用于 PostgresNIO 的宏。
@Statement(_:)1
从被修饰的查询字符串创建一个 PostgresPreparedStatement。
import PostgresNIO
import PostgresNIOMacros
@Statement("SELECT \("id", UUID.self), \("name", String.self), \("age", Int.self) FROM users WHERE \(bind: "age", Int.self) < age")
struct UsersStatement {}
let connection: PostgresConnection = ...
let stream = try await connection.execute(UsersStatement(age: 18), logger: ...)
for try await user in stream {
print(user.id, user.name, user.age)
}
展开后的源代码。
struct UsersStatement {
struct Row {
var id: UUID
var name: String
var age: Int
}
static let sql = "SELECT id, name, age FROM users WHERE $1 < age"
var age: Int
func makeBindings() throws -> PostgresBindings {
var bindings = PostgresBindings(capacity: 1)
bindings.append(age)
return bindings
}
func decodeRow(_ row: PostgresRow) throws -> Row {
let (id, name, age) = try row.decode((UUID, String, Int).self)
return Row(id: id, name: name, age: age)
}
}
extension UsersStatement: PostgresPreparedStatement {}
脚注
-
这个宏最初是由 @fabianfett 向我提出的。↩