Fixed expand of single entity with no target

Author: hylkevds

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Development version 2.6.0
 
 **New Features**
+* Fixed expand of single entity with no target returning an object.
 * When using the Projects Plugin, generated Features now get the same restricted status and Projects as the Location they are generated from.
 
 **Internal changes & Bugfixes**

FROST-Server.SQLjooq/src/main/java/de/fraunhofer/iosb/ilt/frostserver/persistence/pgjooq/QueryBuilder.java

@@ -422,9 +422,8 @@ private void handleEntityExpand(QueryState sqlState, Expand expand, NavigationPr
         Query subQuery = expand.getSubQuery();
         TableRef tableRef = sqlState.getTableRef();
         TableRef joinRef = tableRef.createJoin(navPropEntity.getName(), queryState);
-        tableRef.addJoin(navPropEntity, joinRef);
         StaMainTable<?> joinedTable = joinRef.getTable();
-        QueryState subState = new QueryState(joinedTable, sqlState, sqlState.getNextAlias());
+        QueryState subState = new QueryState(joinedTable, joinRef, sqlState, sqlState.getCurrentAlias());
         Set<Property> subProperties = findSelectedProperties(subQuery);
         subState.setSelectedProperties(joinedTable.getPropertyFieldRegistry().getFieldsForProperties(subProperties));
         sqlState.addChildState(navPropEntity, subState);

FROST-Server.SQLjooq/src/main/java/de/fraunhofer/iosb/ilt/frostserver/persistence/pgjooq/relations/RelationOneToMany.java

@@ -121,7 +121,8 @@ public TableRef join(S joinSource, QueryState<?> queryState, TableRef sourceRef)
         Map<Field, Field> joinEquals = new HashMap<>();
         joinEquals.put(targetField, sourceField);
         return QueryBuilder.createJoinedRef(sourceRef, navProp, targetAliased)
-                .setJoinEquals(joinEquals);
+                .setJoinEquals(joinEquals)
+                .setJoinedOnField(sourceField);
     }
 
     @Override

FROST-Server.SQLjooq/src/main/java/de/fraunhofer/iosb/ilt/frostserver/persistence/pgjooq/utils/QueryState.java

@@ -76,18 +76,28 @@ public class QueryState<T extends StaMainTable<T>> {
     private final TableRef tableRef;
 
     public QueryState(T table, QueryState parent, String staAlias) {
-        this(parent.getPersistenceManager(), table, null);
+        this(parent.getPersistenceManager(), table, new TableRef(table), null);
+        this.parent = parent;
+        this.staAlias = staAlias;
+    }
+
+    public QueryState(T table, TableRef tableRef, QueryState parent, String staAlias) {
+        this(parent.getPersistenceManager(), table, tableRef, null);
         this.parent = parent;
         this.staAlias = staAlias;
     }
 
     public QueryState(JooqPersistenceManager pm, T table, Set<PropertyFields<T>> sqlSelectFields) {
+        this(pm, table, new TableRef(table), sqlSelectFields);
+    }
+
+    public QueryState(JooqPersistenceManager pm, T table, TableRef tableRef, Set<PropertyFields<T>> sqlSelectFields) {
         this.persistenceManager = pm;
         this.selectedProperties = sqlSelectFields;
+        this.tableRef = tableRef;
         sqlFrom = table;
         mainTable = table;
         sqlMainPkFields = table.getPkFields();
-        tableRef = new TableRef(table);
         staAlias = ALIAS_ROOT;
     }
 
@@ -112,8 +122,11 @@ public Entity entityFromRecord(Record tuple, DataSize dataSize, Query staQuery)
                 NavigationProperty expandPath = expand.getPath();
                 if (expandPath instanceof NavigationPropertyEntity navPropEntity) {
                     QueryState childState = getChildState(navPropEntity);
-                    Entity subEntity = childState.entityFromRecord(tuple, dataSize, expand.getSubQuery());
-                    mainEntity.setProperty(navPropEntity, subEntity);
+                    if (tuple.get(childState.getTableRef().getJoinedOnField()) != null) {
+                        // This navlink has a target.
+                        Entity subEntity = childState.entityFromRecord(tuple, dataSize, expand.getSubQuery());
+                        mainEntity.setProperty(navPropEntity, subEntity);
+                    }
                 }
             }
         }
@@ -135,6 +148,13 @@ public QueryState findStateForAlias(String alias) {
         return parent.findStateForAlias(alias);
     }
 
+    public String getCurrentAlias() {
+        if (parent == null) {
+            return ALIAS_PREFIX + aliasNr;
+        }
+        return parent.getCurrentAlias();
+    }
+
     public String getNextAlias() {
         if (parent == null) {
             return ALIAS_PREFIX + (++aliasNr);

FROST-Server.SQLjooq/src/main/java/de/fraunhofer/iosb/ilt/frostserver/persistence/pgjooq/utils/TableRef.java

@@ -34,6 +34,7 @@ public class TableRef {
     private final StaMainTable<?> table;
     private final Map<NavigationProperty, TableRef> joins = new HashMap<>();
     private Map<Field, Field> joinEquals;
+    private Field<?> joinedOnField;
 
     public TableRef(StaMainTable<?> table) {
         this.type = table.getEntityType();
@@ -94,4 +95,13 @@ public Field getJoinEqual(Field requested) {
         return found;
     }
 
+    public Field<?> getJoinedOnField() {
+        return joinedOnField;
+    }
+
+    public TableRef setJoinedOnField(Field<?> joinedOnField) {
+        this.joinedOnField = joinedOnField;
+        return this;
+    }
+
 }