Implement skip_if field attribute

Author: yukinarit

README.md

@@ -61,7 +61,8 @@ From Json: Hoge(i=10, s='hoge', f=100.0, b=True)
 	* [Case conversion](#case-conversion) e.g. camelCase, kebab-case
 * Field attributes
     * [Rename](#rename-field)
-    * [Skip](#skip-field)
+    * [Skip](#skip)
+    * [Skip-if](#skip-if)
     * [Skip if value is evaluated as False](#skip-if-value-is-evaluated-as-false)
 
 ### Case conversion
@@ -91,7 +92,7 @@ From Json: Hoge(i=10, s='hoge', f=100.0, b=True)
 
 For complete example, please see [./examples/rename.py](./examples/rename.py)
 
-### Skip field
+### Skip
 
 ```python
 >>> @serialize
@@ -110,6 +111,26 @@ For complete example, please see [./examples/rename.py](./examples/rename.py)
 
 For complete example, please see [./examples/skip.py](./examples/skip.py)
 
+### Skip if
+
+```python
+>>> @serialize
+... @dataclass
+... class World:
+...     player: str
+...     buddy: str = field(default='', metadata={'serde_skip_if': lambda v: v == 'Pikachu'})
+
+>>> world = World('satoshi', 'Pikachu')
+>>> to_json(world)
+'{"player": "satoshi"}'
+
+>>> world = World('green', 'Charmander')
+>>> print(to_json(world))
+'{"player": "green", "buddy": "Charmander"}'
+```
+
+For complete example, please see [./examples/skip.py](./examples/skip.py)
+
 ### Skip if value is evaluated as False
 
 ```python

examples/skip.py

@@ -27,6 +27,7 @@ class Resource:
 class World:
     player: str
     enemies: List[str] = field(default_factory=list, metadata={'serde_skip_if_false': True})
+    buddy: str = field(default='', metadata={'serde_skip_if': lambda v: v == 'Pikachu'})
 
 
 def main():
@@ -36,10 +37,10 @@ def main():
     ]
     print(to_json(resources))
 
-    world = World('satoshi', ['Rattata', 'Pidgey'])
+    world = World('satoshi', ['Rattata', 'Pidgey'], 'Pikachu')
     print(to_json(world))
 
-    world = World('green', [])
+    world = World('green', [], 'Charmander')
     print(to_json(world))
 
 

examples/yamlfile.py

@@ -8,7 +8,7 @@
     $ pipenv run yamlfile.py
 """
 from typing import List, Dict, Optional, Union
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from serde import deserialize
 from serde.yaml import from_yaml
 
@@ -25,8 +25,7 @@ class Info:
 @dataclass
 class Parameter:
     name: str
-    # in is reserved keyword.
-    # in: str
+    infield: str = field(metadata={'serde_rename': 'in'})
     type: str
     required: bool
 

serde/se.py

@@ -8,8 +8,10 @@
 from dataclasses import Field as DataclassField
 from dataclasses import asdict as _asdict
 from dataclasses import astuple as _astuple
-from dataclasses import dataclass, fields as dataclass_fields, is_dataclass
-from typing import Any, ClassVar, Dict, List, Optional, Tuple, Type
+from dataclasses import dataclass
+from dataclasses import fields as dataclass_fields
+from dataclasses import is_dataclass
+from typing import Any, Callable, ClassVar, Dict, Iterator, List, Optional, Tuple, Type
 
 import jinja2
 import stringcase
@@ -75,8 +77,13 @@ def serialize(self, ser, **opts) -> None:
             return ser.serialize(self, **opts)
 
         setattr(cls, SE_NAME, serialize)
-        cls = se_func(cls, TO_ITER, render_astuple(cls))
-        cls = se_func(cls, TO_DICT, render_asdict(cls, rename_all))
+
+        g: Dict[str, Any] = globals().copy()
+        for f in fields(cls):
+            if f.skip_if:
+                g[f.skip_if.mangled] = f.skip_if
+        cls = se_func(cls, TO_ITER, render_astuple(cls), g)
+        cls = se_func(cls, TO_DICT, render_asdict(cls, rename_all), g)
         return cls
 
     if _cls is None:
@@ -185,11 +192,28 @@ class Field:
     case: Optional[str] = None
     rename: Optional[str] = None
     skip: Optional[bool] = None
+    skip_if: Optional[Callable[[Any], bool]] = None
     skip_if_false: Optional[bool] = None
 
