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Rest api

This module provides the RestApiReader class for interacting with RESTful APIs.

The RestApiReader class is designed to fetch data from RESTful APIs and store the response in a DataFrame. It supports different transports, e.g. Paginated Http or Async HTTP. The main entry point is the execute method, which performs transport.execute() call and provide data from the API calls.

For more details on how to use this class and its methods, refer to the class docstring.

koheesio.spark.readers.rest_api.RestApiReader #

A reader class that executes an API call and stores the response in a DataFrame.

Parameters:

Name Type Description Default
transport Union[InstanceOf[AsyncHttpGetStep], InstanceOf[HttpGetStep]]

The HTTP transport step.

 required
spark_schema Union[str, StructType, List[str], Tuple[str, ...], AtomicType]

The pyspark schema of the response.

 required

Attributes:

Name Type Description
transport Union[InstanceOf[AsyncHttpGetStep], InstanceOf[HttpGetStep]]

The HTTP transport step.
spark_schema Union[str, StructType, List[str], Tuple[str, ...], AtomicType]

The pyspark schema of the response.

Returns:

Type Description
Output

The output of the reader, which includes the DataFrame.

Examples:

Here are some examples of how to use this class:

Example 1: Paginated Transport 

import requests
from urllib3 import Retry

from koheesio.steps.http import HttpGetStep
from koheesio.spark.readers.rest_api import RestApiReader

session = requests.Session()
retry_logic = Retry(total=max_retries, status_forcelist=[503])
session.mount("https://", HTTPAdapter(max_retries=retry_logic))
session.mount("http://", HTTPAdapter(max_retries=retry_logic))

transport = PaginatedHttpGetStep(
    url="https://api.example.com/data?page={page}",
    paginate=True,
    pages=3,
    session=session,
)
task = RestApiReader(transport=transport, spark_schema="id: int, page:int, value: string")
task.execute()
all_data = [row.asDict() for row in task.output.df.collect()]

Example 2: Async Transport 

from aiohttp import ClientSession, TCPConnector
from aiohttp_retry import ExponentialRetry
from yarl import URL

from koheesio.steps.asyncio.http import AsyncHttpGetStep
from koheesio.spark.readers.rest_api import RestApiReader

session = ClientSession()
urls = [URL("http://httpbin.org/get"), URL("http://httpbin.org/get")]
retry_options = ExponentialRetry()
connector = TCPConnector(limit=10)
transport = AsyncHttpGetStep(
    client_session=session,
    url=urls,
    retry_options=retry_options,
    connector=connector,
)

task = RestApiReader(transport=transport, spark_schema="id: int, page:int, value: string")
task.execute()
all_data = [row.asDict() for row in task.output.df.collect()]

spark_schema class-attribute instance-attribute #

spark_schema: Union[
    str, StructType, List[str], Tuple[str, ...], AtomicType
] = Field(
    ..., description="The pyspark schema of the response"
)

transport class-attribute instance-attribute #

transport: Union[
    InstanceOf[AsyncHttpGetStep], InstanceOf[HttpGetStep]
] = Field(
    ..., description="HTTP transport step", exclude=True
)

execute #

execute() -> Output

Executes the API call and stores the response in a DataFrame.

Returns:

Type Description
Output

The output of the reader, which includes the DataFrame.
Source code in src/koheesio/spark/readers/rest_api.py 
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def execute(self) -> Reader.Output:
    """
    Executes the API call and stores the response in a DataFrame.

    Returns
    -------
    Reader.Output
        The output of the reader, which includes the DataFrame.
    """
    raw_data = self.transport.execute()

    data = None
    if isinstance(raw_data, HttpGetStep.Output):
        data = raw_data.response_json
    elif isinstance(raw_data, AsyncHttpGetStep.Output):
        data = [d for d, _ in raw_data.responses_urls]  # type: ignore

    if data:
        self.output.df = self.spark.createDataFrame(data=data, schema=self.spark_schema)  # type: ignore