dbt var 简单说明
dbt 的var 可以进行变量的定义以及变量的引用，以下简单说明下
参考使用
- 引用定义的
参考定义
name: my_dbt_project
version: 1.0.0
config-version: 2
# Define variables here
vars:
event_type: activation
select * from events where event_type = '{{ var("event_type") }}'
- 定义
包含了默认值
select * from events where event_type = '{{ var("event_type", "activation") }}'
{%- set concat_string = var('concat_string', '||') -%}
内部处理
实际上就是一个属性,会包含cli 以及context 中的一些信息
@contextproperty()
def var(self) -> Var:
"""Variables can be passed from your `dbt_project.yml` file into models
during compilation. These variables are useful for configuring packages
for deployment in multiple environments, or defining values that should
be used across multiple models within a package.
To add a variable to a model, use the `var()` function:
> my_model.sql:
select * from events where event_type = '{{ var("event_type") }}'
If you try to run this model without supplying an `event_type`
variable, you'll receive a compilation error that looks like this:
Encountered an error:
! Compilation error while compiling model package_name.my_model:
! Required var 'event_type' not found in config:
Vars supplied to package_name.my_model = {
}
To supply a variable to a given model, add one or more `vars`
dictionaries to the `models` config in your `dbt_project.yml` file.
These `vars` are in-scope for all models at or below where they are
defined, so place them where they make the most sense. Below are three
different placements of the `vars` dict, all of which will make the
`my_model` model compile.
> dbt_project.yml:
# 1) scoped at the model level
models:
package_name:
my_model:
materialized: view
vars:
event_type: activation
# 2) scoped at the package level
models:
package_name:
vars:
event_type: activation
my_model:
materialized: view
# 3) scoped globally
models:
vars:
event_type: activation
package_name:
my_model:
materialized: view
## Variable default values
The `var()` function takes an optional second argument, `default`. If
this argument is provided, then it will be the default value for the
variable if one is not explicitly defined.
> my_model.sql:
-- Use 'activation' as the event_type if the variable is not
-- defined.
select *
from events
where event_type = '{{ var("event_type", "activation") }}'
"""
return Var(self._ctx, self.cli_vars)
