google · l46kok · Jan 23, 2026
diff --git a/bundle/src/test/java/dev/cel/bundle/BUILD.bazel b/bundle/src/test/java/dev/cel/bundle/BUILD.bazel
@@ -67,6 +67,7 @@ java_library(
         "@maven//:com_google_truth_extensions_truth_proto_extension",
         "@maven//:junit_junit",
         "@maven//:org_jspecify_jspecify",
+        "//testing/protos:single_file_java_proto",
     ],
 )
 

diff --git a/bundle/src/test/java/dev/cel/bundle/CelImplTest.java b/bundle/src/test/java/dev/cel/bundle/CelImplTest.java
@@ -112,6 +112,7 @@
 import dev.cel.runtime.CelUnknownSet;
 import dev.cel.runtime.CelVariableResolver;
 import dev.cel.runtime.UnknownContext;
+import dev.cel.testing.testdata.SingleFileProto.SingleFile;
 import dev.cel.testing.testdata.proto3.StandaloneGlobalEnum;
 import java.time.Instant;
 import java.util.ArrayList;
@@ -2193,6 +2194,24 @@ public void toBuilder_isImmutable() {
     assertThat(newRuntimeBuilder).isNotEqualTo(celImpl.toRuntimeBuilder());
   }
 
+  @Test
+  public void eval_withJsonFieldName()
+      throws Exception {
+    Cel cel =
+        standardCelBuilderWithMacros()
+            .addVar("file", StructTypeReference.create(SingleFile.getDescriptor().getFullName()))
+            .addMessageTypes(SingleFile.getDescriptor())
+            .setOptions(CelOptions.current().enableJsonFieldNames(true).build())
+            .build();
+    CelAbstractSyntaxTree ast =
+        cel.compile("file.camelCased").getAst();
+
+    Object result = cel.createProgram(ast).eval(ImmutableMap.of("file", SingleFile.newBuilder().setSnakeCased("foo").build()));
+
+    assertThat(result).isEqualTo("foo");
+  }
+
+
   private static TypeProvider aliasingProvider(ImmutableMap<String, Type> typeAliases) {
     return new TypeProvider() {
       @Override

diff --git a/checker/src/main/java/dev/cel/checker/CelCheckerLegacyImpl.java b/checker/src/main/java/dev/cel/checker/CelCheckerLegacyImpl.java
@@ -456,9 +456,13 @@ public CelCheckerLegacyImpl build() {
       }
 
       CelTypeProvider messageTypeProvider =
-          new ProtoMessageTypeProvider(
-              CelDescriptorUtil.getAllDescriptorsFromFileDescriptor(
-                  fileTypeSet, celOptions.resolveTypeDependencies()));
+          ProtoMessageTypeProvider.newBuilder()
+              .setAllowJsonFieldNames(celOptions.enableJsonFieldNames())
+              .setCelDescriptors(
+                  CelDescriptorUtil.getAllDescriptorsFromFileDescriptor(
+                      fileTypeSet, celOptions.resolveTypeDependencies()))
+              .build();
+
       if (celTypeProvider != null && fileTypeSet.isEmpty()) {
         messageTypeProvider = celTypeProvider;
       } else if (celTypeProvider != null) {

diff --git a/common/src/main/java/dev/cel/common/CelOptions.java b/common/src/main/java/dev/cel/common/CelOptions.java
@@ -83,6 +83,8 @@ public enum ProtoUnsetFieldOptions {
 
   public abstract boolean enableNamespacedDeclarations();
 
+  public abstract boolean enableJsonFieldNames();
+
   // Evaluation related options
 
   public abstract boolean disableCelStandardEquality();
@@ -150,6 +152,7 @@ public static Builder newBuilder() {
         .enableTimestampEpoch(false)
         .enableHeterogeneousNumericComparisons(false)
         .enableNamespacedDeclarations(true)
+        .enableJsonFieldNames(false)
         // Evaluation options
         .disableCelStandardEquality(true)
         .evaluateCanonicalTypesToNativeValues(false)
@@ -170,7 +173,8 @@ public static Builder newBuilder() {
         .enableStringConcatenation(true)
         .enableListConcatenation(true)
         .enableComprehension(true)
-        .maxRegexProgramSize(-1);
+        .maxRegexProgramSize(-1)
+        ;
   }
 
   /**
@@ -529,6 +533,12 @@ public abstract static class Builder {
      */
     public abstract Builder maxRegexProgramSize(int value);
 
