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📈 Asset Plugin Guide

How to create a new Asset Source Provider to fetch prices from a new data source.

Base class: AssetSourceProvider (in backend/app/services/asset_source.py) Plugin folder: backend/app/services/asset_source_providers/ Registry: AssetProviderRegistry

🔄 Flow

The system calls provider methods in three distinct phases:

graph TD
    subgraph "Phase 1 — Search (user looks for asset)"
        S1["search(query)<br/><small>e.g., 'Apple'</small>"] --> S2["Returns: list of<br/>{identifier, display_name,<br/>currency, type}"]
    end

    subgraph "Phase 2 — Current Price (dashboard, refresh)"
        C1["get_current_value(<br/>identifier, type, params)"] --> C2["Returns: FACurrentValue<br/><small>(price, currency, date)</small>"]
    end

    subgraph "Phase 3 — Historical Data (charts, analysis)"
        H1["get_history_value(<br/>identifier, ..., start, end)"] --> H2["Returns: FAHistoricalData<br/><small>(prices[], currency)</small>"]
        H2 --> H3["Core fills gaps<br/><small>weekends, holidays<br/>→ backward_filled=True</small>"]
    end

    S2 ~~~ C1
    C2 ~~~ H1

    style S1 fill:#e3f2fd,stroke:#1565c0
    style S2 fill:#e3f2fd,stroke:#1565c0
    style C1 fill:#e8f5e9,stroke:#2e7d32
    style C2 fill:#e8f5e9,stroke:#2e7d32
    style H1 fill:#fff3e0,stroke:#e65100
    style H2 fill:#fff3e0,stroke:#e65100
    style H3 fill:#f3e5f5,stroke:#7b1fa2

Phase 1 is optional but strongly recommended — enables users to discover and link assets without knowing the exact identifier. See Asset Search below.

Phase 2 fetches the latest price for the dashboard or manual refresh.

Phase 3 fetches historical OHLCV data. The plugin returns only actual trading days — core fills gaps (weekends, holidays) with last known value.

Plugin responsibility: Fetch raw price data from external source. Return only actual data points (trading days). Core responsibility: Gap filling (weekends/holidays → backward_filled=True), caching, database storage, currency conversion.

📋 ABC Methods

✅ Required (Abstract)

Method Signature Description
provider_code @property → str Unique identifier (e.g., "yfinance")
provider_name @property → str Display name (e.g., "Yahoo Finance")
test_cases @property → list[dict] Test cases for automated testing (identifier, identifier_type, provider_params)
test_search_query @property → str \| None Search query for automated tests. None if search not supported.
get_current_value(identifier, type, params) async → FACurrentValue Fetch latest price. Returns value, currency, as_of_date, source.
get_history_value(identifier, type, params, start, end) async → FAHistoricalData Fetch historical OHLCV data for date range. Return raw data only — no gap filling.

Implementing search() is strongly recommended

Without search, users must know the exact asset identifier (ticker, ISIN, URL) upfront. With search, they can type a name like "Apple" and pick from results.

Method Default Description
search(query) Raises NOT_SUPPORTED Search for assets by name, ticker, or ISIN. Returns [{identifier, identifier_type, display_name, currency, type}].
test_search_query — Query string for automated search tests (e.g., "Apple"). Return None if search not supported.

🔧 Optional (Override)

Method Default Description
get_icon None Provider icon URL for the UI
supports_history True Set False for providers that only support current prices (e.g., web scrapers)
validate_params(params) — Validate provider-specific configuration (raise on invalid)
generate_static_url(path) — Helper to build /api/v1/uploads/plugin/asset/{path}

The search(query) method allows users to discover assets by name, ticker, or ISIN across all providers simultaneously.

⚙️ How It Works

  1. User types a query in the UI (e.g., "Apple", "MSCI World", "IE00B4L5Y983")
  2. Frontend calls GET /api/v1/assets/provider/search?q=Apple
  3. Backend queries all providers in parallel via AssetSearchService.search() (asyncio.gather)
  4. Providers that don't implement search (default raises NOT_SUPPORTED) are silently skipped
  5. Results are aggregated and returned to the user

🔌 Provider Support

Provider search() test_search_query Notes
Yahoo Finance ✅ "Apple" Full ticker search with caching (10 min TTL)
JustETF ✅ "iShares Core S&P 500" ISIN-based search across cached ETF list
CSS Scraper ❌ None No search — URL must be provided manually
Scheduled Investment ❌ None Synthetic provider, no external search

🌐 API Endpoint

GET /api/v1/assets/provider/search?q=Apple&providers=yfinance,justetf

Query parameters:

  • q (required): Search query, min 1 character
  • providers (optional): Comma-separated provider codes. Default: all providers with search support.

Response:

{
  "query": "Apple",
  "total_results": 5,
  "results": [
    {
      "identifier": "AAPL",
      "display_name": "Apple Inc.",
      "provider_code": "yfinance",
      "currency": "USD",
      "asset_type": "stock"
    }
  ],
  "providers_queried": ["yfinance", "justetf"],
  "providers_with_errors": []
}
  • Searches are executed in parallel — one slow provider won't block others
  • Provider-specific errors are logged but don't fail the entire request
  • Errors are reported in providers_with_errors for debugging

💻 Implementation Example

# backend/app/services/asset_source_providers/my_provider.py

from datetime import date
from decimal import Decimal
from backend.app.services.asset_source import AssetSourceProvider, IdentifierType
from backend.app.services.provider_registry import register_provider, AssetProviderRegistry
from backend.app.schemas.assets import FACurrentValue, FAHistoricalData, FAPricePoint

@register_provider(AssetProviderRegistry)
class MyProvider(AssetSourceProvider):

    @property
    def provider_code(self) -> str:
        return "my_provider"

    @property
    def provider_name(self) -> str:
        return "My Data Provider"

    @property
    def test_cases(self) -> list[dict]:
        return [
            {"identifier": "AAPL", "identifier_type": IdentifierType.TICKER, "provider_params": None}
        ]

    async def get_current_value(
        self, identifier: str, identifier_type: IdentifierType, provider_params: dict
    ) -> FACurrentValue:
        # Fetch latest price from your API
        price = await self._fetch_price(identifier)
        return FACurrentValue(
            value=Decimal(str(price)),
            currency="USD",
            as_of_date=date.today(),
            source=self.provider_name,
        )

    async def get_history_value(
        self, identifier: str, identifier_type: IdentifierType,
        provider_params: dict | None, start_date: date, end_date: date
    ) -> FAHistoricalData:
        # Fetch historical data — return ONLY actual trading days
        raw_data = await self._fetch_history(identifier, start_date, end_date)
        prices = [
            FAPricePoint(date=d, close=Decimal(str(p)), open=None, high=None, low=None, volume=None)
            for d, p in raw_data
        ]
        return FAHistoricalData(prices=prices, currency="USD", source=self.provider_name)