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Fix field projection collapsing nested JsonPointers to leaf names #183

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Merged
vharseko merged 1 commit into from
Jun 10, 2026
Merged

Fix field projection collapsing nested JsonPointers to leaf names #183

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26 changes: 19 additions & 7 deletions commons/rest/json-resource/src/main/java/org/forgerock/json/resource/Resources.java
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
* information: "Portions copyright [year] [name of copyright owner]".
*
* Copyright 2012-2016 ForgeRock AS.
* Portions copyright 2020-2026 3A Systems, LLC
*/

package org.forgerock.json.resource;
Expand All @@ -28,7 +29,6 @@
import java.lang.reflect.Method;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Map;

import org.forgerock.api.annotations.CollectionProvider;
import org.forgerock.api.annotations.Path;
Expand Down Expand Up @@ -99,6 +99,15 @@ public static RequestHandler asRequestHandler(final SynchronousRequestHandler sy
* <b>NOTE:</b> this method only performs a shallow copy of extracted
* fields, so changes to the filtered JSON value may impact the original
* JSON value, and vice-versa.
* <p>
* The projection preserves the nested structure of the requested fields:
* each requested {@link JsonPointer} is written back under its full path
* rather than being collapsed to its leaf name. As a result, leaf fields
* that share the same name at different levels of nesting do not conflict.
* For example, projecting {@code userName} and {@code manager/userName}
* over <code>{ "userName": "bjensen", "manager": { "userName": "jdoe" } }</code>
* yields <code>{ "userName": "bjensen", "manager": { "userName": "jdoe" } }</code>,
* i.e. the top-level {@code userName} is not overwritten by the nested one.
*
* @param resource
* The JSON value whose fields are to be filtered.
Expand All @@ -111,21 +120,24 @@ public static JsonValue filterResource(final JsonValue resource,
if (fields.isEmpty() || resource.isNull() || resource.size() == 0) {
return resource;
} else {
final Map<String, Object> filtered = new LinkedHashMap<>(fields.size());
final JsonValue filtered = new JsonValue(new LinkedHashMap<String, Object>(fields.size()));
for (final JsonPointer field : fields) {
if (field.isEmpty()) {
// Special case - copy resource fields (assumes Map).
filtered.putAll(resource.asMap());
filtered.asMap().putAll(resource.asMap());
} else {
// FIXME: what should we do if the field refers to an array element?
final JsonValue value = resource.get(field);
if (value != null) {
final String key = field.leaf();
filtered.put(key, value.getObject());
// Preserve the nested structure of the requested field
// instead of collapsing it to its leaf name. This keeps
// same-named leaf fields at different levels of nesting
// (e.g. "userName" and "manager/userName") from
// overwriting each other.
filtered.putPermissive(field, value.getObject());
}
}
}
return new JsonValue(filtered);
return filtered;
}
}

Expand Down
37 changes: 33 additions & 4 deletions commons/rest/json-resource/src/test/java/org/forgerock/json/resource/ResourcesTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
* information: "Portions copyright [year] [name of copyright owner]".
*
* Copyright 2012-2016 ForgeRock AS.
* Portions copyright 2020-2026 3A Systems, LLC
*/

package org.forgerock.json.resource;
Expand Down Expand Up @@ -161,25 +162,36 @@ public Object[][] testFilterData() {
{
filter("/a/b"),
content(object(field("a", object(field("b", "1"), field("c", "2"))), field("d", "3"))),
expected(object(field("b", "1")))
expected(object(field("a", object(field("b", "1")))))
},

{
filter("/a/b", "/d"),
content(object(field("a", object(field("b", "1"), field("c", "2"))), field("d", "3"))),
expected(object(field("b", "1"), field("d", "3")))
expected(object(field("a", object(field("b", "1"))), field("d", "3")))
},

{
filter("/a/b", "/a"),
content(object(field("a", object(field("b", "1"), field("c", "2"))), field("d", "3"))),
expected(object(field("b", "1"), field("a", object(field("b", "1"), field("c", "2")))))
expected(object(field("a", object(field("b", "1"), field("c", "2")))))
},

{
filter("/a", "/a/b"),
content(object(field("a", object(field("b", "1"), field("c", "2"))), field("d", "3"))),
expected(object(field("a", object(field("b", "1"), field("c", "2"))), field("b", "1")))
expected(object(field("a", object(field("b", "1"), field("c", "2")))))
},

// Same-named leaf fields at different levels of nesting must coexist
// (see OpenIDM discussion #183): the top-level "userName" must not be
// overwritten by the nested "manager/userName".
{
filter("/userName", "/manager", "/manager/userName"),
content(object(field("userName", "bjensen"),
field("manager", object(field("userName", "jdoe"))))),
expected(object(field("userName", "bjensen"),
field("manager", object(field("userName", "jdoe")))))
},

};
Expand All @@ -192,6 +204,23 @@ public void testFilter(List<JsonPointer> filter, JsonValue content, JsonValue ex
expected.getObject());
}

@Test
public void testFilterPreservesNestedFieldsWithCollidingLeafNames() {
// Given a resource with a "userName" both at the top level and nested
// inside "manager" (see OpenIDM discussion #183).
final JsonValue content = content(object(
field("userName", "bjensen"),
field("manager", object(field("userName", "jdoe")))));

// When projecting userName, manager and manager/userName.
final JsonValue result = Resources.filterResource(content,
filter("/userName", "/manager", "/manager/userName"));

// Then the nested structure is preserved and the leaf names do not collide.
assertThat(result.get("userName").asString()).isEqualTo("bjensen");
assertThat(result.get("manager").get("userName").asString()).isEqualTo("jdoe");
}

@DataProvider
public Object[][] testCollectionResourceProviderData() {
// @formatter:off
Expand Down
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