protected override Expression VisitJoin(JoinExpression join)
{
join = (JoinExpression)base.VisitJoin(join);
if (join.Join == JoinType.CrossJoin && this.currentWhere != null)
{
// try to figure out which parts of the current where expression can be used for a join condition
var declaredLeft = DeclaredAliasGatherer.Gather(join.Left);
var declaredRight = DeclaredAliasGatherer.Gather(join.Right);
var declared = new HashSet <TableAlias>(declaredLeft.Union(declaredRight));
var exprs = this.currentWhere.Split(ExpressionType.And, ExpressionType.AndAlso);
var good = exprs.Where(e => CanBeJoinCondition(e, declaredLeft, declaredRight, declared)).ToList();
if (good.Count > 0)
{
var condition = good.Join(ExpressionType.And);
join = this.UpdateJoin(join, JoinType.InnerJoin, join.Left, join.Right, condition);
var newWhere = exprs.Where(e => !good.Contains(e)).Join(ExpressionType.And);
this.currentWhere = newWhere;
}
}
return(join);
}
protected override Expression VisitJoin(JoinExpression join)
{
this.VisitJoinLeft(join.Left);
this.WriteLine(Indentation.Same);
switch (join.Join)
{
case JoinType.CrossJoin:
this.Write("CROSS JOIN ");
break;
case JoinType.InnerJoin:
this.Write("INNER JOIN ");
break;
case JoinType.CrossApply:
this.Write("CROSS APPLY ");
break;
case JoinType.OuterApply:
this.Write("OUTER APPLY ");
break;
case JoinType.LeftOuter:
case JoinType.SingletonLeftOuter:
this.Write("LEFT OUTER JOIN ");
break;
}
this.VisitJoinRight(join.Right);
if (join.Condition != null)
{
this.WriteLine(Indentation.Inner);
this.Write("ON ");
this.VisitPredicate(join.Condition);
this.Indent(Indentation.Outer);
}
return(join);
}
public override ProjectionExpression GetQueryExpression(MappingEntity entity)
{
var tables = this.mapping.GetTables(entity);
if (tables.Count <= 1)
{
return(base.GetQueryExpression(entity));
}
var aliases = new Dictionary <string, TableAlias>();
MappingTable rootTable = tables.Single(ta => !this.mapping.IsExtensionTable(ta));
var tex = new TableExpression(new TableAlias(), entity, this.mapping.GetTableName(rootTable));
aliases.Add(this.mapping.GetAlias(rootTable), tex.Alias);
Expression source = tex;
foreach (MappingTable table in tables.Where(t => this.mapping.IsExtensionTable(t)))
{
TableAlias joinedTableAlias = new TableAlias();
string extensionAlias = this.mapping.GetAlias(table);
aliases.Add(extensionAlias, joinedTableAlias);
List <string> keyColumns = this.mapping.GetExtensionKeyColumnNames(table).ToList();
List <MemberInfo> relatedMembers = this.mapping.GetExtensionRelatedMembers(table).ToList();
string relatedAlias = this.mapping.GetExtensionRelatedAlias(table);
TableAlias relatedTableAlias;
aliases.TryGetValue(relatedAlias, out relatedTableAlias);
TableExpression joinedTex = new TableExpression(joinedTableAlias, entity, this.mapping.GetTableName(table));
Expression cond = null;
for (int i = 0, n = keyColumns.Count; i < n; i++)
{
var memberType = TypeHelper.GetMemberType(relatedMembers[i]);
var colType = this.GetColumnType(entity, relatedMembers[i]);
var relatedColumn = new ColumnExpression(memberType, colType, relatedTableAlias, this.mapping.GetColumnName(entity, relatedMembers[i]), new ColumnAlias(""));
var joinedColumn = new ColumnExpression(memberType, colType, joinedTableAlias, keyColumns[i], new ColumnAlias(""));
var eq = joinedColumn.Equal(relatedColumn);
cond = (cond != null) ? cond.And(eq) : eq;
}
source = new JoinExpression(JoinType.SingletonLeftOuter, source, joinedTex, cond);
}
var columns = new List <ColumnDeclaration>();
this.GetColumns(entity, aliases, columns);
SelectExpression root = new SelectExpression(new TableAlias(), columns, source, null);
var existingAliases = aliases.Values.ToArray();
Expression projector = this.GetEntityExpression(root, entity);
var selectAlias = new TableAlias();
var pc = ColumnProjector.ProjectColumns(this.Translator.Linguist.Language, projector, null, selectAlias, root.Alias);
var proj = new ProjectionExpression(
new SelectExpression(selectAlias, pc.Columns, root, null),
pc.Projector
);
return((ProjectionExpression)this.Translator.Police.ApplyPolicy(proj, entity.ElementType));
}
protected override Expression VisitProjection(ProjectionExpression proj)
{
SelectExpression save = this.currentSelect;
this.currentSelect = proj.Select;
try
{
if (!this.isTopLevel)
{
if (this.CanJoinOnClient(this.currentSelect))
{
// make a query that combines all the constraints from the outer queries into a single select
SelectExpression newOuterSelect = (SelectExpression)QueryDuplicator.Duplicate(save);
// remap any references to the outer select to the new alias;
SelectExpression newInnerSelect = (SelectExpression)ColumnMapper.Map(proj.Select, newOuterSelect.Alias, save.Alias);
// add outer-join test
ProjectionExpression newInnerProjection = this.language.AddOuterJoinTest(new ProjectionExpression(newInnerSelect, proj.Projector));
newInnerSelect = newInnerProjection.Select;
Expression newProjector = newInnerProjection.Projector;
TableAlias newAlias = new TableAlias();
var pc = ColumnProjector.ProjectColumns(this.language, newProjector, null, newAlias, newOuterSelect.Alias, newInnerSelect.Alias);
JoinExpression join = new JoinExpression(JoinType.OuterApply, newOuterSelect, newInnerSelect, null);
SelectExpression joinedSelect = new SelectExpression(newAlias, pc.Columns, join, null, null, null, proj.IsSingleton, null, null, false);
// apply client-join treatment recursively
this.currentSelect = joinedSelect;
newProjector = this.Visit(pc.Projector);
// compute keys (this only works if join condition was a single column comparison)
List <Expression> outerKeys = new List <Expression>();
List <Expression> innerKeys = new List <Expression>();
if (this.GetEquiJoinKeyExpressions(newInnerSelect.Where, newOuterSelect.Alias, outerKeys, innerKeys))
{
// outerKey needs to refer to the outer-scope's alias
var outerKey = outerKeys.Select(k => ColumnMapper.Map(k, save.Alias, newOuterSelect.Alias));
// innerKey needs to refer to the new alias for the select with the new join
var innerKey = innerKeys.Select(k => ColumnMapper.Map(k, joinedSelect.Alias, ((ColumnExpression)k).TableAlias));
ProjectionExpression newProjection = new ProjectionExpression(joinedSelect, newProjector, proj.Aggregator);
return(new ClientJoinExpression(newProjection, outerKey, innerKey));
}
}
else
{
bool saveJoin = this.canJoinOnClient;
this.canJoinOnClient = false;
var result = base.VisitProjection(proj);
this.canJoinOnClient = saveJoin;
return(result);
}
}
else
{
this.isTopLevel = false;
}
return(base.VisitProjection(proj));
}
finally
{
this.currentSelect = save;
}
}