Saving multiple data–part 31
I want to load the exchange rates from NBR and ECB and load at once .From here, the challenges of programming for a simple task like this:
- How we can display the errors ?
- What if the data exists already for this day and I cannot save into database, because it exists ?
- How to acknowledge what exists and what not , in one operation ?
- How to report success even if data exists ? Should we report number of records?
- How we can perform async all that stuff and, however , report errors ?
If you know the answer to all that, I have a challenge for you: see the file at https://github.com/ignatandrei/InfoValutar/blob/master/InfoValutar/InfovalutarLoadAndSave/LoadAndSaveLastData.cs– and improve it.
Until then, I come with this simple code
public class ResultsLoadBankData
{
public string Bank { get; internal set; }
public int NrRecords { get; internal set; }
public bool HasSuccess { get; internal set; }
public string ErrorMessage { get; internal set; }
}
//in some class below
public async Task<ResultsLoadBankData[]> LoadAndSave()
{
var items= providers.Banks().Select(it =>
new KeyValuePair<string, ResultsLoadBankData>(it,
new ResultsLoadBankData()
{
Bank = it,
ErrorMessage=null,
HasSuccess=true,
NrRecords=0
})
);
var lst = new Dictionary<string, ResultsLoadBankData>(items);
var rates =
providers.LoadExchange()
.Select(it => it.GetActualRates())
.ToArray();
//TODO: how to load async all async enumerables?
//TODO: how to report error if one fails?
foreach (var rateAsync in rates)
{
await foreach(var rate in rateAsync)
{
var item = lst[rate.Bank];
try
{
if (await ret.Exists(rate))
continue;
var nr = await save.Save(rate);
item.NrRecords++;
}
catch(Exception ex)
{
//TODO:log
item.ErrorMessage = ex.Message;
item.HasSuccess = false;
}
}
}
return lst.Values.ToArray();
}
Infovalutar
And one hour passes...(This is the result of 1 hour per day auto-challenge as a full cycle developer for an exchange rates application)
( You can see the sources at https://github.com/ignatandrei/InfoValutar/ )
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