static async Task UpdateCurrencies(RatesContext context, IDictionary <string, string> symbols)
{
var currencies = await context.Currencies.ToListAsync();
var toUpdate = new List <Currency>();
var toAdd = new List <Currency>();
foreach ((var symbol, var name) in symbols)
{
var currency = currencies.SingleOrDefault(c => c.Symbol == symbol);
if (currency is null)
{
currency = new Currency {
Symbol = symbol, FullName = name
};
toAdd.Add(currency);
}
else
{
currency.FullName = name;
toUpdate.Add(currency);
}
}
context.AddRange(toAdd);
context.UpdateRange(toUpdate);
await context.SaveChangesAsync();
}
public async Task SaveChanges()
{
await context.SaveChangesAsync();
}