public void Test_FdbQueryTransformExpression()
{
var expr = FdbQueryExpressions.Transform(
FdbQueryExpressions.RangeStartsWith(TuPack.EncodeKey("Hello", "World")),
(kvp) => kvp.Value.ToUnicode()
);
Log(expr);
Assert.That(expr, Is.Not.Null);
Assert.That(expr.Source, Is.Not.Null.And.InstanceOf <FdbQueryRangeExpression>());
Assert.That(expr.Transform, Is.Not.Null);
Assert.That(expr.Type, Is.EqualTo(typeof(IAsyncEnumerable <string>)));
Assert.That(expr.ElementType, Is.EqualTo(typeof(string)));
Log(FdbQueryExpressions.ExplainSequence(expr));
}
/// <summary>Projects each element of a sequence query into a new form.</summary>
public static IFdbAsyncSequenceQueryable <R> Select <T, R>(this IFdbAsyncSequenceQueryable <T> query, Expression <Func <T, R> > selector)
{
if (query == null)
{
throw new ArgumentNullException(nameof(query));
}
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
var sourceExpr = query.Expression as FdbQuerySequenceExpression <T>;
if (sourceExpr == null)
{
throw new ArgumentException("query");
}
var expr = FdbQueryExpressions.Transform(sourceExpr, selector);
return(query.Provider.CreateSequenceQuery <R>(expr));
}