+    /**
+     * TODO
+     */
+    public abstract Builder enableJsonFieldNames(boolean value);
+
+
     public abstract CelOptions build();
   }
 }
diff --git a/common/src/main/java/dev/cel/common/types/ProtoMessageTypeProvider.java b/common/src/main/java/dev/cel/common/types/ProtoMessageTypeProvider.java
@@ -14,11 +14,9 @@
 
 package dev.cel.common.types;
 
-import static com.google.common.collect.ImmutableList.toImmutableList;
 import static com.google.common.collect.ImmutableMap.toImmutableMap;
 
 import com.google.common.collect.ImmutableCollection;
-import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableMultimap;
 import com.google.common.collect.ImmutableSet;
@@ -34,11 +32,11 @@
 import dev.cel.common.CelDescriptorUtil;
 import dev.cel.common.CelDescriptors;
 import dev.cel.common.internal.FileDescriptorSetConverter;
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Optional;
-import java.util.function.Function;
 
 /**
  * The {@code ProtoMessageTypeProvider} implements the {@link CelTypeProvider} interface to provide
@@ -68,35 +66,35 @@ public final class ProtoMessageTypeProvider implements CelTypeProvider {
           .buildOrThrow();
 
   private final ImmutableMap<String, CelType> allTypes;
+  private final boolean allowJsonFieldNames;
 
+  /** Returns a new builder for {@link ProtoMessageTypeProvider}. */
+  public static Builder newBuilder() {
+    return new Builder();
+  }
+
+  @Deprecated
   public ProtoMessageTypeProvider() {
-    this(CelDescriptors.builder().build());
+    this(CelDescriptors.builder().build(), false);
   }
 
+  @Deprecated
   public ProtoMessageTypeProvider(FileDescriptorSet descriptorSet) {
     this(
         CelDescriptorUtil.getAllDescriptorsFromFileDescriptor(
-            FileDescriptorSetConverter.convert(descriptorSet)));
+            FileDescriptorSetConverter.convert(descriptorSet)), false);
   }
 
+  @Deprecated
   public ProtoMessageTypeProvider(Iterable<Descriptor> descriptors) {
     this(
         CelDescriptorUtil.getAllDescriptorsFromFileDescriptor(
-            ImmutableSet.copyOf(Iterables.transform(descriptors, Descriptor::getFile))));
+            ImmutableSet.copyOf(Iterables.transform(descriptors, Descriptor::getFile))), false);
   }
 
+  @Deprecated
   public ProtoMessageTypeProvider(ImmutableSet<FileDescriptor> fileDescriptors) {
-    this(CelDescriptorUtil.getAllDescriptorsFromFileDescriptor(fileDescriptors));
-  }
-
-  public ProtoMessageTypeProvider(CelDescriptors celDescriptors) {
-    this.allTypes =
-        ImmutableMap.<String, CelType>builder()
-            .putAll(createEnumTypes(celDescriptors.enumDescriptors()))
-            .putAll(
-                createProtoMessageTypes(
-                    celDescriptors.messageTypeDescriptors(), celDescriptors.extensionDescriptors()))
-            .buildOrThrow();
+    this(CelDescriptorUtil.getAllDescriptorsFromFileDescriptor(fileDescriptors), false);
   }
 
   @Override
@@ -120,8 +118,14 @@ private ImmutableMap<String, CelType> createProtoMessageTypes(
       if (protoMessageTypes.containsKey(descriptor.getFullName())) {
         continue;
       }
-      ImmutableList<String> fieldNames =
-          descriptor.getFields().stream().map(FieldDescriptor::getName).collect(toImmutableList());
+
+      ImmutableSet.Builder<String> fieldNamesBuilder = ImmutableSet.builder() ;
+      for (FieldDescriptor fd : descriptor.getFields()) {
+        fieldNamesBuilder.add(fd.getName());
+        if (allowJsonFieldNames) {
+          fieldNamesBuilder.add(fd.getJsonName());
+        }
+      }
 
       Map<String, FieldDescriptor> extensionFields = new HashMap<>();
       for (FieldDescriptor extension : extensionMap.get(descriptor.getFullName())) {
@@ -133,7 +137,7 @@ private ImmutableMap<String, CelType> createProtoMessageTypes(
           descriptor.getFullName(),
           ProtoMessageType.create(
               descriptor.getFullName(),
-              ImmutableSet.copyOf(fieldNames),
+              fieldNamesBuilder.build(),
               new FieldResolver(this, descriptor)::findField,
               new FieldResolver(this, extensions)::findField));
     }
@@ -158,19 +162,35 @@ private ImmutableMap<String, CelType> createEnumTypes(
   }
 
   private static class FieldResolver {
-    private final CelTypeProvider celTypeProvider;
+    private final ProtoMessageTypeProvider protoMessageTypeProvider;
     private final ImmutableMap<String, FieldDescriptor> fields;
 
