Question

I am new to EF. I created entity models from database.

I have tables CurrencyMaster([FromCurrency],[ToCurrency],[ActiveStatus]) and CurrencyConversion([ID],[FromCurrency],[ToCurrency],[Date],[CurrencyFactor])

I am looping for the CurrencyMaster records and accordingly DownloadCurrencyRates will get me the List<CurrencyRate> objects.
I just want to add these objects to entity database.

I tried something like this

public DownloadStatus DownloadUpdateCurrency(DateTime toDate, DateTime fromDate)
{
    CurrencyEntities db = new CurrencyEntities();
    var curMasters = db.CurrencyMasters.Where(x => x.ActiveStatus == 0);
    foreach (var item in curMasters)
    {

        var curcRatesList = DownloadCurrencyRates(fromDate, toDate, 
                                          item.FromCurrency, item.ToCurrency);

        //I know this is a bad code
        curcRatesList.Select(x =>  
                              {   
                                  db.AddToCurrencyConversions(
                                     new CurrencyEntity.CurrencyConversion { 
                                        Date = x.date, 
                                        CurrencyFactor = x.value, 
                                        FromCurrency = item.FromCurrency, 
                                        ToCurrency = item.ToCurrency 
                                      }
                                  ); 
                                  return true; 
                              }); 
    }
    db.SaveChanges();
    return DownloadStatus.DownloadSuccess;
}

How can I do the same in a proper way?
Is there any way I can do this without looping for curcRatesList?

I am using .NET 3.5, and not sure about EF version.. I didn’t try executing code(I need some other setup for that), but I am quite sure that what I am doing is not correct.. So I am posting here..

Answer 1

The procedure is correct. There is no bulk insert capability in EF that would allow to add a whole list of entities in a single method call. You must loop over the items and add them one by one.

As a side note: I would just use an ordinary foreach loop instead of that strange Select trick (which misuses the Select method, but it will work). Or – if curcRatesList is of type List<T> – you can use the Foreach method of List<T> instead of Select.