public void Test_FdbQueryFilterExpression()
{
var expr = FdbQueryExpressions.Filter(
FdbQueryExpressions.RangeStartsWith(TuPack.EncodeKey("Hello", "World")),
(kvp) => kvp.Value.ToInt32() % 2 == 0
);
Log(expr);
Assert.That(expr, Is.Not.Null);
Assert.That(expr.Source, Is.Not.Null.And.InstanceOf <FdbQueryRangeExpression>());
Assert.That(expr.Filter, Is.Not.Null);
Assert.That(expr.Type, Is.EqualTo(typeof(IAsyncEnumerable <KeyValuePair <Slice, Slice> >)));
Assert.That(expr.ElementType, Is.EqualTo(typeof(KeyValuePair <Slice, Slice>)));
Log(FdbQueryExpressions.ExplainSequence(expr));
}
/// <summary>Filters a sequence query of values based on a predicate.</summary>
public static IFdbAsyncSequenceQueryable <T> Where <T>(this IFdbAsyncSequenceQueryable <T> query, Expression <Func <T, bool> > predicate)
{
if (query == null)
{
throw new ArgumentNullException(nameof(query));
}
if (predicate == null)
{
throw new ArgumentNullException(nameof(predicate));
}
var sourceExpr = query.Expression as FdbQuerySequenceExpression <T>;
if (sourceExpr == null)
{
throw new ArgumentException("query");
}
var expr = FdbQueryExpressions.Filter(sourceExpr, predicate);
return(query.Provider.CreateSequenceQuery <T>(expr));
}