3.2 Handling GET Requests

In previous section, we created a simple HTTP trigger that returns a fixed string. In this section, we will create a new HTTP trigger that returns a string based on the query parameters of the request.

Say Hello To Someone

Before we start writing the code, we need to install the pydantic package in your project awel-tutorial

poetry add "pydantic>=2.6.0"

Then create a new file named http_trigger_say_hello.py in the awel_tutorial directory and add the following code:

from dbgpt._private.pydantic import BaseModel, Field
from dbgpt.core.awel import DAG, HttpTrigger, MapOperator, setup_dev_environment

class TriggerReqBody(BaseModel):
    name: str = Field(..., description="User name")
    age: int = Field(18, description="User age")

with DAG("awel_say_hello") as dag:
    trigger_task = HttpTrigger(
        endpoint="/awel_tutorial/say_hello", 
        methods="GET", 
        request_body=TriggerReqBody,
        status_code=200
    )
    task = MapOperator(
        map_function=lambda x: f"Hello, {x.name}! You are {x.age} years old."
    )
    trigger_task >> task

setup_dev_environment([dag], port=5555)

And run the following command to execute the code:

poetry run python awel_tutorial/http_trigger_say_hello.py

Now, open a new terminal and run the following command to send a GET request to the server:

curl -X GET \
"http://127.0.0.1:5555/api/v1/awel/trigger/awel_tutorial/say_hello?name=John&age=25"

The output should look like this:

"Hello, John! You are 25 years old."

Then you can stop the server by pressing Ctrl+C.

In above code, we created a TriggerReqBody class that inherits from BaseModel to define the structure of the request body. The module dbgpt._private.pydantic wraps the pydantic for the compatibility of different versions of pydantic.

When receiving a request, http trigger will parse the query parameters and build a TriggerReqBody object, then pass it to the next operator.

Return JSON Response

In previous section, we returned a string as the response. And we can also return a JSON response.

AWEL use fastapi as the default web framework, and it will automatically judge the response type of your task output, common dict, list, BaseModel of pydantic, etc. will be automatically converted to JSON response.

So if you want to return a JSON response, you can simply return a dict or a BaseModel.

Create a new file named http_trigger_say_hello_json.py in the awel_tutorial directory and add the following code:

from dbgpt._private.pydantic import BaseModel, Field
from dbgpt.core.awel import DAG, HttpTrigger, MapOperator, setup_dev_environment

class TriggerReqBody(BaseModel):
    name: str = Field(..., description="User name")
    age: int = Field(18, description="User age")

with DAG("awel_say_hello_json") as dag:
    trigger_task = HttpTrigger(
        endpoint="/awel_tutorial/say_hello_json", 
        methods="GET", 
        request_body=TriggerReqBody,
    )
    task = MapOperator(
        map_function=lambda x: {"message": f"Hello, {x.name}! You are {x.age} years old."}
    )
    trigger_task >> task

setup_dev_environment([dag], port=5555)

And run the following command to execute the code:

poetry run python awel_tutorial/http_trigger_say_hello_json.py

Now, open a new terminal and run the following command to send a GET request to the server:

curl -X GET \
"http://127.0.0.1:5555/api/v1/awel/trigger/awel_tutorial/say_hello_json?name=John&age=25"

And you will get the following output:

{"message":"Hello, John! You are 25 years old."}

Then you can stop the server by pressing Ctrl+C.