Testing Invoice File Upload

Prerequisites

• Postman installed (https://www.postman.com/downloads).

Resource Preparation

Download the following files before testing the API in Postman:

• demo_invoice.png
• demo_invoice2.png
• demo_invoice3.png

Step 1: Convert Images to Base64

We will use the online tool base64-image.de:

1. Visit the website and select the file demo_invoice.png.

2. The website will automatically convert it to Base64.

3. Click </> show code to retrieve the Base64 string.

4. Copy the Base64 code.

5. Save it temporarily in Notepad.

6. Repeat the process for the remaining two files.

Step 2: Create a Postman Collection

1. Open the Postman application.

2. Click the "+" button to create a new collection.

3. Select Blank Collection.

4. Name it: InvoiceUploadAPI-Tests

Step 3: Create a Request

1. Inside the newly created collection, click the "+" button to add a request.

2. Name the request: Upload Invoice.

3. Select the POST method.

5. Go to API Gateway, select the API: PostInvoiceAPI.

6. Navigate to the Stages section.

7. Click the “+” button to reveal the full URL.

8. Select the POST method and copy the Invoke URL.

9. Paste the Invoke URL into Postman as shown:

10. Go to the Headers tab and configure as follows:

Content-Type: application/json

11. Navigate to the Body tab → Select raw → Choose JSON.

12. Paste the following JSON into Postman:

{
    "file": "",
    "filename": ""
}

13. Paste the Base64 string saved earlier in Notepad and specify the filename as follows:

14. Click the Send button to view the results.

15. A successful response will appear as follows:

16. Go to S3 → Navigate to the uploads/ folder → Verify the uploaded file.

17. Access DynamoDB → Select Explore items → Choose the InvoiceData table.