-    private FieldResolver(CelTypeProvider celTypeProvider, Descriptor descriptor) {
+    private static ImmutableMap<String, FieldDescriptor> collectFieldDescriptorMap(ProtoMessageTypeProvider protoMessageTypeProvider, Descriptor descriptor) {
+      ImmutableMap.Builder<String, FieldDescriptor> builder = ImmutableMap.builder();
+      for (FieldDescriptor fd : descriptor.getFields()) {
+        builder.put(fd.getName(), fd);
+        if (protoMessageTypeProvider.allowJsonFieldNames) {
+          builder.put(fd.getJsonName(), fd);
+        }
+      }
+
+      return builder.buildKeepingLast();
+    }
+
+    private FieldResolver(
+        ProtoMessageTypeProvider protoMessageTypeProvider,
+        Descriptor descriptor
+        ) {
       this(
-          celTypeProvider,
-          descriptor.getFields().stream()
-              .collect(toImmutableMap(FieldDescriptor::getName, Function.identity())));
+          protoMessageTypeProvider,
+          collectFieldDescriptorMap(protoMessageTypeProvider, descriptor)
+      );
     }
 
     private FieldResolver(
-        CelTypeProvider celTypeProvider, ImmutableMap<String, FieldDescriptor> fields) {
-      this.celTypeProvider = celTypeProvider;
+        ProtoMessageTypeProvider protoMessageTypeProvider,
+        ImmutableMap<String, FieldDescriptor> fields) {
+      this.protoMessageTypeProvider = protoMessageTypeProvider;
       this.fields = fields;
     }
 
@@ -203,11 +223,11 @@ private Optional<CelType> findFieldInternal(FieldDescriptor fieldDescriptor) {
           String messageName = descriptor.getFullName();
           fieldType =
               CelTypes.getWellKnownCelType(messageName)
-                  .orElse(celTypeProvider.findType(descriptor.getFullName()).orElse(null));
+                  .orElse(protoMessageTypeProvider.findType(descriptor.getFullName()).orElse(null));
           break;
         case ENUM:
           EnumDescriptor enumDescriptor = fieldDescriptor.getEnumType();
-          fieldType = celTypeProvider.findType(enumDescriptor.getFullName()).orElse(null);
+          fieldType = protoMessageTypeProvider.findType(enumDescriptor.getFullName()).orElse(null);
           break;
         default:
           fieldType = PROTO_TYPE_TO_CEL_TYPE.get(fieldDescriptor.getType());
@@ -222,4 +242,66 @@ private Optional<CelType> findFieldInternal(FieldDescriptor fieldDescriptor) {
       return Optional.of(fieldType);
     }
   }
+
+  /** Builder for {@link ProtoMessageTypeProvider}. */
+  public static final class Builder {
+    private final ImmutableSet.Builder<FileDescriptor> fileDescriptors = ImmutableSet.builder();
+    private boolean allowJsonFieldNames;
+    private CelDescriptors celDescriptors;
+
+    /** Adds a {@link FileDescriptor} to the provider. */
+    public Builder addFileDescriptors(FileDescriptor... fileDescriptors) {
+      return addFileDescriptors(Arrays.asList(fileDescriptors));
+    }
+
+    /** Adds a collection of {@link FileDescriptor}s to the provider. */
+    public Builder addFileDescriptors(Iterable<FileDescriptor> fileDescriptors) {
+      this.fileDescriptors.addAll(fileDescriptors);
+      return this;
+    }
+
+    /** Adds a collection of {@link Descriptor}s. The parent file of each descriptor is added. */
+    public Builder addDescriptors(Iterable<Descriptor> descriptors) {
+      this.fileDescriptors.addAll(Iterables.transform(descriptors, Descriptor::getFile));
+      return this;
+    }
+
+    /** Adds a {@link FileDescriptorSet} to the provider. */
+    public Builder addFileDescriptorSet(FileDescriptorSet fileDescriptorSet) {
+      this.fileDescriptors.addAll(FileDescriptorSetConverter.convert(fileDescriptorSet));
+      return this;
+    }
+
+    public Builder setAllowJsonFieldNames(boolean allowJsonFieldNames) {
+      this.allowJsonFieldNames = allowJsonFieldNames;
+      return this;
+    }
+
+    public Builder setCelDescriptors(CelDescriptors celDescriptors) {
+      this.celDescriptors = celDescriptors;
+      return this;
+    }
+
+    /** Builds the {@link ProtoMessageTypeProvider}. */
+    public ProtoMessageTypeProvider build() {
+      // CelDescriptors celDescriptors = CelDescriptorUtil.getAllDescriptorsFromFileDescriptor(fileDescriptors.build());
+      return new ProtoMessageTypeProvider(celDescriptors, allowJsonFieldNames);
+    }
+
+    private Builder() {}
+  }
+
+  private ProtoMessageTypeProvider(
+      CelDescriptors celDescriptors,
+      boolean allowJsonFieldNames
+  ) {
+    this.allowJsonFieldNames = allowJsonFieldNames;
+    this.allTypes =
+        ImmutableMap.<String, CelType>builder()
+            .putAll(createEnumTypes(celDescriptors.enumDescriptors()))
+            .putAll(
+                createProtoMessageTypes(
+                    celDescriptors.messageTypeDescriptors(), celDescriptors.extensionDescriptors()))
+            .buildOrThrow();
+  }
 }
diff --git a/common/src/test/java/dev/cel/common/types/BUILD.bazel b/common/src/test/java/dev/cel/common/types/BUILD.bazel
@@ -16,6 +16,7 @@ java_library(
         "//common/types:cel_types",
         "//common/types:message_type_provider",
         "//common/types:type_providers",
+        "//testing/protos:single_file_java_proto",
         "@cel_spec//proto/cel/expr:checked_java_proto",
         "@cel_spec//proto/cel/expr/conformance/proto2:test_all_types_java_proto",
         "@cel_spec//proto/cel/expr/conformance/proto3:test_all_types_java_proto",

