/**
* @return an empty String if there is no join clause, in other cases a String like the following
* is returned " as e left join e.bank as alias_1"
*/
public String getJoinClause() {
if (joinClause != null) {
return joinClause;
}
// make sure that the join clauses are computed
getWhereClause();
getOrderByClause();
if (getMainAlias() == null) {
return "";
}
final StringBuilder sb = new StringBuilder();
sb.append(" as " + getMainAlias() + " ");
for (JoinDefinition joinDefinition : joinDefinitions) {
sb.append(joinDefinition.getJoinStatement());
}
sb.append(" ");
joinClause = sb.toString();
return joinClause;
}
// Resolves the list of properties against existing join definitions
// creates new join definitions when necessary
private String resolveJoins(List<Property> props, String originalPath) {
String alias = getMainAlias();
if (alias == null) {
return originalPath;
}
int index = 0;
int joinedPropertyIndex = -1;
for (Property prop : props) {
boolean found = false;
for (JoinDefinition joinDefinition : joinDefinitions) {
if (joinDefinition.appliesTo(alias, prop)) {
alias = joinDefinition.getJoinAlias();
joinedPropertyIndex = index;
found = true;
break;
}
}
if (!found) {
// no more joins, leave
break;
}
index++;
}
// check if any new JoinDefinitions should be created
for (int i = (joinedPropertyIndex + 1); i < props.size(); i++) {
final Property prop = props.get(i);
if (prop.isPrimitive()) {
break;
}
// a joinable property
final JoinDefinition joinDefinition = new JoinDefinition();
joinDefinition.setOwnerAlias(alias);
joinDefinition.setJoinAlias(getNewUniqueAlias());
joinDefinition.setProperty(prop);
joinDefinitions.add(joinDefinition);
// move the result up to use the new JoinDefinition
alias = joinDefinition.getJoinAlias();
joinedPropertyIndex = i;
}
if (joinedPropertyIndex == (props.size() - 1)) {
return alias;
}
return alias + "." + props.get(props.size() - 1).getName();
}