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System Providers (Assets)

LibreFolio includes two powerful "system" providers for asset pricing that do not rely on a specific external API. They provide flexibility for tracking a wide range of assets.

CSS Scraper (cssscraper)

The CSS Scraper is a versatile provider that can extract a price from any public webpage using a CSS selector.

How it Works

  1. Configuration: When assigning this provider to an asset, you must provide:

    • identifier: The URL of the webpage to scrape.
    • provider_params:
      • current_css_selector: The CSS selector to locate the price element on the page (e.g., .price-value, #stock-price).
      • currency: The currency of the price.
      • decimal_format: us (e.g., 1,234.56) or eu (e.g., 1.234,56).

  2. Execution:

    • It fetches the HTML of the specified URL.
    • It uses BeautifulSoup to parse the HTML and find the element matching the CSS selector.
    • It extracts the text content of the element and parses it into a Decimal value, handling different number formats.

Use Cases

  • Tracking the price of an asset from a financial news website.
  • Scraping data from a niche market data provider that doesn't have an API.
  • Tracking the value of a collectible from an auction site.

Limitations

  • No Historical Data: It can only fetch the current value.
  • Fragile: If the website's layout changes, the CSS selector may break.
  • Requires Public Access: It cannot access pages that require a login.

Scheduled Investment (scheduled_investment)

This is a synthetic provider that calculates the value of an asset based on a predefined interest schedule. It does not make any external calls.

How it Works

  1. Configuration: The asset's value is determined by its interest_schedule stored in the provider_params. This schedule defines:

    • Interest rate periods (start date, end date, annual rate).
    • Compounding Type: SIMPLE or COMPOUND.
    • Day Count Convention: ACT/365, ACT/360, 30/360, etc.
    • Late Interest: A separate rate to apply after the scheduled maturity date.

  2. Calculation:

    • The provider first calculates the current principal by summing up all BUY and SELL transactions for the asset.
    • It then calculates the accrued interest up to the requested date by applying the interest schedule to the principal.
    • The final value is principal + accrued_interest.

Use Cases

  • P2P/Crowdfunding Loans: Model a loan with a fixed interest rate.
  • Fixed-Rate Bonds: Calculate the value of a bond including accrued interest.
  • Any asset with predictable cash flows.

Example

If you have a P2P loan of €1,000 with a 10% simple annual interest rate, the provider will calculate its value as: - After 6 months: €1,000 (principal) + €50 (accrued interest) = €1,050. - After 1 year: €1,000 (principal) + €100 (accrued interest) = €1,100.