diff --git a/common/src/test/java/dev/cel/common/types/ProtoMessageTypeProviderTest.java b/common/src/test/java/dev/cel/common/types/ProtoMessageTypeProviderTest.java
@@ -20,8 +20,10 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import dev.cel.common.types.CelTypeProvider.CombinedCelTypeProvider;
+import dev.cel.common.types.StructType.Field;
 import dev.cel.expr.conformance.proto2.TestAllTypes;
 import dev.cel.expr.conformance.proto2.TestAllTypesExtensions;
+import dev.cel.testing.testdata.SingleFileProto.SingleFile;
 import java.util.Optional;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -254,4 +256,22 @@ public void types_combinedDuplicateProviderIsSameAsFirst() {
     CombinedCelTypeProvider combined = new CombinedCelTypeProvider(proto3Provider, proto3Provider);
     assertThat(combined.types()).hasSize(proto3Provider.types().size());
   }
+
+  @Test
+  public void findField_withJsonNameOption() {
+    ProtoMessageTypeProvider typeProvider =
+        ProtoMessageTypeProvider.newBuilder()
+            .addFileDescriptors(SingleFile.getDescriptor().getFile())
+            .setAllowJsonFieldNames(true)
+            .build();
+
+    ProtoMessageType msgType = (ProtoMessageType) typeProvider.findType(SingleFile.getDescriptor().getFullName()).get();
+
+    // Note that these are the same fields, with json_name option set
+    Optional<Field> snakeCasedField = msgType.findField("snake_cased");
+    Optional<Field> jsonNameField = msgType.findField("camelCased");
+
+    assertThat(snakeCasedField).hasValue(Field.of("snake_cased", SimpleType.STRING));
+    assertThat(jsonNameField).hasValue(Field.of("camelCased", SimpleType.STRING));
+  }
 }
diff --git a/runtime/src/main/java/dev/cel/runtime/DescriptorMessageProvider.java b/runtime/src/main/java/dev/cel/runtime/DescriptorMessageProvider.java
@@ -180,6 +180,15 @@ private FieldDescriptor findField(Descriptor descriptor, String fieldName) {
       }
     }
 
+    if (fieldDescriptor == null && celOptions.enableJsonFieldNames()) {
+      for (FieldDescriptor fd : descriptor.getFields()) {
+        if (fd.getJsonName().equals(fieldName)) {
+          fieldDescriptor = fd;
+          break;
+        }
+      }
+    }
+
     if (fieldDescriptor == null) {
       throw new IllegalArgumentException(
           String.format(

diff --git a/testing/src/test/resources/protos/single_file.proto b/testing/src/test/resources/protos/single_file.proto
@@ -26,4 +26,5 @@ message SingleFile {
 
   string name = 1;
   Path path = 2;
+  string snake_cased = 3 [json_name = "camelCased"];
 }