A Guide to Pagination in the 3dcart API: Fetching Sales Data
Tags: api, python, webdev, beginners
Published: 2023-07-04 19:11:48


## Introduction
Working with APIs often involves retrieving large amounts of data. To efficiently handle all of this data, pagination is a crucial technique. This article aims to guide you through the process of implementing pagination with the 3dcart API, using a Python script as an example. By the end, you'll have a clear understanding of how to fetch sales data from the 3dcart API using pagination.

## Prerequisites
Before diving into pagination, ensure you have the following prerequisites:


0. Basic knowledge of Python programming.
1. Familiarity with making API requests using Python.

## Setting Up the Script
To begin, let's set up a script that fetches sales data from the 3dcart API. The script provided below serves as a starting point:

```
# Import the necessary libraries
import requests
import json
import time

def fetch_sales_data_from_api(sales_order_names):
    # Load headers from the config file
    with open('config.json') as config_file:
        config = json.load(config_file)

    # Set up the base URL and headers
    base_url = "https://apirest.3dcart.com/3dCartWebAPI/v1/Orders"
    headers = {
        'SecureURL': config['SecureURL'],
        'PrivateKey': config['PrivateKey'],
        'Token': config['Token']
    }

    # Set pagination parameters
    limit = 100  # Number of results per page
    offset = 0   # Initial offset value
    max_retries = 3

    all_order_data = []

    # Iterate over the order statuses
    for order_status in sales_order_names:
        # Remove the "WH-" prefix from the order status
        invoice_number = order_status.replace("WH-", "")

        # Reset the offset for each order status
        offset = 0

        # Construct the initial URL
        url = f"{base_url}?invoicenumber={invoice_number}&limit={limit}&offset={offset}"

        # Retry logic
        success = False
        retries = 0

        while not success and retries < max_retries:
            response = requests.request("GET", url, headers=headers)

            if response.status_code == 200:
                success = True
                print(f"Successfully fetched data from {url}")
                orders = response.json()
                if orders:
                    all_order_data.extend(orders)
                break

            else:
                print("Retrying...")
                retries += 1
                time.sleep(10)

        if not success:
            print("Failed to fetch data after multiple retries.")

    return all_order_data
```



# What is Pagination ?

Pagination is a technique used to retrieve large amounts of data in manageable chunks or pages. The 3dcart API supports pagination by allowing you to specify the `limit` and `offset` parameters in your API requests.

* The `limit` parameter determines the number of results per page.
* The `offset` parameter indicates the starting position of the data to be retrieved.

Basically think of pagination as breaking up large chunks of data to sort data faster. 

## Implementing Pagination

In the provided script, pagination is implemented in the `fetch_sales_data_from_api` function. Here's a breakdown of how it works:

1. The script loads the necessary headers from a configuration file (`config.json`).
2. It sets up the base URL and constructs the headers for the API request.
3. Pagination parameters are defined:
    * `limit`: The number of results to retrieve per page. In the example, it's set to 100.
    * `offset`: The initial starting position. It's reset for each order status in the loop.
4. The script initializes an empty list, `all_order_data`, to store the fetched order data.
5. For each order status, the script constructs the URL by combining the base URL, the invoice number (with the "WH-" prefix removed), the limit, and the offset.
6. A retry loop is implemented to handle potential failures during the API request. It tries up to `max_retries` times, with a 10-second delay between retries.
7. Upon a successful response (status code 200), the script extracts the orders data from the response and appends it to the `all_order_data` list.
8. If the maximum number of retries is reached without success, an appropriate message is printed.
9. Finally, the function returns the complete `all_order_data` list.

## Conclusion

In this article, we explored how to implement pagination when working with the 3dcart API. By using the provided script as a starting point, you can fetch sales data from the API while handling pagination seamlessly. Remember to adapt the script and configuration file to suit your specific requirements.

Pagination is a powerful technique that allows you to work with large datasets more efficiently. With this knowledge, you're now equipped to fetch data from the 3dcart API using pagination effectively.

Here is a gist of the code
https://gist.github.com/tunahorse/01d74fd67af06b625ce5c59481f906d9

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