public static IQueryable <TSubject> AutoFilter <TSubject, TPredicate>(
this IQueryable <TSubject> query,
TPredicate predicate,
Conventions.ComposeKind composeKind = Conventions.ComposeKind.And
)
where TSubject : class
=> Conventions <TSubject> .Filter(query, predicate, composeKind).OrderByConventions(predicate);
public static IQueryable <TSubject> Filter <TPredicate>(IQueryable <TSubject> query,
TPredicate predicate,
Conventions.ComposeKind composeKind = Conventions.ComposeKind.And)
{
var filterProps = FastTypeInfo <TPredicate>
.PublicProperties
.ToArray();
var filterPropNames = filterProps
.Select(x => x.Name)
.ToArray();
var modelType = typeof(TSubject);
var parameter = Expression.Parameter(modelType);
var props = FastTypeInfo <TSubject>
.PublicProperties
.Where(x => filterPropNames.Contains(x.Name))
.Select(x => new
{
Property = x,
Value = filterProps.Single(y => y.Name == x.Name).GetValue(predicate)
})
.Where(x => x.Value != null)
.Select(x =>
{
var property = Expression.Property(parameter, x.Property);
Expression value = Expression.Constant(x.Value);
value = Expression.Convert(value, property.Type);
var body = Conventions.Filters[property.Type](property, value);
return(Expression.Lambda <Func <TSubject, Boolean> >(body, parameter));
})
.ToArray();
if (!props.Any())
{
return(query);
}
var expr = composeKind == Conventions.ComposeKind.And
? props.Aggregate((c, n) => c.And(n))
: props.Aggregate((c, n) => c.Or(n));
return(query.Where(expr));
}
public static Expression <Func <TSubject, Boolean> > FilterExpression <TPredicate>(TPredicate predicate,
Conventions.ComposeKind composeKind = Conventions.ComposeKind.And
)
{
if (predicate == null)
{
throw new ArgumentNullException(nameof(predicate));
}
// ищем беспараметрический конструктор
var defaultPredicate = FastTypeInfo <TPredicate> .Constructors
.Any(c => c.GetParameters().Length == 0) ?
Activator.CreateInstance(typeof(TPredicate))
: null;
// ***сравнение значений полей
Boolean Equal(PropertyInfo pi, Object a, Object b)
{
if (a == null || b == null)
{
return(false);
}
var aVal = pi.GetValue(a);
var bVal = pi.GetValue(b);
return(aVal != null?aVal.Equals(bVal) : bVal != null ? false : true);
}
// *** end Equal
// фильтруем только по тем полям, значения которых отличны от дефолтных
var filterProps = FastTypeInfo <TPredicate>
.PublicProperties
.Where(x => !Equal(x, predicate, defaultPredicate))
.ToArray();
var filterPropNames = filterProps
.Select(x => x.Name)
.ToArray();
var modelType = typeof(TSubject);
var parameter = Expression.Parameter(modelType);
var props = FastTypeInfo <TSubject>
.PublicProperties
.Where(x => filterPropNames.Contains(x.Name))
.Select(x => new
{
Property = x,
Value = filterProps.Single(y => y.Name == x.Name).GetValue(predicate)
})
.Where(x => x.Value != null)
.Select(x =>
{
var property = Expression.Property(parameter, x.Property);
Expression value = Expression.Constant(x.Value);
value = Expression.Convert(value, property.Type);
var body = Conventions.Filters[property.Type](property, value);
return(Expression.Lambda <Func <TSubject, Boolean> >(body, parameter));
})
.ToArray();
if (!props.Any())
{
return(Expression.Lambda <Func <TSubject, Boolean> >(Expression.Constant(true), parameter));
}
var expr = composeKind == Conventions.ComposeKind.And
? props.Aggregate((c, n) => c.And(n))
: props.Aggregate((c, n) => c.Or(n));
return(expr);
}
