Feat/json serialize or expression (apache#2565)

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Closes apache#2519

# Rationale for this change

## Are these changes tested?
yes

## Are there any user-facing changes?

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Author: jaimeferj

pyiceberg/expressions/__init__.py

@@ -33,7 +33,7 @@
 )
 from typing import Literal as TypingLiteral
 
-from pydantic import Field
+from pydantic import ConfigDict, Field
 
 from pyiceberg.expressions.literals import (
     AboveMax,
@@ -302,12 +302,19 @@ def __getnewargs__(self) -> Tuple[BooleanExpression, BooleanExpression]:
         return (self.left, self.right)
 
 
-class Or(BooleanExpression):
+class Or(IcebergBaseModel, BooleanExpression):
     """OR operation expression - logical disjunction."""
 
+    model_config = ConfigDict(arbitrary_types_allowed=True)
+
+    type: TypingLiteral["or"] = Field(default="or", alias="type")
     left: BooleanExpression
     right: BooleanExpression
 
+    def __init__(self, left: BooleanExpression, right: BooleanExpression, *rest: BooleanExpression) -> None:
+        if isinstance(self, Or) and not hasattr(self, "left") and not hasattr(self, "right"):
+            super().__init__(left=left, right=right)
+
     def __new__(cls, left: BooleanExpression, right: BooleanExpression, *rest: BooleanExpression) -> BooleanExpression:  # type: ignore
         if rest:
             return _build_balanced_tree(Or, (left, right, *rest))
@@ -319,10 +326,12 @@ def __new__(cls, left: BooleanExpression, right: BooleanExpression, *rest: Boole
             return left
         else:
             obj = super().__new__(cls)
-            obj.left = left
-            obj.right = right
             return obj
 
+    def __str__(self) -> str:
+        """Return the string representation of the Or class."""
+        return f"{str(self.__class__.__name__)}(left={repr(self.left)}, right={repr(self.right)})"
+
     def __eq__(self, other: Any) -> bool:
         """Return the equality of two instances of the Or class."""
         return self.left == other.left and self.right == other.right if isinstance(other, Or) else False

tests/expressions/test_expressions.py

@@ -714,6 +714,17 @@ def test_or() -> None:
         null | "abc"  # type: ignore
 
 
+def test_or_serialization() -> None:
+    left = EqualTo("a", 10)
+    right = EqualTo("b", 20)
+    or_ = Or(left, right)
+
+    assert (
+        or_.model_dump_json()
+        == '{"type":"or","left":{"term":"a","type":"eq","value":10},"right":{"term":"b","type":"eq","value":20}}'
+    )
+
+
 def test_not() -> None:
     null = IsNull(Reference("a"))
     not_ = Not(null)