()
-        self.finish()
+    def main(self) -> int:
+        fcs = [self.load, self.run, self.finish]
+        for func in fcs:
+            try:
+                ret = func()
+                if ret != 0:
+                    return ret
+            except jsonschema.exceptions.ValidationError as e:
+                print("ERROR:", e)
+                return 1
+        return 0
 
 
 if __name__ == "__main__":
     builder = Builder()
-    builder.main()
+    sys.exit(builder.main())