from pyetl import Task, DatabaseReader, DatabaseWriter
reader = DatabaseReader("sqlite:///db1.sqlite3", table_name="source")
writer = DatabaseWriter("sqlite:///db2.sqlite3", table_name="target")
Task(reader, writer).start()

from pyetl import Task, DatabaseReader, HiveWriter2
reader = DatabaseReader("sqlite:///db1.sqlite3", table_name="source")
writer = HiveWriter2("hive://localhost:10000/default", table_name="target")
Task(reader, writer).start()

from pyetl import Task, DatabaseReader, ElasticSearchWriter
reader = DatabaseReader("sqlite:///db1.sqlite3", table_name="source")
writer = ElasticSearchWriter(hosts=["localhost"], index_name="tartget")
Task(reader, writer).start()

# 原始表source包含uuid，full_name字段
reader = DatabaseReader("sqlite:///db.sqlite3", table_name="source")
# 目标表target包含id，name字段
writer = DatabaseWriter("sqlite:///db.sqlite3", table_name="target")
# columns配置目标表和原始表的字段映射关系
columns = {"id": "uuid", "name": "full_name"}
Task(reader, writer, columns=columns).start()

# functions配置字段的udf映射，如下id转字符串，name去除前后空格
functions={"id": str, "name": lambda x: x.strip()}
Task(reader, writer, columns=columns, functions=functions).start()

import json
from pyetl import Task, DatabaseReader, DatabaseWriter

class NewTask(Task):
  reader = DatabaseReader("sqlite:///db.sqlite3", table_name="source")
  writer = DatabaseWriter("sqlite:///db.sqlite3", table_name="target")
  
  def get_columns(self):
    """通过函数的方式生成字段映射配置，使用更灵活"""
    # 以下示例将数据库中的字段映射配置取出后转字典类型返回
    sql = "select columns from task where name='new_task'"
    columns = self.writer.db.read_one(sql)["columns"]
    return json.loads(columns)
   
  def get_functions(self):
    """通过函数的方式生成字段的udf映射"""
    # 以下示例将每个字段类型都转换为字符串
    return {col: str for col in self.columns}
   
  def apply_function(self, record):
    """数据流中对一整条数据的udf"""
    record["flag"] = int(record["id"]) % 2
    return record

  def before(self):
    """任务开始前要执行的操作, 如初始化任务表，创建目标表等"""
    sql = "create table destination_table(id int, name varchar(100))"
    self.writer.db.execute(sql)
  
  def after(self):
    """任务完成后要执行的操作，如更新任务状态等"""
    sql = "update task set status='done' where name='new_task'"
    self.writer.db.execute(sql)

NewTask().start()