/// <summary>
/// Starts 1 async fetch request for each cohort endpoint e.g. NormalCohorts ExternalCohortTable database contains 100 cohorts while FreakyCohorts ExternalCohortTable database
/// has another 30.
///
/// <para>These async requests are managed by the CohortDescriptionDataTableAsyncFetch object which has a callback for compeltion. Each ExtractableCohortDescription subscribes to
/// the callback to self populate</para>
/// </summary>
/// <returns></returns>
public Dictionary <CohortDescriptionDataTableAsyncFetch, ExtractableCohortDescription[]> Create()
{
var toReturn = new Dictionary <CohortDescriptionDataTableAsyncFetch, ExtractableCohortDescription[]>();
foreach (ExternalCohortTable source in _sources)
{
//setup the async data retreival which can take a long time if there are a lot of cohorts or millions of identifiers
var asyncFetch = new CohortDescriptionDataTableAsyncFetch(source);
var cohorts = _cohorts.Where(c => c.ExternalCohortTable_ID == source.ID).Select(c => new ExtractableCohortDescription(c, asyncFetch)).ToArray();
asyncFetch.Begin();
toReturn.Add(asyncFetch, cohorts);
}
return(toReturn);
}
/// <summary>
/// Creates a new description based on the async fetch request for all cohorts including row counts etc (which might have already completed btw). If you
/// use this constructor then the properties will start out with text like "Loading..." but it will perform much faster, when the fetch completes the
/// values will be populated. In general if you want to use this feature you should probably use CohortDescriptionFactory and only use it if you are
/// trying to get all the cohorts at once.
///
/// </summary>
/// <param name="cohort"></param>
/// <param name="fetch"></param>
public ExtractableCohortDescription(ExtractableCohort cohort, CohortDescriptionDataTableAsyncFetch fetch)
{
Cohort = cohort;
Fetch = fetch;
OriginID = cohort.OriginID;
Count = -1;
CountDistinct = -1;
SourceName = fetch.Source.Name;
try
{
ReleaseIdentifier = cohort.GetReleaseIdentifier(true);
}
catch (Exception)
{
ReleaseIdentifier = "Unknown";
}
try
{
PrivateIdentifier = cohort.GetPrivateIdentifier(true);
}
catch (Exception)
{
PrivateIdentifier = "Unknown";
}
ProjectNumber = -1;
Version = -1;
Description = "Loading...";
//if it's already finished
if (fetch.Task != null && fetch.Task.IsCompleted)
{
FetchOnFinished();
}
else
{
fetch.Finished += FetchOnFinished;
}
}
