Add custom exceptions, simplify generation template

src/megasniff/exceptions.py

@@ -0,0 +1,22 @@
+from typing import Any, Optional
+
+
+class MissingFieldException(Exception):
+    def __init__(self, required_field: str, required_types: str):
+        message = f"No required field provided: {required_field} with type {required_types}"
+        super().__init__(message)
+        self.required_field = required_field
+        self.required_types = required_types
+
+
+class FieldValidationException(Exception):
+    def __init__(self,
+                 required_field: str,
+                 required_types: str,
+                 provided: Any,
+                 exceptions: Optional[list[Exception]] = None):
+        message = f"Required field {required_field} with type {required_types}, provided: {provided}"
+        super().__init__(message)
+        self.required_field = required_field
+        self.required_types = required_types
+        self.exceptions = exceptions or []

src/megasniff/inflator.py

@@ -17,7 +17,6 @@ class RenderData:
     argname: str
     constrs: list[tuple[str, bool]]  # typecall / use lookup table
     typename: str
-    is_union: bool
     is_optional: bool
     allow_none: bool
     default_option: Optional[str]
@@ -85,7 +84,6 @@ class SchemaInflatorGenerator:
                     argname,
                     out_argtypes,
                     repr(argtype),
-                    len(argtypes) > 1,
                     has_default,
                     allow_none,
                     default_option

src/megasniff/templates/inflator.jinja2

@@ -1,65 +1,42 @@
 {% set ns = namespace(retry_indent=0) %}
 from typing import Any
+from megasniff.exceptions import MissingFieldException, FieldValidationException
+
 def inflate(from_data: dict[str, Any]):
     from_data_keys = from_data.keys()
 
     {% for conv in conversions %}
-    {% if not conv.is_optional or conv.default_option is not none%}
     if '{{conv.argname}}' not in from_data_keys:
-        {% if not conv.is_optional %}
-        raise ValueError(f"No required field provided: {{conv.argname}} with type {{conv.typename | replace('"', "'")}}")
-        {% endif %}
-        {% if conv.default_option is not none %}
-        from_data['{{conv.argname}}'] = {{conv.default_option}}
-        {% endif%}
-    {% endif %}
-    {%endfor%}
-
-    {% for conv in conversions %}
-    conv_data = from_data['{{conv.argname}}']
-    if conv_data is None:
-    {% if not conv.allow_none %}
-        raise ValueError(f"Field {{conv.argname}} required type {{conv.typename | replace('"', "'")}}, null provided")
+    {% if conv.is_optional %}
+        {{conv.argname}} = {{conv.default_option}}
     {% else %}
-        {{conv.argname}} = None
+        raise MissingFieldException('{{conv.argname}}', "{{conv.typename | replace('"', "'")}}")
     {% endif %}
     else:
-
-        {% if conv.is_union %}
-        {% set ns.retry_indent = 0 %}
-        {% for union_type, is_builtin in conv.constrs %}
-        {{ '    ' * ns.retry_indent }}try:
-        {% if is_builtin %}
-        {{ '    ' * ns.retry_indent }}    {{conv.argname}} = {{union_type}}(conv_data)
+        conv_data = from_data['{{conv.argname}}']
+        if conv_data is None:
+        {% if not conv.allow_none %}
+            raise FieldValidationException('{{conv.argname}}', "{{conv.typename | replace('"', "'")}}", conv_data)
         {% else %}
-        {{ '    ' * ns.retry_indent }}    {{conv.argname}} = _lookup_table['{{union_type}}'](conv_data)
-        {% endif %}
-        {{ '    ' * ns.retry_indent }}except Exception as e:
-        {% set ns.retry_indent = ns.retry_indent + 1 %}
-        {% endfor %}
-        {{ '    ' * ns.retry_indent }}    raise e from e
-        {% else %}
-
-        {% if conv.constrs[0][1] %}
-        {% if conv.is_optional %}
-        if '{{conv.argname}}' not in from_data_keys:
             {{conv.argname}} = None
+        {% endif %}
         else:
-            {{conv.argname}} = {{conv.constrs[0][0]}}(conv_data)
-        {% else %}
-        {{conv.argname}} = {{conv.constrs[0][0]}}(conv_data)
-        {% endif %}
-        {% else %}
-        {% if conv.is_optional %}
-        if '{{conv.argname}}' not in from_data_keys:
-            {{conv.argname}} = None
-        else:
-            {{conv.argname}} = _lookup_table['{{conv.constrs[0][0]}}'](conv_data)
-        {% else %}
-        {{conv.argname}} = _lookup_table['{{conv.constrs[0][0]}}'](conv_data)
-        {% endif %}
-        {% endif %}
 
-        {% endif %}
+            {% set ns.retry_indent = 0 %}
+            all_conv_exceptions = []
+            {% for union_type, is_builtin in conv.constrs %}
+            {{ '    ' * ns.retry_indent }}try:
+            {% if is_builtin %}
+            {{ '    ' * ns.retry_indent }}    {{conv.argname}} = {{union_type}}(conv_data)
+            {% else %}
+            {{ '    ' * ns.retry_indent }}    {{conv.argname}} = _lookup_table['{{union_type}}'](conv_data)
+            {% endif %}
+            {{ '    ' * ns.retry_indent }}except Exception as e:
+            {{ '    ' * ns.retry_indent }}    all_conv_exceptions.append(e)
+            {% set ns.retry_indent = ns.retry_indent + 1 %}
+            {% endfor %}
+            {{ '    ' * ns.retry_indent }}raise FieldValidationException('{{conv.argname}}', "{{conv.typename | replace('"', "'")}}", conv_data, all_conv_exceptions)
+
+
     {% endfor %}
     return _tgt_type({% for conv in conversions %}{{conv.argname}}={{conv.argname}}, {% endfor %})

tests/test_basic.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 from dataclasses import dataclass
+from typing import Optional
 
 from src.megasniff import SchemaInflatorGenerator
 
@@ -32,3 +33,14 @@ def test_circular():
     a = fn({'b': {'a': None}})
 
     return isinstance(a.b, CircB)
+
+
+def test_optional():
+    @dataclass
+    class C:
+        a: Optional[int] = None
+
+    infl = SchemaInflatorGenerator()
+    fn = infl.schema_to_generator(C)
+    c = fn({})
+    assert c.a is None

tests/test_exceptions.py

@@ -0,0 +1,39 @@
+from dataclasses import dataclass
+
+import pytest
+
+from megasniff import SchemaInflatorGenerator
+from megasniff.exceptions import MissingFieldException, FieldValidationException
+
+
+def test_missing_field():
+    @dataclass
+    class A:
+        a: int
+
+    infl = SchemaInflatorGenerator()
+    fn = infl.schema_to_generator(A)
+    with pytest.raises(MissingFieldException):
+        fn({})
+
+
+def test_null():
+    @dataclass
+    class A:
+        a: int
+
+    infl = SchemaInflatorGenerator()
+    fn = infl.schema_to_generator(A)
+    with pytest.raises(FieldValidationException):
+        fn({'a': None})
+
+
+def test_invalid_field():
+    @dataclass
+    class A:
+        a: float | int | None
+
+    infl = SchemaInflatorGenerator()
+    fn = infl.schema_to_generator(A)
+    with pytest.raises(FieldValidationException):
+        fn({'a': {}})