public ProjectionExpression UpdateSelect(ProjectionExpression projection, Expression selectExpression)
{
//get the lambda expression of the select method
var lambda = (LambdaExpression)selectExpression.StripQuotes();
//if the lambda, is the identity lamda, simply return
if (lambda.IsIdentityLambda())
return projection;
//map the source argument of the lambda expression to the existing projection
Map.Add(lambda.Parameters[0], projection.Projection);
//get the new projection
var newProjection = Visit(lambda.Body);
//check if projection is actually changed
if (newProjection == lambda.Body)
return projection;
//get used columns
IEnumerable<SelectorExpression> columns = new ColumnFinder().FindColumns(newProjection);
SelectStatementExpression select = projection.Select;
var newSelect = new SelectStatementExpression(typeof(IEnumerable<>).MakeGenericType(newProjection.Type),
new SelectClauseExpression(columns.ToArray(),
select.SelectClause.Distinct),
select.TableName,
select.WhereClause,
select.OrderBy,
select.Limit,
select.AllowFiltering);
return new ProjectionExpression(newSelect, newProjection, projection.Aggregator, false, projection.Consistency, projection.PageSize);
}
public ProjectionExpression BuildWhere(ProjectionExpression projection, Expression whereClause)
{
//get the lambda expression of the select method
var lambda = (LambdaExpression)whereClause.StripQuotes();
//map the source argument of the lambda expression to the existing projection (the projection is what the where clause queries)
Map.Add(lambda.Parameters[0], projection.Projection);
if (projection.Select.WhereClause != null)
_relations = new HashSet<RelationExpression>(projection.Select.WhereClause);
else
_relations = new HashSet<RelationExpression>();
//get the new projections
Expression expression = Visit(lambda.Body);
if (!expression.IsTrue())
throw new CqlLinqException("Where clause contains unsupported constructs");
var select = projection.Select;
var newSelectStmt = new SelectStatementExpression(select.Type,
select.SelectClause,
select.TableName,
_relations.ToArray(),
select.OrderBy,
select.Limit,
select.AllowFiltering);
return new ProjectionExpression(newSelectStmt, projection.Projection,
projection.Aggregator, projection.CanTrackChanges, projection.Consistency, projection.PageSize);
}
public ProjectionExpression UpdateOrder(ProjectionExpression projection, Expression keySelectExpression,
bool ascending)
{
//get the lambda expression of the select method
var lambda = (LambdaExpression)keySelectExpression.StripQuotes();
//map the source argument of the lambda expression to the existing projection
Map.Add(lambda.Parameters[0], projection.Projection);
//get the new projection
var key = Visit(lambda.Body);
//check if we are dealing with a column
if ((CqlExpressionType)key.NodeType != CqlExpressionType.IdentifierSelector)
throw new CqlLinqException("Select key in OrderBy does not map to table column");
//get a reference to the select clause
SelectStatementExpression select = projection.Select;
//add the ordering to the list of orderBy clauses
var ordering = new List<OrderingExpression>(select.OrderBy);
ordering.Add(new OrderingExpression((SelectorExpression)key,
ascending
? CqlExpressionType.OrderAscending
: CqlExpressionType.OrderDescending));
var newSelect = new SelectStatementExpression(select.Type,
select.SelectClause,
select.TableName,
select.WhereClause,
ordering,
select.Limit,
select.AllowFiltering);
return new ProjectionExpression(newSelect, projection.Projection,
projection.Aggregator, projection.CanTrackChanges, projection.Consistency, projection.PageSize);
}
public virtual Expression VisitProjection(ProjectionExpression node)
{
return base.VisitExtension(node);
}
