カラム名の衝突や順番依存の設計リスクを解消する
L columnsにcolumのorderを値として持つようにする
#[derive(Debug)]
struct ColumnSchema {
order: usize,
column_type: ColumnType,
}
#[derive(Debug)]
struct Columns {
schema: HashMap<String, ColumnSchema>,
order: Vec<String>,
}
利用側
fn main() {
let mut schema = HashMap::new();
let mut order = vec![];
let columns = vec![
("id", ColumnType::Integer),
("name", ColumnType::Text),
("age", ColumnType::Integer),
];
for (i, (name, col_type)) in columns.into_iter().enumerate() {
schema.insert(name.to_string(), ColumnSchema {
order: i,
column_type: col_type,
});
order.push(name.to_string());
}
let columns = Columns { schema, order };
let mut table = Table {
name: "users".to_string(),
columns: columns,
rows: vec![],
};
let result = table.insert_row(vec![
Value::Integer(1),
Value::Text("Alice".to_string()),
Value::Integer(30),
]);
let result = table.insert_row(vec![
Value::Integer(2),
Value::Text("Bob".to_string()),
Value::Integer(25),
]);
println!("{:?}", table);
let _ = table.update_value_by_column_condition(
"id",
&Value::Integer(2),
"name",
Value::Text("Carol".to_string()),
);
// let matching_rows = table.find_rows_by_column_value("id", &Value::Integer(2));
// for row in matching_rows {
// println!("Matched row: {:?}", row);
// }
// let matching_rows = table.find_rows_by_column_value("id", &Value::Integer(2));
// for row in matching_rows {
// println!("Matched row: {:?}", row);
// }
let _ = table.delete_rows_by_column_value("id", &Value::Integer(2));
println!("{:?}", table);
}
Table { name: “users”, columns: Columns { schema: {“age”: ColumnSchema { order: 2, column_type: Integer }, “name”: ColumnSchema { order: 1, column_type: Text }, “id”: ColumnSchema { order: 0, column_type: Integer }}, order: [“id”, “name”, “age”] }, rows: [[Integer(1), Text(“Alice”), Integer(30)], [Integer(2), Text(“Bob”), Integer(25)]] }
Table { name: “users”, columns: Columns { schema: {“age”: ColumnSchema { order: 2, column_type: Integer }, “name”: ColumnSchema { order: 1, column_type: Text }, “id”: ColumnSchema { order: 0, column_type: Integer }}, order: [“id”, “name”, “age”] }, rows: [[Integer(1), Text(“Alice”), Integer(30)]] }
なるほど、ある程度期待通りになっています。
