132/133 should use resource_reference_child_type (#114)

Author: rambleraptor

docs/rules/0132/resource-reference-type.md

@@ -2,7 +2,7 @@
 rule:
   aep: 132
   name: [core, '0132', resource-reference-type]
-  summary: List should use a `child_type` reference to the paginated resource.
+  summary: List should use `resource_reference_child_type` to reference the paginated resource.
 permalink: /132/resource-reference-type
 redirect_from:
   - /0132/resource-reference-type
@@ -11,15 +11,15 @@ redirect_from:
 # List methods: Parent field resource reference
 
 This rule enforces that all `List` standard methods with a `string parent`
-field use a proper `(aep.api.field_info).resource_reference`, that being either a
-`child_type` referring to the pagianted resource or a `type` referring directly
-to the parent resource, as mandated in [AEP-132][].
+field use a proper `(aep.api.field_info).resource_reference_child_type` to refer to the
+paginated resource, as mandated in [AEP-132][].
 
 ## Details
 
-This rule looks at any message matching `List*Request` and complains if the 
-`(aep.api.field_info).resource_reference` on the `parent` field refers to the wrong
-resource.
+This rule looks at any message matching `List*Request` and complains if the
+`(aep.api.field_info).resource_reference_child_type` or `(aep.api.field_info).resource_reference`
+on the `parent` field refers to the wrong resource. The preferred approach is to use
+`resource_reference_child_type` to reference the child resource being paginated.
 
 ## Examples
 
@@ -28,9 +28,8 @@ resource.
 ```proto
 // Incorrect.
 message ListBooksRequest {
-  // `child_type` should be used instead of `type` when referring to the
-  // paginated resource on a parent field.
-  string parent = 1 [(aep.api.field_info).resource_reference.type = "library.googleapis.com/Book"];
+  // Should reference the correct child resource type.
+  string parent = 1 [(aep.api.field_info).resource_reference_child_type = "library.googleapis.com/Shelf"];
   int32 page_size = 2;
   string page_token = 3;
 }
@@ -41,7 +40,7 @@ message ListBooksRequest {
 ```proto
 // Correct.
 message ListBooksRequest {
-  string parent = 1 [(aep.api.field_info).resource_reference.child_type = "library.googleapis.com/Book"];
+  string parent = 1 [(aep.api.field_info).resource_reference_child_type = "library.googleapis.com/Book"];
   int32 page_size = 2;
   string page_token = 3;
 }
@@ -56,7 +55,7 @@ Remember to also include an [aep.dev/not-precedent][] comment explaining why.
 message ListBooksRequest {
   // (-- api-linter: core::0132::resource-reference-type=disabled
   //     aep.dev/not-precedent: We need to do this because reasons. --)
-  string parent = 1 [(aep.api.field_info).resource_reference.type = "library.googleapis.com/Book"];
+  string parent = 1 [(aep.api.field_info).resource_reference_child_type = "library.googleapis.com/Shelf"];
   int32 page_size = 2;
   string page_token = 3;
 }

docs/rules/0133/resource-reference-type.md

@@ -2,7 +2,9 @@
 rule:
   aep: 133
   name: [core, '0133', resource-reference-type]
-  summary: Create should use a `child_type` reference to the created resource.
+  summary:
+    Create should use `resource_reference_child_type` to reference the created
+    resource.
 permalink: /133/resource-reference-type
 redirect_from:
   - /0133/resource-reference-type
@@ -11,15 +13,17 @@ redirect_from:
 # Create methods: Parent field resource reference
 
 This rule enforces that all `Create` standard methods with a `string parent`
-field use a proper `(aep.api.field_info).resource_reference`, that being either a
-`child_type` referring to the created resource or a `type` referring directly
-to the parent resource, as mandated in [AEP-133][].
+field use a proper `(aep.api.field_info).resource_reference_child_type` or
+`(aep.api.field_info.).resource_reference` to refer to the created resource, as
+mandated in [AEP-133][].
 
 ## Details
 
-This rule looks at any message matching `Create*Request` and complains if the 
-`(aep.api.field_info).resource_reference` on the `parent` field refers to the wrong
-resource.
+This rule looks at any message matching `Create*Request` and complains if the
+`(aep.api.field_info).resource_reference_child_type` or
+`(aep.api.field_info).resource_reference` on the `parent` field refers to the
+wrong resource. The preferred approach is to use
+`resource_reference_child_type` to reference the child resource being created.
 
