keycloak · thomasdarimont · Jul 13, 2025
@@ -5,9 +5,11 @@
 
 import com.fasterxml.jackson.annotation.JsonAnyGetter;
 import com.fasterxml.jackson.annotation.JsonAnySetter;
+import com.fasterxml.jackson.annotation.JsonFilter;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.fasterxml.jackson.annotation.JsonInclude;
 
+@JsonFilter("projection")
 @JsonInclude(JsonInclude.Include.NON_ABSENT)
 public class BaseRepresentation {
 

@@ -0,0 +1,20 @@
+package org.keycloak.quarkus.runtime.integration.jaxrs;
+
+import jakarta.ws.rs.container.ContainerRequestContext;
+import jakarta.ws.rs.container.ContainerRequestFilter;
+import jakarta.ws.rs.container.PreMatching;
+import jakarta.ws.rs.ext.Provider;
+import org.keycloak.services.util.Projections;
+
+@Provider
+@PreMatching
+public class ProjectionsPreFilter implements ContainerRequestFilter {
+
+    @Override
+    public void filter(ContainerRequestContext requestContext) {
+        String projectionsParam = requestContext.getUriInfo().getQueryParameters().getFirst(Projections.PARAM);
+        if (projectionsParam != null) {
+            Projections.setCurrent(requestContext, projectionsParam);
+        }
+    }
+}
@@ -3,7 +3,6 @@
 import java.util.stream.Stream;
 
 import jakarta.validation.Valid;
-import jakarta.validation.groups.ConvertGroup;
 import jakarta.ws.rs.QueryParam;
 import org.eclipse.microprofile.openapi.annotations.Operation;
 import org.eclipse.microprofile.openapi.annotations.extensions.Extension;
@@ -19,8 +18,8 @@
 import jakarta.ws.rs.PathParam;
 import jakarta.ws.rs.Produces;
 import jakarta.ws.rs.core.MediaType;
-import org.keycloak.representations.admin.v2.validation.CreateClient;
 import org.keycloak.services.resources.KeycloakOpenAPI;
+import org.keycloak.services.util.Projections;
 
 @Tag(name = KeycloakOpenAPI.Admin.Tags.CLIENTS_V2)
 @Extension(name = KeycloakOpenAPI.Profiles.ADMIN, value = "")
@@ -40,6 +39,6 @@ ClientRepresentation createClient(@Valid ClientRepresentation client,
                                       @QueryParam("fieldValidation") FieldValidation fieldValidation);
 
     @Path("{id}")
-    ClientApi client(@PathParam("id") String id);
+    ClientApi client(@PathParam("id") String id, @QueryParam(Projections.PARAM) Projections projections);
 }
 
@@ -20,6 +20,7 @@
 import jakarta.ws.rs.WebApplicationException;
 import jakarta.ws.rs.core.Response;
 import org.keycloak.validation.jakarta.JakartaValidatorProvider;
+import org.keycloak.services.util.Projections;
 
 public class DefaultClientsApi implements ClientsApi {
     private final KeycloakSession session;
@@ -53,7 +54,7 @@ public ClientRepresentation createClient(@Valid ClientRepresentation client, Fie
     }
 
     @Override
-    public ClientApi client(@PathParam("id") String clientId) {
+    public ClientApi client(@PathParam("id") String clientId, @QueryParam("fields") Projections projections) {
         var client = Optional.ofNullable(session.clients().getClientByClientId(realm, clientId)).orElseThrow(() -> new NotFoundException("Client cannot be found"));
         session.getContext().setClient(client);
         return session.getProvider(ClientApi.class);

@@ -22,11 +22,16 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
 import com.fasterxml.jackson.databind.module.SimpleModule;
+import com.fasterxml.jackson.databind.ser.FilterProvider;
+import com.fasterxml.jackson.databind.ser.PropertyWriter;
+import com.fasterxml.jackson.databind.ser.impl.SimpleBeanPropertyFilter;
+import com.fasterxml.jackson.databind.ser.impl.SimpleFilterProvider;
 import com.fasterxml.jackson.databind.type.TypeFactory;
 import com.fasterxml.jackson.datatype.jdk8.StreamSerializer;
 
 import jakarta.ws.rs.ext.ContextResolver;
 import jakarta.ws.rs.ext.Provider;
+
 import java.util.stream.Stream;
 
 /**
@@ -62,6 +67,12 @@ public static ObjectMapper createStreamSerializer() {
             mapper.findAndRegisterModules();
         }
 
+        if (Boolean.parseBoolean(System.getProperty("keycloak.jsonEnableProjections", "true"))) {
+            // used via @JsonFilter in BaseRepresentation
+            FilterProvider filters = new SimpleFilterProvider().addFilter("projection", new FieldProjectionFilter());
+            mapper.setFilterProvider(filters);
+        }
+
         return mapper;
     }
 
@@ -74,4 +85,17 @@ private static class ObjectMapperInitializer {
 
         private static final ObjectMapper OBJECT_MAPPER = createStreamSerializer();
     }
+
+    private static class FieldProjectionFilter extends SimpleBeanPropertyFilter {
+
+        protected boolean include(PropertyWriter writer) {
+
+            Projections projections = Projections.getCurrent();
+            if (projections == null) {
+                return super.include(writer);
+            }
+
+            return projections.contains(writer.getName());
+        }
+    }
 }
@@ -0,0 +1,56 @@
+package org.keycloak.services.util;
+
+import jakarta.ws.rs.container.ContainerRequestContext;
+import org.jboss.resteasy.reactive.server.core.CurrentRequestManager;
+import org.jboss.resteasy.reactive.server.core.ResteasyReactiveRequestContext;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.regex.Pattern;
+
+public class Projections {
+
+    public static final String PARAM = "fields";
+
+    private static final String REQUEST_PROPERTY = "projections";
+
+    private static final Pattern COMMA = Pattern.compile(",");
+
+    private static final Set<String> INCLUDE_ALL = Collections.unmodifiableSet(new HashSet<>());
+
+    private final Set<String> fields;
+
+    public Projections(String raw) {
+        this.fields = raw == null ? INCLUDE_ALL : Set.of(COMMA.split(raw));
+    }
+
+    public Set<String> getFields() {
+        return fields;
+    }
+
+    @Override
+    public String toString() {
+        return fields.toString();
+    }
+
+    public boolean contains(String attr) {
+        if (fields == INCLUDE_ALL) {
+            return true;
+        }
+        return fields.contains(attr);
+    }
+
+    public static Projections getCurrent() {
+        ResteasyReactiveRequestContext context = CurrentRequestManager.get();
+        if (context == null) {
+            return null;
+        }
+        return (Projections) context.getProperty(Projections.REQUEST_PROPERTY);
+    }
+
+    public static void setCurrent(ContainerRequestContext requestContext, String projectionsParam) {
+        // TODO avoid duplicate parsing here and on resource method
+        requestContext.setProperty(Projections.REQUEST_PROPERTY, new Projections(projectionsParam));
+    }
+}