/// <summary>
/// Transforms the specification to a target type, using a selector expression.
/// </summary>
/// <returns>The transformed specification expression.</returns>
/// <param name="selector">A selector to specify how an instance of the transformed/target type may be used to get an instance of the originally-specified type.</param>
/// <typeparam name="TTarget">The target type.</typeparam>
public ISpecificationExpression <TTarget> To <TTarget>(Expression <Func <TTarget, TOrigin> > selector)
{
if (selector == null)
{
throw new ArgumentNullException(nameof(selector));
}
var newExpression = expressionTransformer.Transform(spec.GetExpression(), selector);
return(Spec.Expr(newExpression));
}
public Expression <Func <Ticket, bool> > GetExpression()
{
ISpecificationExpression <Ticket> output = Spec.Expr <Ticket>(x => true);
foreach (var labelName in labelNames)
{
var nameExpression = Spec.Expr <Ticket>(x => x.Labels.Any(l => l.Name == labelName));
output = output.And(nameExpression);
}
return(output.GetExpression());
}
/// <summary>
/// Filters a Linq queryable object using the predicate defined in a specification expression.
/// </summary>
/// <returns>A queryable object which is filtered by the specification predicate.</returns>
/// <param name="query">A Linq queryable object.</param>
/// <param name="specification">A specification expression.</param>
/// <typeparam name="T">The generic type of the query and the specification.</typeparam>
public static IQueryable <T> Where <T>(this IQueryable <T> query, ISpecificationExpression <T> specification)
{
if (query == null)
{
throw new ArgumentNullException(nameof(query));
}
if (specification == null)
{
throw new ArgumentNullException(nameof(specification));
}
return(query.Where(specification.GetExpression()));
}
internal static Expression <Func <T, bool> > GetExpressionOrThrow <T>(this ISpecificationExpression <T> spec)
{
if (spec == null)
{
throw new ArgumentNullException(nameof(spec));
}
var expr = spec.GetExpression();
if (expr == null)
{
throw new ArgumentException($"{nameof(ISpecificationExpression<T>)}<T>.{nameof(ISpecificationExpression<T>.GetExpression)}() must not return null.", nameof(spec));
}
return(expr);
}