dbt exceptions macro 简单说明

dbt exceptions 实际属于一个namespace 变量可以进行一些代码可控的异常处理以及raise 以及warn

参考使用

• raise_compiler_error 使用

{% if number < 0 or number > 100 %}

  {{ exceptions.raise_compiler_error("Invalid `number`. Got: " ~ number) }}

{% endif %}

内部实现

属于一个上下文属性

• 参考代码

@contextproperty()

def exceptions(self) -> Dict[str, Any]:

    """The exceptions namespace can be used to raise warnings and errors in

    dbt userspace.

 

 

    ## raise_compiler_error

 

    The `exceptions.raise_compiler_error` method will raise a compiler

    error with the provided message. This is typically only useful in

    macros or materializations when invalid arguments are provided by the

    calling model. Note that throwing an exception will cause a model to

    fail, so please use this variable with care!

 

    Example usage:

 

    > exceptions.sql:

 

        {% if number < 0 or number > 100 %}

          {{ exceptions.raise_compiler_error("Invalid `number`. Got: " ~ number) }}

        {% endif %}

 

    ## warn

 

    The `exceptions.warn` method will raise a compiler warning with the

    provided message. If the `--warn-error` flag is provided to dbt, then

    this warning will be elevated to an exception, which is raised.

 

    Example usage:

 

    > warn.sql:

 

        {% if number < 0 or number > 100 %}

          {% do exceptions.warn("Invalid `number`. Got: " ~ number) %}

        {% endif %}

    """  # noqa

    return wrapped_exports(self.model)

• wrapped_exports 处理
  实际上就是一个装饰器，可以将信息包装起来，方便显示

def wrapper(model):

    def wrap(func):

        @functools.wraps(func)

        def inner(*args, **kwargs):

            try:

                return func(*args, **kwargs)

            except DbtRuntimeError as exc:

                exc.add_node(model)

                raise exc

 

        return inner

 

    return wrap

 

 

def wrapped_exports(model):

    wrap = wrapper(model)

    return {name: wrap(export) for name, export in CONTEXT_EXPORTS.items()}

说明

exceptions 对于我们可以稳健的模型还是比较方便的，可以尽早失败，dbt 的return 实现了一种尽早返回数据的能力

参考资料

https://docs.getdbt.com/reference/dbt-jinja-functions/exceptions