ClassQueryableExtensions
Holds extension methods for IQueryable.
Definition
Namespace:Telerik.Windows.Data
Assembly:Telerik.Windows.Data.dll
Syntax:
public static class QueryableExtensionsInheritance: objectQueryableExtensions
Methods
Aggregate(IQueryable, AggregateFunction)
Calculates the results of a given aggregate function on a sequence of elements.
Declaration
public static AggregateResultCollection Aggregate(this IQueryable source, AggregateFunction aggregateFunction)Parameters
source
An IQueryable whose elements will be used for aggregate calculation.
aggregateFunction
The aggregate function.
Returns
Collection of AggregateResults calculated for the function.
Aggregate(IQueryable, IEnumerable<AggregateFunction>)
Calculates the results of given aggregates functions on a sequence of elements.
Declaration
public static AggregateResultCollection Aggregate(this IQueryable source, IEnumerable<AggregateFunction> aggregateFunctions)Parameters
source
An IQueryable whose elements will be used for aggregate calculation.
aggregateFunctions
IEnumerable<AggregateFunction>
The aggregate functions.
Returns
Collection of AggregateResults calculated for each function.
Count(IQueryable)
Returns the number of elements in a sequence.
Declaration
public static int Count(this IQueryable source)Parameters
source
The IQueryable that contains the elements to be counted.
Returns
The number of elements in the input sequence.
Exceptions
source is null.
ElementAt(IQueryable, int)
Returns the element at a specified index in a sequence.
Declaration
public static object ElementAt(this IQueryable source, int index)Parameters
source
An IQueryable to return an element from.
index
The zero-based index of the element to retrieve.
Returns
The element at the specified position in source.
Exceptions
source is null.
index is less than zero.
Except(IQueryable, IQueryable)
Produces the set difference of two sequences by using the default equality comparer to compare values.
Declaration
public static IQueryable Except(this IQueryable source1, IQueryable source2)Parameters
source1
source2
Returns
First(IQueryable)
Returns the firsts item in a sequence.
Declaration
public static object First(this IQueryable source)Parameters
source
The IQueryable that contains the elements to be counted.
Returns
First element.
GroupBy(IQueryable, IEnumerable<IGroupDescriptor>)
Groups the elements of a sequence according to a specified groupDescriptors.
Declaration
public static IQueryable GroupBy(this IQueryable source, IEnumerable<IGroupDescriptor> groupDescriptors)Parameters
source
An IQueryable whose elements to group.
groupDescriptors
The group descriptors used for grouping.
Returns
An IQueryable with IGroup items, whose elements contains a sequence of objects and a key.
GroupBy(IQueryable, LambdaExpression)
Groups the elements of a sequence according to a specified key selector function.
Declaration
public static IQueryable GroupBy(this IQueryable source, LambdaExpression keySelector)Parameters
source
An IQueryable whose elements to group.
keySelector
A function to extract the key for each element.
Returns
An IQueryable with IGrouping<TKey, TElement> items, whose elements contains a sequence of objects and a key.
OrderBy(IQueryable, LambdaExpression)
Sorts the elements of a sequence in ascending order according to a key.
Declaration
public static IQueryable OrderBy(this IQueryable source, LambdaExpression keySelector)Parameters
source
A sequence of values to order.
keySelector
A function to extract a key from an element.
Returns
An IQueryable whose elements are sorted according to a key.
OrderBy(IQueryable, LambdaExpression, ListSortDirection?)
Calls OrderBy(IQueryable, LambdaExpression)
or OrderByDescending(IQueryable, LambdaExpression) depending on the sortDirection.
Declaration
public static IQueryable OrderBy(this IQueryable source, LambdaExpression keySelector, ListSortDirection? sortDirection)Parameters
source
The source.
keySelector
The key selector.
sortDirection
The sort direction.
Returns
An IQueryable whose elements are sorted according to a key.
OrderByDescending(IQueryable, LambdaExpression)
Sorts the elements of a sequence in descending order according to a key.
Declaration
public static IQueryable OrderByDescending(this IQueryable source, LambdaExpression keySelector)Parameters
source
A sequence of values to order.
keySelector
A function to extract a key from an element.
Returns
An IQueryable whose elements are sorted in descending order according to a key.
Page(IQueryable, int, int)
Pages through the elements of a sequence until the specified
pageIndex using pageSize.
Declaration
public static IQueryable Page(this IQueryable source, int pageIndex, int pageSize)Parameters
source
A sequence of values to page.
pageIndex
Index of the page.
pageSize
Size of the page.
Returns
An IQueryable whose elements are at the specified pageIndex.
Select(IQueryable, IEnumerable<ISelectDescriptor>)
Selects a sequence of objects based on a IEnumerable of SelectDescriptor.
Declaration
public static IQueryable Select(this IQueryable source, IEnumerable<ISelectDescriptor> selectDescriptors)Parameters
source
The source.
selectDescriptors
IEnumerable<ISelectDescriptor>
The select descriptor enumerable.
Returns
An IQueryable that contains elements from the input sequence
that will be projected according to the specified selectDescriptors.
Select(IQueryable, LambdaExpression)
Projects each element of a sequence into a new form.
