`amount_from_string` requires `_args` in `oxylabs` v2.0.0 despite documentation/examples

[ryullulala]

Description:

When using amount_from_string in parsing_instructions with oxylabs version 2.0.0, the library's internal validation (oxylabs/utils/utils.py) unexpectedly requires a non-empty string for _args. This contradicts the official documentation examples (e.g., [insert link to relevant documentation if available, or describe where you saw the example]), which show amount_from_string being used without an _args parameter.

Problem:

The validate_fn_args function, specifically when calling validate_string for fn_name.AMOUNT_FROM_STRING, enforces that _args must be a non-empty string. If _args is not provided (as per the documentation examples), a ValueError: _args must be a non-empty string is raised.

Affected Library Version:

• oxylabs version: 2.0.0

Steps to Reproduce:

1. Install oxylabs v2.0.0:

   uv pip install oxylabs==2.0.0

2. Create a Python script (e.g., test_oxylabs.py) with the following content:

   from oxylabs import RealtimeClient
   
   username = "YOUR_OXYLABS_USERNAME"
   password = "YOUR_OXYLABS_PASSWORD"
   
   parsing_instructions_with_error = {
       "total_count": {
           "_fns": [
               {
                   "_fn": "xpath_one",
                   "_args": [".//span[contains(@class, 'total-results')]/text()"]
               },
               {
                   "_fn": "amount_from_string"  # This line causes the error
               }
           ]
       }
   }
   parsing_instructions_no_error = {
       "total_count": {
           "_fns": [
               {
                   "_fn": "xpath_one",
                   "_args": [".//span[contains(@class, 'total-results')]/text()"]
               },
               {
                   "_fn": "amount_from_string", "_args": "dummy" 
               }
           ]
       }
   }
   
   client = RealtimeClient(username, password)
   try:
       result = client.universal.scrape_url(
           "https://google.com",
           parse=True,
           parsing_instructions=parsing_instructions_with_error,
           render="html",
       )
       print(result)
   except ValueError as e:
       print(f"An error occurred: {e}")

3. Replace "YOUR_OXYLABS_USERNAME" and "YOUR_OXYLABS_PASSWORD" with valid Oxylabs credentials.

4. Run the script:

   python test_oxylabs.py

Expected Behavior:

The script should execute without a ValueError and the amount_from_string function should process the extracted text as per its intended functionality, consistent with how it's presented in the documentation examples without an explicit _args requirement.

Actual Behavior:

A ValueError: _args must be a non-empty string is raised due to the internal validation for amount_from_string.

Suggested Resolution (Optional):

Either update the oxylabs library to remove the _args requirement for amount_from_string (if it's not functionally needed), or update the documentation to clearly state that _args is a mandatory parameter for this function in parsing_instructions.

Reference

• https://developers.oxylabs.io/scraping-solutions/web-scraper-api/features/result-processing-and-storage/custom-parser/list-of-functions/function-examples#amount_from_string