/// <summary>
/// Returns a CqlQuery which after execution returns filtered sequence of values based on a predicate.
/// To execute this CqlQuery use <c>Execute()</c> method.
/// </summary>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
/// <param name="source">The CqlQuery<TSource> to filter.</param>
/// <param name="predicate">A function to test each element for a condition.</param>
/// <returns>a CqlQuery<TSource> which after execution will return an IEnumerable<TSource>
/// that contains elements from the input sequence that satisfy the condition.</returns>
public static CqlQuery <TSource> Where <TSource>(this CqlQuery <TSource> source, Expression <Func <TSource, bool> > predicate)
{
var ret = (CqlQuery <TSource>)source.Table.CreateQuery <TSource>(Expression.Call(
null, CqlMthHelps.WhereMi,
new[] { source.Expression, predicate }));
source.CopyQueryPropertiesTo(ret);
return(ret);
}
/// <summary>
/// Sorts the elements, which are returned from CqlQuery, in ascending order according to a key.
/// </summary>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
/// <typeparam name="TKey">The type of the key returned by keySelector.</typeparam>
/// <param name="source">A sequence of values to order, returned from CqlQuery<TSource>.</param>
/// <param name="keySelector">A function to extract a key from an element.</param>
/// <returns>a CqlQuery<TSource> which after execution returns an IEnumerable<TSource> sorted in ascending manner according to a key.</returns>
public static CqlQuery <TSource> OrderBy <TSource, TKey>(this CqlQuery <TSource> source, Expression <Func <TSource, TKey> > keySelector)
{
var ret = (CqlQuery <TSource>)source.Table.CreateQuery <TSource>(Expression.Call(
null, CqlMthHelps.OrderByMi,
new[] { source.Expression, keySelector }));
source.CopyQueryPropertiesTo(ret);
return(ret);
}
/// <summary>
/// Sorts the elements, which are returned from CqlQuery, in descending order according to a key.
/// </summary>
public static CqlQuery <TSource> ThenByDescending <TSource, TKey>(this CqlQuery <TSource> source, Expression <Func <TSource, TKey> > func)
{
var ret = (CqlQuery <TSource>)source.Table.CreateQuery <TSource>(Expression.Call(
null, CqlMthHelps.ThenByDescendingMi,
new[] { source.Expression, func }));
source.CopyQueryPropertiesTo(ret);
return(ret);
}
/// <summary>
/// The ALLOW FILTERING option allows to explicitly allow queries that require filtering.
/// Please note that a query using ALLOW FILTERING may thus have unpredictable performance (for the definition above), i.e. even a query that selects a handful of records may exhibit performance that depends on the total amount of data stored in the cluster.
/// </summary>
public static CqlQuery <TSource> AllowFiltering <TSource>(this CqlQuery <TSource> source)
{
var ret = (CqlQuery <TSource>)source.Table.CreateQuery <TSource>(Expression.Call(
null, CqlMthHelps.AllowFilteringMi,
new[] { source.Expression }));
source.CopyQueryPropertiesTo(ret);
return(ret);
}
/// <summary>
/// Returns a CqlQuery which after execution will return IEnumerable<TSource>
/// with specified number of contiguous elements from the start of a sequence.
/// To execute this CqlQuery use <c>Execute()</c> method.
/// </summary>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
/// <param name="source">The CqlQuery<TSource> to return the first element of.</param>
/// <param name="count">The number of elements to return.</param>
/// <returns>a CqlQuery<TSource> which after execution will return IEnumerable<TSource>
/// with specified number of contiguous elements from the start of a sequence.</returns>
public static CqlQuery <TSource> Take <TSource>(this CqlQuery <TSource> source, int count)
{
var ret = (CqlQuery <TSource>)source.Table.CreateQuery <TSource>(Expression.Call(
null, CqlMthHelps.TakeMi,
new[] { source.Expression, Expression.Constant(count) }));
source.CopyQueryPropertiesTo(ret);
return(ret);
}
/// <summary>
/// Returns a representation of a UPDATE ... IF ... cql statement, for Lightweight Transactions support
/// </summary>
public static CqlConditionalCommand <TSource> UpdateIf <TSource>(this CqlQuery <TSource> source, Expression <Func <TSource, bool> > predicate)
{
var update = new CqlUpdate(Expression.Call(
null, CqlMthHelps.UpdateIfMi,
new[] { source.Expression, predicate }), source.Table, source.StatementFactory, source.PocoData, source.MapperFactory);
source.CopyQueryPropertiesTo(update);
return(new CqlConditionalCommand <TSource>(update, source.MapperFactory));
}
/// <summary>
/// Returns a CqlQuery which after execution will return the first element of a sequence,
/// or a default value if the sequence contains no elements.
/// To execute this CqlQuery use <c>Execute()</c> method.
/// </summary>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
/// <param name="source">The CqlQuery<TSource> to return the first element of.</param>
/// <returns><c>a CqlQuery<TSource> which after execution will return default(TSource)</c> if source is empty,
/// otherwise the first element in source.</returns>
public static CqlQuerySingleElement <TSource> FirstOrDefault <TSource>(this CqlQuery <TSource> source)
{
var ret = new CqlQuerySingleElement <TSource>(source.Table.CreateQuery <TSource>(Expression.Call(
null, CqlMthHelps.FirstOrDefaultMi,
new[] { source.Expression, Expression.Constant(1) })).Expression, source);
source.CopyQueryPropertiesTo(ret);
return(ret);
}
/// <summary>
/// Returns a CqlQuery which after execution returns grouped sequence of values based on a predicate.
/// To execute this CqlQuery use <c>Execute()</c> method.
/// </summary>
/// <typeparam name="TSource">The type of the elements of source.</typeparam>
/// <typeparam name="TKey">The type of the value returned by selector.</typeparam>
/// <param name="source">The CqlQuery<TSource> to filter.</param>
/// <param name="predicate">A function to test each element for a condition.</param>
/// <returns>a CqlQuery<TSource> which after execution will return an IEnumerable<TSource>
/// that contains elements from the input sequence that satisfy the condition.</returns>
public static CqlQuery <IGrouping <TKey, TSource> > GroupBy <TKey, TSource>(this CqlQuery <TSource> source,
Expression <Func <TSource, TKey> > predicate)
{
if (source == null)
{
throw new ArgumentNullException("source");
}
if (predicate == null)
{
throw new ArgumentNullException("predicate");
}
var result = (CqlQuery <IGrouping <TKey, TSource> >)source.Table.CreateQuery <IGrouping <TKey, TSource> >(Expression.Call(
null, CqlMthHelps.GroupByMi,
new[] { source.Expression, predicate }));
source.CopyQueryPropertiesTo(result);
return(result);
}
