Implement MessageOneofRule

packages/protovalidate-testing/package.json

@@ -6,7 +6,7 @@
   },
   "scripts": {
     "install-protovalidate-conformance": "node scripts/install-protovalidate-conformance.js",
-    "generate": "buf generate buf.build/bufbuild/protovalidate-testing:v1.0.0-rc.1",
+    "generate": "buf generate buf.build/bufbuild/protovalidate-testing:v1.0.0-rc.2",
     "postgenerate": "license-header src/gen",
     "test": "protovalidate-conformance --strict_message --strict_error --expected_failures=expected-failures.yaml -- tsx src/executor.ts",
     "format": "biome format --write",

packages/protovalidate/README.md

@@ -50,7 +50,7 @@ if (result.kind !== "valid") {
 
 > [!NOTE]
 > 
-> This version is compatible with [buf.build/bufbuild/protovalidate](https://buf.build/bufbuild/protovalidate) <!-- upstreamProtovalidateRef -->v1.0.0-rc.1<!-- upstreamProtovalidateRef -->
+> This version is compatible with [buf.build/bufbuild/protovalidate](https://buf.build/bufbuild/protovalidate) <!-- upstreamProtovalidateRef -->v1.0.0-rc.2<!-- upstreamProtovalidateRef -->
 >
 > It requires the Protobuf runtime [@bufbuild/protobuf](https://www.npmjs.com/package/@bufbuild/protobuf).
 

packages/protovalidate/package.json

@@ -16,7 +16,7 @@
     "directory": "packages/protovalidate"
   },
   "scripts": {
-    "fetch-proto": "buf export buf.build/bufbuild/protovalidate:v1.0.0-rc.1 --output proto",
+    "fetch-proto": "buf export buf.build/bufbuild/protovalidate:v1.0.0-rc.2 --output proto",
     "postfetch-proto": "license-header proto",
     "generate": "buf generate",
     "postgenerate": "license-header src/gen",

packages/protovalidate/proto/buf/validate/validate.proto

@@ -76,7 +76,7 @@ extend google.protobuf.FieldOptions {
 // `Rule` represents a validation rule written in the Common Expression
 // Language (CEL) syntax. Each Rule includes a unique identifier, an
 // optional error message, and the CEL expression to evaluate. For more
-// information on CEL, [see our documentation](https://github.com/bufbuild/protovalidate/blob/main/docs/cel.md).
+// information, [see our documentation](https://buf.build/docs/protovalidate/schemas/custom-rules/).
 //
 // ```proto
 // message Foo {
@@ -121,8 +121,8 @@ message MessageRules {
   optional bool disabled = 1;
 
   // `cel` is a repeated field of type Rule. Each Rule specifies a validation rule to be applied to this message.
-  // These rules are written in Common Expression Language (CEL) syntax. For more information on
-  // CEL, [see our documentation](https://github.com/bufbuild/protovalidate/blob/main/docs/cel.md).
+  // These rules are written in Common Expression Language (CEL) syntax. For more information,
+  // [see our documentation](https://buf.build/docs/protovalidate/schemas/custom-rules/).
   //
   //
   // ```proto
@@ -137,6 +137,46 @@ message MessageRules {
   // }
   // ```
   repeated Rule cel = 3;
+
+  // `oneof` is a repeated field of type MessageOneofRule that specifies a list of fields
+  // of which at most one can be present. If `required` is also specified, then exactly one
+  // of the specified fields _must_ be present.
+  //
+  // This will enforce oneof-like constraints with a few features not provided by
+  // actual Protobuf oneof declarations:
+  //   1. Repeated and map fields are allowed in this validation. In a Protobuf oneof,
+  //      only scalar fields are allowed.
+  //   2. Fields with implicit presence are allowed. In a Protobuf oneof, all member
+  //      fields have explicit presence. This means that, for the purpose of determining
+  //      how many fields are set, explicitly setting such a field to its zero value is
+  //      effectively the same as not setting it at all.
+  //   3. This will generate validation errors when unmarshalling, even from the binary
+  //      format. With a Protobuf oneof, if multiple fields are present in the serialized
+  //      form, earlier values are usually silently ignored when unmarshalling, with only
+  //      the last field being present when unmarshalling completes.
+  //
+  //
+  // ```proto
+  // message MyMessage {
+  //   // Only one of `field1` or `field2` _can_ be present in this message.
+  //   option (buf.validate.message).oneof = { fields: ["field1", "field2"] };
+  //   // Only one of `field3` or `field4` _must_ be present in this message.
+  //   option (buf.validate.message).oneof = { fields: ["field3", "field4"], required: true };
+  //   string field1 = 1;
+  //   bytes field2 = 2;
+  //   bool field3 = 3;
+  //   int32 field4 = 4;
+  // }
+  // ```
+  repeated MessageOneofRule oneof = 4;
+}
+
+message MessageOneofRule {
+  // A list of field names to include in the oneof. All field names must be
+  // defined in the message.
+  repeated string fields = 1;
+  // If true, one of the fields specified _must_ be set.
+  optional bool required = 2;
 }
 