     @staticmethod
     def from_dataclass(f: DataclassField) -> '':
-        return Field(f.type, f.name, rename = f.metadata.get('serde_rename'), skip = f.metadata.get('serde_skip'), skip_if_false = f.metadata.get('serde_skip_if_false'))
+        if f.metadata.get('serde_skip_if_false'):
+            skip_if_false = lambda v: not bool(v)
+            skip_if_false.mangled = Field.mangle(f, 'skip_if')
+        else:
+            skip_if_false = None
+
+        skip_if = f.metadata.get('serde_skip_if')
+        if skip_if:
+            skip_if.mangled = Field.mangle(f, 'skip_if')
+
+        return Field(
+            f.type,
+            f.name,
+            rename=f.metadata.get('serde_rename'),
+            skip=f.metadata.get('serde_skip'),
+            skip_if=skip_if or skip_if_false,
+        )
 
     @property
     def varname(self) -> str:
@@ -203,9 +227,13 @@ def __getitem__(self, n) -> 'Field':
         typ = type_args(self.type)[n]
         return Field(typ, None)
 
+    @staticmethod
+    def mangle(field: DataclassField, name: str) -> str:
+        return f'{field.name}_{name}'
+
 
-def fields(cls: Type) -> List[Field]:
-    return [Field.from_dataclass(f) for f in dataclass_fields(cls)]
+def fields(cls: Type) -> Iterator[Field]:
+    return iter(Field.from_dataclass(f) for f in dataclass_fields(cls))
 
 
 def to_arg(f: Field) -> Field:
@@ -248,14 +276,16 @@ def {{func}}(obj):
   {% if cls|is_dataclass %}
   res = {}
   {% for f in cls|fields -%}
-  {% if not f.skip|default(False) %}
-    {% if f.skip_if_false|default(False) %}
-  if {{f|arg|rvalue()}}:
+
+  {% if not f.skip %}
+    {% if f.skip_if %}
+  if not {{f.skip_if.mangled}}({{f|arg|rvalue()}}):
     res["{{f|case}}"] = {{f|arg|rvalue()}}
     {% else %}
   res["{{f|case}}"] = {{f|arg|rvalue()}}
     {% endif %}
   {% endif %}
+
   {% endfor -%}
   return res
   {% endif %}
@@ -359,16 +389,18 @@ def primitive(self, arg: Field) -> str:
         return f'{arg.varname}'
 
 
-def se_func(cls: Type[T], func: str, code: str) -> Type[T]:
+def se_func(cls: Type[T], func: str, code: str, g: Dict = None, local: Dict = None) -> Type[T]:
     """
     Generate function to serialize into an object.
     """
-    g: Dict[str, Any] = globals().copy()
-
     # Generate serialize function.
-    code = gen(code, g, cls=cls)
+    if not g:
+        g = globals().copy()
+    if not local:
+        local = locals().copy()
+    code = gen(code, g, local, cls=cls)
 
-    setattr(cls, func, g[func])
+    setattr(cls, func, local[func])
     if SETTINGS['debug']:
         hidden = getattr(cls, HIDDEN_NAME)
         hidden.code[func] = code

serde/toml.py

@@ -20,7 +20,7 @@ def deserialize(cls, s, **opts):
         return toml.loads(s)
 
 
-def to_toml(obj, se: Type[TomlSerializer]=TomlSerializer) -> str:
+def to_toml(obj, se: Type[TomlSerializer] = TomlSerializer) -> str:
     """
     Take an object and return toml string.