Declaration
public static IQueryable Select(this IQueryable source, LambdaExpression selector)Parameters
source
A sequence of values to project.
selector
A projection function to apply to each element.
Returns
An IQueryable whose elements are the result of invoking a
projection selector on each element of source.
Select(IQueryable, SelectDescriptorCollection)
Selects a sequence of objects based on a SelectDescriptorCollection.
Declaration
public static IQueryable Select(this IQueryable source, SelectDescriptorCollection selectDescriptors)Parameters
source
The source.
selectDescriptors
The select descriptor collection.
Returns
An IQueryable that contains elements from the input sequence
that will be projected according to the specified selectDescriptors.
Skip(IQueryable, int)
Bypasses a specified number of elements in a sequence and then returns the remaining elements.
Declaration
public static IQueryable Skip(this IQueryable source, int count)Parameters
source
An IQueryable to return elements from.
count
The number of elements to skip before returning the remaining elements.
Returns
An IQueryable that contains elements that occur after the specified index in the input sequence.
Exceptions
source is null.
Sort(IQueryable, IEnumerable<ISortDescriptor>)
Sorts the elements of a sequence using the specified sort descriptors.
Declaration
public static IQueryable Sort(this IQueryable source, IEnumerable<ISortDescriptor> sortDescriptors)Parameters
source
A sequence of values to sort.
sortDescriptors
The sort descriptors used for sorting.
Returns
An IQueryable whose elements are sorted according to a sortDescriptors.
Sort(IQueryable, IEnumerable<SortDescriptor>)
Sorts the elements of a sequence using the specified sort descriptors.
Declaration
public static IQueryable Sort(this IQueryable source, IEnumerable<SortDescriptor> sortDescriptors)Parameters
source
A sequence of values to sort.
sortDescriptors
The sort descriptors used for sorting.
Returns
An IQueryable whose elements are sorted according to a sortDescriptors.
Sort(IQueryable, SortDescriptorCollection)
Sorts the elements of a sequence using the specified sort descriptors.
Declaration
public static IQueryable Sort(this IQueryable source, SortDescriptorCollection sortDescriptors)Parameters
source
A sequence of values to sort.
sortDescriptors
The sort descriptors used for sorting.
Returns
An IQueryable whose elements are sorted according to a sortDescriptors.
Take(IQueryable, int)
Returns a specified number of contiguous elements from the start of a sequence.
Declaration
public static IQueryable Take(this IQueryable source, int count)Parameters
source
The sequence to return elements from.
count
The number of elements to return.
Returns
An IQueryable that contains the specified number
of elements from the start of source.
Exceptions
source is null.
ToIList(IQueryable)
Creates a IList<T> from an IQueryable where T is ElementType.
Declaration
public static IList ToIList(this IQueryable source)Parameters
source
The IQueryable to create a List<T> from.
Returns
A List<T> that contains elements from the input sequence.
Exceptions
source is null.
ToIList<T>(IQueryable<T>)
Creates a IList<T> from an IQueryable where T is ElementType.
Declaration
public static IList<T> ToIList<T>(this IQueryable<T> source)Parameters
source
IQueryable<T>
The IQueryable to create a List<T> from.
Returns
IList<T>
A List<T> that contains elements from the input sequence.
Exceptions
source is null.
Union(IQueryable, IQueryable)
Produces the set union of two sequences by using the default equality comparer.
Declaration
public static IQueryable Union(this IQueryable source1, IQueryable source2)Parameters
source1
source2
Returns
Where(IQueryable, CompositeFilterDescriptorCollection)
Filters a sequence of values based on a CompositeFilterDescriptorCollection.
Declaration
public static IQueryable Where(this IQueryable source, CompositeFilterDescriptorCollection filterDescriptors)Parameters
source
The source.
filterDescriptors
CompositeFilterDescriptorCollection
The composite filter descriptor collection.
Returns
An IQueryable that contains elements from the input sequence
that satisfy the conditions specified by the filterDescriptors.
Where(IQueryable, Expression)
Filters a sequence of values based on a predicate.
Declaration
public static IQueryable Where(this IQueryable source, Expression predicate)Parameters
source
An IQueryable to filter.
predicate
A function to test each element for a condition.
Returns
An IQueryable that contains elements from the input sequence
that satisfy the condition specified by predicate.
Where(IQueryable, FilterDescriptorCollection)
Filters a sequence of values based on a collection of IFilterDescriptor.
Declaration
public static IQueryable Where(this IQueryable source, FilterDescriptorCollection filterDescriptors)Parameters
source
The source.
filterDescriptors
The filter descriptors.
Returns
An IQueryable that contains elements from the input sequence
that satisfy the conditions specified by each filter descriptor in filterDescriptors.
Where(IQueryable, IEnumerable<IFilterDescriptor>)
Filters a sequence of values based on a collection of IFilterDescriptor.
Declaration
public static IQueryable Where(this IQueryable source, IEnumerable<IFilterDescriptor> filterDescriptors)Parameters
source
The source.
filterDescriptors
IEnumerable<IFilterDescriptor>
The filter descriptors.
Returns
An IQueryable that contains elements from the input sequence
that satisfy the conditions specified by each filter descriptor in filterDescriptors.