Modeling a Hive Metastore Table Schema in Python

from dataclasses import dataclass, field
from typing import Dict, List, Optional


@dataclass
class HiveTable:
    """Simple mock of a Hive metastore table schema."""
    name: str
    database: str = "default"
    columns: List[Dict[str, str]] = field(default_factory=list)
    partition_keys: List[Dict[str, str]] = field(default_factory=list)
    storage_format: str = "TEXTFILE"
    location: Optional[str] = None

    @property
    def column_names(self) -> List[str]:
        return [col["name"] for col in self.columns]

    @property
    def partition_names(self) -> List[str]:
        return [pk["name"] for pk in self.partition_keys]

    def add_column(self, name: str, col_type: str) -> None:
        self.columns.append({"name": name, "type": col_type})

    def add_partition_key(self, name: str, col_type: str) -> None:
        self.partition_keys.append({"name": name, "type": col_type})

    def describe(self) -> str:
        schema = [
            f"Database: {self.database}",
            f"Table: {self.name}",
            f"Format: {self.storage_format}",
            "Columns: " + ", ".join(
                f"{c['name']} {c['type']}" for c in self.columns
            ),
            "Partitions: " + (
                ", ".join(
                    f"p['name']} {p['type']}" for p in self.partition_keys
                )
                if self.partition_keys
                else "None"
            ),
        ]
        if self.location:
            schema.append(f"Location: {self.location}")
        return "\n".join(schema)


if __name__ == "__main__":
    table = HiveTable("sales_events")
    table.add_column("event_id", "STRING")
    table.add_column("amount", "DECIMAL(10,2)")
    table.add_column("customer_id", "BIGINT")
    table.add_partition_key("event_date", "DATE")

    print(table.describe())