 // The `OneofRules` message type enables you to manage rules for
@@ -166,8 +206,8 @@ message OneofRules {
 // the field, the correct set should be used to ensure proper validations.
 message FieldRules {
   // `cel` is a repeated field used to represent a textual expression
-  // in the Common Expression Language (CEL) syntax. For more information on
-  // CEL, [see our documentation](https://github.com/bufbuild/protovalidate/blob/main/docs/cel.md).
+  // in the Common Expression Language (CEL) syntax. For more information,
+  // [see our documentation](https://buf.build/docs/protovalidate/schemas/custom-rules/).
   //
   // ```proto
   // message MyMessage {
@@ -251,8 +291,8 @@ message FieldRules {
 // multiple fields.
 message PredefinedRules {
   // `cel` is a repeated field used to represent a textual expression
-  // in the Common Expression Language (CEL) syntax. For more information on
-  // CEL, [see our documentation](https://github.com/bufbuild/protovalidate/blob/main/docs/cel.md).
+  // in the Common Expression Language (CEL) syntax. For more information,
+  // [see our documentation](https://buf.build/docs/protovalidate/schemas/predefined-rules/).
   //
   // ```proto
   // message MyMessage {
@@ -276,7 +316,7 @@ message PredefinedRules {
 // Specifies how FieldRules.ignore behaves. See the documentation for
 // FieldRules.required for definitions of "populated" and "nullable".
 enum Ignore {
-  // Validation is only skipped if it's an unpopulated nullable fields.
+  // Validation is only skipped if it's an unpopulated nullable field.
   //
   // ```proto
   // syntax="proto3";
@@ -3809,7 +3849,7 @@ message StringRules {
   extensions 1000 to max;
 }
 
-// WellKnownRegex contain some well-known patterns.
+// KnownRegex contains some well-known patterns.
 enum KnownRegex {
   KNOWN_REGEX_UNSPECIFIED = 0;
 
@@ -4816,7 +4856,7 @@ message TimestampRules {
 }
 
 // `Violations` is a collection of `Violation` messages. This message type is returned by
-// protovalidate when a proto message fails to meet the requirements set by the `Rule` validation rules.
+// Protovalidate when a proto message fails to meet the requirements set by the `Rule` validation rules.
 // Each individual violation is represented by a `Violation` message.
 message Violations {
   // `violations` is a repeated field that contains all the `Violation` messages corresponding to the violations detected.
@@ -4828,11 +4868,42 @@ message Violations {
 // caused the violation, the specific rule that wasn't fulfilled, and a
 // human-readable error message.
 //
+// For example, consider the following message:
+//
+// ```proto
+// message User {
+//     int32 age = 1 [(buf.validate.field).cel = {
+//         id: "user.age",
+//         expression: "this < 18 ? 'User must be at least 18 years old' : ''",
+//     }];
+// }
+// ```
+//
+// It could produce the following violation:
+//
 // ```json
 // {
-//   "fieldPath": "bar",
-//   "ruleId": "foo.bar",
-//   "message": "bar must be greater than 0"
+//   "ruleId": "user.age",
+//   "message": "User must be at least 18 years old",
+//   "field": {
+//     "elements": [
+//       {
+//         "fieldNumber": 1,
+//         "fieldName": "age",
+//         "fieldType": "TYPE_INT32"
+//       }
+//     ]
+//   },
+//   "rule": {
+//     "elements": [
+//       {
+//         "fieldNumber": 23,
+//         "fieldName": "cel",
+//         "fieldType": "TYPE_MESSAGE",
+//         "index": "0"
+//       }
+//     ]
+//   }
 // }
 // ```
 message Violation {
@@ -4857,7 +4928,7 @@ message Violation {
   // ```
   optional FieldPath field = 5;
 
-  // `rule` is a machine-readable path that points to the specific rule rule that failed validation.
+  // `rule` is a machine-readable path that points to the specific rule that failed validation.
   // This will be a nested field starting from the FieldRules of the field that failed validation.
   // For custom rules, this will provide the path of the rule, e.g. `cel[0]`.
   //

packages/protovalidate/src/cel.ts

@@ -21,7 +21,7 @@ import {
   type Registry,
   ScalarType,
 } from "@bufbuild/protobuf";
-import { type Path, type ReflectMessageGet } from "@bufbuild/protobuf/reflect";
+import type { Path, ReflectMessageGet } from "@bufbuild/protobuf/reflect";
 import { type Timestamp, timestampNow } from "@bufbuild/protobuf/wkt";
 import {
   type CelEnv,

packages/protovalidate/src/eval.test.ts

@@ -44,6 +44,7 @@ void suite("check buf.validate.*Rules fields", () => {
     StringRulesSchema.field.strict,
     MessageRulesSchema.field.cel,
     MessageRulesSchema.field.disabled,
+    MessageRulesSchema.field.oneof,
     OneofRulesSchema.field.required,
     FieldRulesSchema.field.cel,
     FieldRulesSchema.field.required,

packages/protovalidate/src/eval.ts

@@ -271,3 +271,31 @@ export class EvalAnyRules implements Eval<ReflectMessage> {
     return this.in.length + this.notIn.length == 0;
   }
 }
+
+/**
+ * buf.validate.MessageOneofRule does not use CEL expressions. This implements custom logic for this rule.
+ */
+export class EvalMessageOneofRule implements Eval<ReflectMessage> {
+  constructor(
+    private readonly fields: DescField[],
+    private readonly required: boolean,
+  ) {}
+  eval(val: ReflectMessage, cursor: Cursor) {
+    const setFields = this.fields.filter((field) => val.isSet(field));
+    if (setFields.length > 1) {
+      const oneofNames = this.fields.map((f) => f.name).join(", ");
+      cursor.violate(
+        `only one of ${oneofNames} can be set`,
+        "message.oneof",
+        [],
+      );
+    }
+    if (this.required && setFields.length == 0) {
+      const oneofNames = this.fields.map((f) => f.name).join(", ");
+      cursor.violate(`one of ${oneofNames} must be set`, "message.oneof", []);
+    }
+  }
+  prune(): boolean {
+    return this.fields.length == 0;
+  }
+}