using
System;
using
System.Linq;
using
System.Linq.Expressions;
using
Abp.Application.Services.Dto;
namespace
Abp.Linq.Extensions
{
/// <summary>
/// Some useful extension methods for <see cref="IQueryable{T}"/>.
/// </summary>
public
static
class
QueryableExtensions
{
/// <summary>
/// Used for paging. Can be used as an alternative to Skip(...).Take(...) chaining.
/// </summary>
public
static
IQueryable<T> PageBy<T>(
this
IQueryable<T> query,
int
skipCount,
int
maxResultCount)
{
if
(query ==
null
)
{
throw
new
ArgumentNullException(
"query"
);
}
return
query.Skip(skipCount).Take(maxResultCount);
}
/// <summary>
/// Used for paging with an <see cref="IPagedResultRequest"/> object.
/// </summary>
/// <param name="query">Queryable to apply paging</param>
/// <param name="pagedResultRequest">An object implements <see cref="IPagedResultRequest"/> interface</param>
public
static
IQueryable<T> PageBy<T>(
this
IQueryable<T> query, IPagedResultRequest pagedResultRequest)
{
return
query.PageBy(pagedResultRequest.SkipCount, pagedResultRequest.MaxResultCount);
}
/// <summary>
/// Filters a <see cref="IQueryable{T}"/> by given predicate if given condition is true.
/// </summary>
/// <param name="query">Queryable to apply filtering</param>
/// <param name="condition">A boolean value</param>
/// <param name="predicate">Predicate to filter the query</param>
/// <returns>Filtered or not filtered query based on <paramref name="condition"/></returns>
public
static
IQueryable<T> WhereIf<T>(
this
IQueryable<T> query,
bool
condition, Expression<Func<T,
bool
>> predicate)
{
return
condition
? query.Where(predicate)
: query;
}
/// <summary>
/// Filters a <see cref="IQueryable{T}"/> by given predicate if given condition is true.
/// </summary>
/// <param name="query">Queryable to apply filtering</param>
/// <param name="condition">A boolean value</param>
/// <param name="predicate">Predicate to filter the query</param>
/// <returns>Filtered or not filtered query based on <paramref name="condition"/></returns>
public
static
IQueryable<T> WhereIf<T>(
this
IQueryable<T> query,
bool
condition, Expression<Func<T,
int
,
bool
>> predicate)
{
return
condition
? query.Where(predicate)
: query;
}
}
}
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