JavaServlet Server Side Pagination

To test your backend using Postman, follow these steps:

To test your backend using Postman, follow these steps:

---

### **Step 1: Launch Postman**
Download and install [Postman](https://www.postman.com/downloads/) if you haven’t already.

---

### **Step 2: Set Up the Request**

1. **Request Type**:
   - Set the request type to `POST` since your backend expects a POST request.

2. **URL**:
   - Enter the URL of your servlet endpoint. For example:  
     ```
     http://localhost:8080/fetchTableData
     ```

3. **Headers**:
   - Add the `Content-Type` header to indicate you're sending JSON data:  
     ```
     Key: Content-Type
     Value: application/json
     ```

4. **Body**:
   - Select the **Body** tab and choose **raw**.
   - Add a JSON object as the body payload, for example:  
     ```json
     {
         "table_name": "your_table_name",
         "start": 0,
         "length": 10,
         "search": "optional_search_query"
     }
     ```

---

### **Step 3: Send the Request**

- Click **Send** to execute the POST request.

---

### **Step 4: Analyze the Response**

1. **Response Status**:
   - Ensure the response status is `200 OK`. If it's different, there might be an issue with your servlet or server configuration.

2. **Response Body**:
   - Check that the response JSON matches the expected format:
     ```json
     {
         "status": "success",
         "columns": ["id", "user_id", "ip_address", "last_login", "status", "remarks"],
         "data": [
             [2296, 167863553, "10.1.101.1", null, "0", null],
             [2297, 167863554, "10.1.101.2", "2023-11-01 12:30:00", "1", "Active"]
         ],
         "recordsTotal": 957,
         "recordsFiltered": 500
     }
     ```

3. **Common Debugging Scenarios**:
   - **Empty Response**:
     - Verify that the table name in your payload matches an actual database table.
     - Ensure your database connection is configured properly.
   - **Error Messages**:
     - Look for error messages in the response body.
     - Check your server logs for exceptions.

---

### **Advanced Testing**

1. **Test Pagination**:
   - Update `start` and `length` in the payload to test paginated responses:
     ```json
     {
         "table_name": "your_table_name",
         "start": 10,
         "length": 10,
         "search": ""
     }
     ```

2. **Test Search Functionality**:
   - Use the `search` field to filter records and verify `recordsFiltered` updates correctly:
     ```json
     {
         "table_name": "your_table_name",
         "start": 0,
         "length": 10,
         "search": "specific_value"
     }
     ```

3. **Simulate Errors**:
   - Pass an invalid `table_name` to ensure the backend handles errors gracefully:
     ```json
     {
         "table_name": "invalid_table_name",
         "start": 0,
         "length": 10,
         "search": ""
     }
     ```

---

### **Troubleshooting Tips**

1. **Backend Logs**:
   - Monitor your server logs for SQL errors or servlet exceptions.
   - Add debugging statements in your Java code to trace issues.

2. **Database Access**:
   - Verify that the database user configured in your `DatabaseConnection` class has sufficient privileges to execute queries.

3. **Firewall/Port Issues**:
   - Ensure your servlet is reachable via the port configured (e.g., `8080`) and there’s no firewall blocking it.

---

Let me know if you encounter specific errors or need further assistance!

---

Step 1: Launch Postman

Download and install Postman if you haven’t already.

---

Step 2: Set Up the Request

1. Request Type:
   • Set the request type to POST since your backend expects a POST request.
2. URL:
   • Enter the URL of your servlet endpoint. For example: http://localhost:8080/fetchTableData
3. Headers:
   • Add the Content-Type header to indicate you’re sending JSON data: Key: Content-Type Value: application/json
4. Body:
   • Select the Body tab and choose raw.
   • Add a JSON object as the body payload, for example: { "table_name": "your_table_name", "start": 0, "length": 10, "search": "optional_search_query" }

---

Step 3: Send the Request

• Click Send to execute the POST request.

---

Step 4: Analyze the Response

1. Response Status:
   • Ensure the response status is 200 OK. If it’s different, there might be an issue with your servlet or server configuration.
2. Response Body:
   • Check that the response JSON matches the expected format: { "status": "success", "columns": ["id", "user_id", "ip_address", "last_login", "status", "remarks"], "data": [ [2296, 167863553, "10.1.101.1", null, "0", null], [2297, 167863554, "10.1.101.2", "2023-11-01 12:30:00", "1", "Active"] ], "recordsTotal": 957, "recordsFiltered": 500 }
3. Common Debugging Scenarios:
   • Empty Response:
     • Verify that the table name in your payload matches an actual database table.
     • Ensure your database connection is configured properly.
   • Error Messages:
     • Look for error messages in the response body.
     • Check your server logs for exceptions.

---

Advanced Testing

1. Test Pagination:
   • Update start and length in the payload to test paginated responses: { "table_name": "your_table_name", "start": 10, "length": 10, "search": "" }
2. Test Search Functionality:
   • Use the search field to filter records and verify recordsFiltered updates correctly: { "table_name": "your_table_name", "start": 0, "length": 10, "search": "specific_value" }
3. Simulate Errors:
   • Pass an invalid table_name to ensure the backend handles errors gracefully: { "table_name": "invalid_table_name", "start": 0, "length": 10, "search": "" }

---

Troubleshooting Tips

1. Backend Logs:
   • Monitor your server logs for SQL errors or servlet exceptions.
   • Add debugging statements in your Java code to trace issues.
2. Database Access:
   • Verify that the database user configured in your DatabaseConnection class has sufficient privileges to execute queries.
3. Firewall/Port Issues:
   • Ensure your servlet is reachable via the port configured (e.g., 8080) and there’s no firewall blocking it.

---

Let me know if you encounter specific errors or need further assistance!