/// <summary>
/// Executes the given <paramref name="queryModel" /> as a collection query, i.e. as a query returning objects of type
/// <typeparamref name="T" />.
/// The query does not end with a scalar result operator, but it can end with a single result operator, for example
/// <see cref="T:Remotion.Linq.Clauses.ResultOperators.SingleResultOperator" /> or
/// <see cref="T:Remotion.Linq.Clauses.ResultOperators.FirstResultOperator" />. In such a case, the returned enumerable
/// must yield exactly
/// one object (or none if the last result operator allows empty result sets).
/// </summary>
/// <typeparam name="T">The type of the items returned by the query.</typeparam>
/// <typeparam name="TFSEntity"></typeparam>
/// <param name="queryModel">
/// The <see cref="T:Remotion.Linq.QueryModel" /> representing the query to be executed. Analyze this via an
/// <see cref="T:Remotion.Linq.IQueryModelVisitor" />.
/// </param>
/// <returns>A scalar value of type <typeparamref name="TFSEntity" /> that represents the query's result.</returns>
public IEnumerable <T> ExecuteCollection <T>(QueryModel queryModel)
{
var command = FSQueryModelVisitor.GenerateFSQuery(queryModel);
if (_command != null)
{
var whereClause = command.WhereClause.HasValue() && _command.WhereClause.HasValue()
? command.WhereClause + " AND " + _command.WhereClause
: command.WhereClause.HasValue()
? command.WhereClause
: _command.WhereClause.HasValue()
? _command.WhereClause
: string.Empty;
var orderBy = _command.OrderByClause.HasValue()
? string.Join(",", _command.OrderByClause, command.OrderByClause).Trim(',')
: command.OrderByClause;
command = new FSCommand(
whereClause: whereClause,
orderByClause: orderBy,
offset: command.Offset ?? _command.Offset,
limit: command.Limit ?? _command.Limit
);
}
var fsQuery = _rep.Get(command.WhereClause, command.OrderByClause, command.Offset, command.Limit);
var projection = FSProjectionVisitor <TFSEntity, T> .BuildProjector(queryModel.SelectClause.Selector);
return(fsQuery.Select(projection));
}
/// <summary>
/// Executes the given <paramref name="queryModel" /> as a scalar query, i.e. as a query returning a scalar value of
/// type <typeparamref name="T" />.
/// The query ends with a scalar result operator, for example a
/// <see cref="T:Remotion.Linq.Clauses.ResultOperators.CountResultOperator" /> or a
/// <see cref="T:Remotion.Linq.Clauses.ResultOperators.SumResultOperator" />.
/// </summary>
/// <typeparam name="T">The type of the scalar value returned by the query.</typeparam>
/// <param name="queryModel">
/// The <see cref="T:Remotion.Linq.QueryModel" /> representing the query to be executed. Analyze this via an
/// <see cref="T:Remotion.Linq.IQueryModelVisitor" />.
/// </param>
/// <returns>A scalar value of type <typeparamref name="T" /> that represents the query's result.</returns>
/// <remarks>
/// The difference between
/// <see cref="M:Remotion.Linq.IQueryExecutor.ExecuteSingle``1(Remotion.Linq.QueryModel,System.Boolean)" /> and
/// <see cref="M:Remotion.Linq.IQueryExecutor.ExecuteScalar``1(Remotion.Linq.QueryModel)" /> is in the kind of object
/// that is returned.
/// <see cref="M:Remotion.Linq.IQueryExecutor.ExecuteSingle``1(Remotion.Linq.QueryModel,System.Boolean)" /> is used
/// when a query that would otherwise return a collection result set should pick a single value from the
/// set, for example the first, last, minimum, maximum, or only value in the set.
/// <see cref="M:Remotion.Linq.IQueryExecutor.ExecuteScalar``1(Remotion.Linq.QueryModel)" /> is used when a value is
/// calculated or aggregated from all the values in the collection result set. This applies to, for example, item
/// counts, average calculations,
/// checks for the existence of a specific item, and so on.
/// </remarks>
T IQueryExecutor.ExecuteScalar <T>(QueryModel queryModel)
{
var command = FSQueryModelVisitor.GenerateFSQuery(queryModel);
if (_command != null)
{
var whereClause = command.WhereClause.HasValue() && _command.WhereClause.HasValue()
? command.WhereClause + " AND " + _command.WhereClause
: command.WhereClause.HasValue()
? command.WhereClause
: _command.WhereClause.HasValue()
? _command.WhereClause
: string.Empty;
if (command.IsCountQuery)
{
var count = _rep.Count(whereClause);
if (typeof(T) == typeof(int))
{
return((T)(object)count);
}
return(default(T));
}
if (command.IsLongCountQuery)
{
var count = _rep.Count(whereClause);
if (typeof(T) == typeof(long))
{
return((T)(object)(long)count);
}
return(default(T));
}
}
return(ExecuteCollection <T>(queryModel)
.Single());
}
public FSQueryableExpressionVisitor(FSQueryModelVisitor fSQueryModelVisitor, IQuerySource querySource)
{
_fSQueryModelVisitor = fSQueryModelVisitor;
_querySource = querySource;
}
