Get stock data from the unofficial Yahoo web API

This will access the unofficial Yahoo web API. There API may not be available in the future.

Using Hilres.YahooFinance

There are two function that will retrieve the historical stock prices.

• GetPricesAsync
• GetPricesParserAsync

YahooClient class

This YahooClient class should be created only once when the application is started. The logger is optional.

public YahooClient(ILogger? logger = null)

Example using logging in a console appliction

using Hilres.YahooFinanceClient;

private static class Program
{
    private static async Task Main()
    {
        using var loggerFactory = LoggerFactory.Create(builder =>
        {
            builder
                .AddFilter("Microsoft", LogLevel.Warning)
                .AddFilter("System", LogLevel.Warning)
                .AddConsole();
        });
        ILogger logger = loggerFactory.CreateLogger<Program>();
        logger.LogInformation("Start");

        var client = new YahooClient(loggerFactory.CreateLogger<YahooClient>());

        /* more code */

        logger.LogInformation("End");
    }
}

GetPricesAsync function

This will retrieve a IEnumerable<YahooPrice> price list.

public async Task<YahooPricesResult> GetPricesAsync(
    string symbol,
    DateOnly? firstDate = null,
    DateOnly? lastDate = null,
    YahooInterval interval = YahooInterval.Daily,
    CancellationToken cancellationToken = default)

Example:

var client = new YahooClient();
var response = await client.GetPricesAsync("msft", new(2022, 1, 3), new(2022, 1, 8));

if (response.IsSuccessful)
{
    foreach (var item in response.Prices)
    {
        Console.WriteLine(item);
    }
}

GetPricesParserAsync function

This will retrive a IAsyncEnumerable<YahooPriceParser> price list. YahooPriceParser is used to convert the data and is not an object to use. The IAsyncEnumerable can only be used once and then the connection is closed.

public async Task<YahooPricesParserResult> GetPricesParserAsync(
    string symbol,
    DateOnly? firstDate = null,
    DateOnly? lastDate = null,
    YahooInterval interval = YahooInterval.Daily,
    CancellationToken cancellationToken = default)

Example:

var parser = await client.GetPricesParserAsync("msft", new(2022, 1, 3), new(2022, 1, 8));
if (parser.IsSuccessful)
{
    var prices = await parser.Prices
            .Select(p => new MyPrice(p.Date, p.AdjClose, p.Volume))
            .ToDictionaryAsync(p => p.Date)
            .ConfigureAwait(false);

    Console.WriteLine(prices[new(2022, 1, 4)]);
    Console.WriteLine(prices[new(2022, 1, 6)]);
}

public record MyPrice(DateOnly Date, double? AdjClose, long? Volume);

The cool thing about GetPricesParserAsync is that it minimizes creating extra objects. In this case, the values are going directly into the dictionary. GetPricesAsync is a warper that calls GetPricesParserAsync