/// <summary>
/// The get data async.
/// </summary>
/// <param name="context">
/// The context.
/// </param>
/// <param name="multiPartQuery">
/// The multi part query.
/// </param>
/// <returns>
/// The <see cref="Task"/>.
/// </returns>
internal override IAsyncEnumerable <Row> GetRows(IInternalExecutionContext context, [NotNull] IMultiPartQuery multiPartQuery)
{
var fieldReplacer = GenericVisitor.Create((SourceFieldExpression e) => CustomExpression.MakeField(e.SourceName, e.FieldName, e.Type));
var query =
multiPartQuery.WildcardAliases.Contains(this.alias) ?
new Query(
fieldReplacer.Visit(multiPartQuery.FilterExpression),
multiPartQuery.OrderByExpressions.Select(o => new OrderByExpression(fieldReplacer.Visit(o.Expression), o.Ascending)),
multiPartQuery.Count)
: new Query(
multiPartQuery.Fields.Where(f => f.SourceAlias == this.alias).Select(f => f.FieldName),
fieldReplacer.Visit(multiPartQuery.FilterExpression),
multiPartQuery.OrderByExpressions.Select(o => new OrderByExpression(fieldReplacer.Visit(o.Expression), o.Ascending)),
multiPartQuery.Count);
var rowBuilder = new RowBuilder(this.alias);
return(context
.CreateAsyncEnumerable(async() => (await this.selectPlan.ExecuteAsync(context)).QueryResults.First().Rows)
.Select(rowBuilder.Attach)
.Where(query.GetFilter(context)?.GetRowFilter())
.OrderBy(query.GetSortOrders(context)));
}
/// <summary>
/// The get rows.
/// </summary>
/// <param name="context">
/// The context.
/// </param>
/// <param name="multiPartQuery">
/// The multi-part query.
/// </param>
/// <returns>
/// The <see cref="IAsyncEnumerable{Row}"/>.
/// </returns>
internal override IAsyncEnumerable <Row> GetRows([NotNull] IInternalExecutionContext context, [NotNull] IMultiPartQuery multiPartQuery)
{
var functionName = context.GetDisplayName(this.dataSource);
var fieldReplacer = GenericVisitor.Create((SourceFieldExpression e) => CustomExpression.MakeField(e.SourceName, e.FieldName, e.Type));
var query =
multiPartQuery.WildcardAliases.Contains(this.alias) ?
new Query(
fieldReplacer.Visit(multiPartQuery.FilterExpression),
multiPartQuery.OrderByExpressions.Select(o => new OrderByExpression(fieldReplacer.Visit(o.Expression), o.Ascending)),
multiPartQuery.Count)
: new Query(
multiPartQuery.Fields.Where(f => f.SourceAlias == this.alias).Select(f => f.FieldName),
fieldReplacer.Visit(multiPartQuery.FilterExpression),
multiPartQuery.OrderByExpressions.Select(o => new OrderByExpression(fieldReplacer.Visit(o.Expression), o.Ascending)),
multiPartQuery.Count);
Expression unsupportedFilters = null;
IOrderByExpression[] unsupportedOrderByExpressions = null;
// ReSharper disable once SuspiciousTypeConversion.Global, implemented in other assemblies.
var expressionSupport = this.dataSource as IDataSourceFilterSupport;
if (expressionSupport != null)
{
var parts = query.FilterExpression.SplitByAndExpressions().Cast <CompareExpression>().ToArray();
var filters = parts.ToLookup(p => expressionSupport.SupportsExpression(p), e => (Expression)e);
var supportedFilter = filters[true].DefaultIfEmpty().Aggregate(Expression.AndAlso);
unsupportedFilters = filters[false].DefaultIfEmpty().Aggregate(Expression.AndAlso);
if (!query.RetrieveAllFields)
{
query = new Query(query.Fields.Concat(unsupportedFilters.GetFields().Select(u => u.FieldName)).Distinct(), supportedFilter, query.OrderByExpressions, query.Count);
}
if (unsupportedFilters != null)
{
context.Logger.Warning($"Data source {functionName} {this.alias} has unsupported filter {unsupportedFilters}. This could impact performance.");
}
}
// ReSharper disable once SuspiciousTypeConversion.Global, implemented in other assemblies.
var orderBySupport = this.dataSource as IDataSourceOrderBySupport;
if (orderBySupport != null && !orderBySupport.SupportsOrderBy(query.OrderByExpressions))
{
unsupportedOrderByExpressions = query.OrderByExpressions.ToArray();
if (!query.RetrieveAllFields)
{
query = new Query(query.Fields.Concat(unsupportedOrderByExpressions.SelectMany(e => e.Expression.GetFields().Select(f => f.FieldName))).Distinct(), query.FilterExpression, null, query.Count);
}
context.Logger.Warning($"Data source {functionName} {this.alias} has unsupported ORDER BY {string.Join(", ", unsupportedOrderByExpressions.Select(u => u.Expression + " " + (u.Ascending ? "ASC" : "DESC")))}. This could impact performance.");
}
var sourceName = functionName + (query.FilterExpression == null ? string.Empty : $" with query '{query.FilterExpression}'");
context.Logger.Verbose($"Retrieving data from {sourceName}.");
try
{
var result = this.dataSource.GetRows(context, new RowBuilder(this.alias), query).AfterLastElement(count => context.Logger.Verbose($"Retrieved {count} items from {sourceName}."));
if (unsupportedFilters != null)
{
result = result.Where(unsupportedFilters.GetRowFilter());
}
if (unsupportedOrderByExpressions != null)
{
result.OrderBy(unsupportedOrderByExpressions);
}
return(result);
}
catch (Exception e)
{
context.Logger.Error($"An error occurred while querying {sourceName}: {e.Message}.");
return(context.CreateEmptyAsyncEnumerable <Row>());
}
}
