/// <summary>
/// Asynchronously creates a <see cref="RecordSetReader"/> instance capable to read <paramref name="provider"/>
/// execution results and bound to the specified <paramref name="context"/>.
/// </summary>
/// <param name="context">The <see cref="EnumerationContext"/> instance associated with the query execution.</param>
/// <param name="provider">The <see cref="ExecutableProvider"/> to be processed.</param>
/// <param name="token">The <see cref="CancellationToken"/> allowing to cancel query execution if necessary.</param>
/// <returns><see cref="RecordSetReader"/> instance ready for enumeration.
/// This means query is already executed but no records have been read yet.</returns>
public static async ValueTask <RecordSetReader> CreateAsync(
EnumerationContext context, ExecutableProvider provider, CancellationToken token)
{
var recordSet = new RecordSetReader(context, provider, token);
await recordSet.Prepare(true).ConfigureAwait(false);
return(recordSet);
}
/// <summary>
/// Creates a <see cref="RecordSetReader"/> instance capable to read <paramref name="provider"/>
/// execution results and bound to the specified <paramref name="context"/>.
/// </summary>
/// <param name="context">The <see cref="EnumerationContext"/> instance associated with the query execution.</param>
/// <param name="provider">The <see cref="ExecutableProvider"/> to be processed.</param>
/// <returns><see cref="RecordSetReader"/> instance ready for enumeration.
/// This means query is already executed but no records have been read yet.</returns>
public static RecordSetReader Create(EnumerationContext context, ExecutableProvider provider)
{
var recordSet = new RecordSetReader(context, provider);
var task = recordSet.Prepare(false);
task.GetAwaiter().GetResult(); // Ensure exception, if any, is being thrown
return(recordSet);
}
/// <summary>
/// Converts the <see cref="RecordSetReader"/> items to <see cref="Entity"/> instances.
/// </summary>
/// <param name="source">The <see cref="RecordSetReader"/> to process.</param>
/// <param name="primaryKeyIndex">Index of primary key within the <see cref="Record"/>.</param>
/// <returns>The sequence of <see cref="Entity"/> instances.</returns>
public static IEnumerable <Entity> ToEntities(this RecordSetReader source, int primaryKeyIndex)
{
var session = ((EnumerationContext)source.Context).Session;
var reader = session.Domain.EntityDataReader;
foreach (var record in reader.Read(source.ToEnumerable(), source.Header, session))
{
var key = record.GetKey(primaryKeyIndex);
if (key == null)
{
continue;
}
var tuple = record.GetTuple(primaryKeyIndex);
if (tuple != null)
{
yield return(session.Handler.UpdateState(key, tuple).Entity);
}
else
{
yield return(session.Query.SingleOrDefault(key));
}
}
}
/// <summary>
/// Converts the <see cref="RecordSetReader"/> items to <see cref="Entity"/> instances.
/// </summary>
/// <typeparam name="T">The type of <see cref="Entity"/> instances to get.</typeparam>
/// <param name="source">The <see cref="RecordSetReader"/> to process.</param>
/// <param name="primaryKeyIndex">Index of primary key within the <see cref="Record"/>.</param>
/// <returns>The sequence of <see cref="Entity"/> instances.</returns>
public static IEnumerable <T> ToEntities <T>(this RecordSetReader source, int primaryKeyIndex)
where T : class, IEntity =>
ToEntities(source, primaryKeyIndex).Cast <T>();