 ## Examples
 
@@ -28,9 +32,8 @@ resource.
 ```proto
 // Incorrect.
 message CreateBooksRequest {
-  // `child_type` should be used instead of `type` when referring to the
-  // created resource on a parent field.
-  string parent = 1 [(aep.api.field_info).resource_reference.type = "library.googleapis.com/Book"];
+  // Should reference the correct child resource type.
+  string parent = 1 [(aep.api.field_info).resource_reference_child_type = "library.googleapis.com/Shelf"];
   Book book = 2;
 }
 ```
@@ -40,7 +43,7 @@ message CreateBooksRequest {
 ```proto
 // Correct.
 message CreateBooksRequest {
-  string parent = 1 [(aep.api.field_info).resource_reference.child_type = "library.googleapis.com/Book"];
+  string parent = 1 [(aep.api.field_info).resource_reference_child_type = "library.googleapis.com/Book"];
   Book book = 2;
 }
 ```
@@ -54,7 +57,7 @@ Remember to also include an [aep.dev/not-precedent][] comment explaining why.
 message CreateBooksRequest {
   // (-- api-linter: core::0133::resource-reference-type=disabled
   //     aep.dev/not-precedent: We need to do this because reasons. --)
-  string parent = 1 [(aep.api.field_info).resource_reference.type = "library.googleapis.com/Book"];
+  string parent = 1 [(aep.api.field_info).resource_reference_child_type = "library.googleapis.com/Shelf"];
   Book book = 2;
 }
 ```

go.mod

@@ -4,7 +4,7 @@ go 1.24.0
 
 require (
 	bitbucket.org/creachadair/stringset v0.0.14
-	buf.build/gen/go/aep/api/protocolbuffers/go v1.36.10-20251016045117-f9844266f27f.1
+	buf.build/gen/go/aep/api/protocolbuffers/go v1.36.10-20251102152130-5f3e69139afa.1
 	buf.build/go/bufplugin v0.9.0
 	cloud.google.com/go/longrunning v0.7.0
 	github.com/bmatcuk/doublestar/v4 v4.9.1

go.sum

@@ -2,6 +2,8 @@ bitbucket.org/creachadair/stringset v0.0.14 h1:t1ejQyf8utS4GZV/4fM+1gvYucggZkfhb
 bitbucket.org/creachadair/stringset v0.0.14/go.mod h1:Ej8fsr6rQvmeMDf6CCWMWGb14H9mz8kmDgPPTdiVT0w=
 buf.build/gen/go/aep/api/protocolbuffers/go v1.36.10-20251016045117-f9844266f27f.1 h1:jK64CGldQTGX2ESi+v41uERp+z28OFqGyAn/T/Qs8Q0=
 buf.build/gen/go/aep/api/protocolbuffers/go v1.36.10-20251016045117-f9844266f27f.1/go.mod h1:JOZpZ+zS3G2OKO02hKlEazAGR5X9uVpFyeCamXBXg5c=
+buf.build/gen/go/aep/api/protocolbuffers/go v1.36.10-20251102152130-5f3e69139afa.1 h1:SEKgDODwWdsVL9nnOPkFBlZ9wAuO7kRQNobSZb5JR7I=
+buf.build/gen/go/aep/api/protocolbuffers/go v1.36.10-20251102152130-5f3e69139afa.1/go.mod h1:JOZpZ+zS3G2OKO02hKlEazAGR5X9uVpFyeCamXBXg5c=
 buf.build/gen/go/bufbuild/bufplugin/protocolbuffers/go v1.36.10-20250718181942-e35f9b667443.1 h1:FzJGrb8r7vir+P3zJ5Ebey8p54LYTYtQsrM/U35YO9Q=
 buf.build/gen/go/bufbuild/bufplugin/protocolbuffers/go v1.36.10-20250718181942-e35f9b667443.1/go.mod h1:E6HwqUm4Ag7bXtg/tX7jHWO7CgpknbmeACgDax0icV0=
 buf.build/gen/go/bufbuild/protovalidate/protocolbuffers/go v1.36.10-20250912141014-52f32327d4b0.1 h1:31on4W/yPcV4nZHL4+UCiCvLPsMqe/vJcNg8Rci0scc=

rules/aep0121/no_mutable_cycles.go

@@ -47,18 +47,23 @@ func findCycles(start string, node *desc.MessageDescriptor, seen stringset.Set,
 		}
 		ref := utils.GetResourceReference(f)
 		// Skip indirect references for now.
-		if ref.GetChildType() != "" {
+		if len(ref.GetChildType()) > 0 {
 			continue
 		}
-		if ref.GetType() == start {
+		types := ref.GetType()
+		if len(types) == 0 {
+			continue
+		}
+		refType := types[0]
+		if refType == start {
 			cycle := strings.Join(append(chain, start), " > ")
 			problems = append(problems, lint.Problem{
 				Message:    "mutable resource reference introduces a reference cycle:\n" + cycle,
 				Descriptor: f,
 				Location:   locations.FieldResourceReference(f),
 			})
-		} else if !seen.Contains(ref.GetType()) {
-			next := utils.FindResourceMessage(ref.GetType(), node.GetFile())
+		} else if !seen.Contains(refType) {
+			next := utils.FindResourceMessage(refType, node.GetFile())
 			// Skip unresolvable references.
 			if next == nil {
 				continue

rules/aep0127/http_template_pattern.go

@@ -66,16 +66,21 @@ func httpResourceReferences(httpRule *utils.HTTPRule, msg *desc.MessageDescripto
 
 		// Extract the name of the resource referenced by this field.
 		ref := utils.GetResourceReference(field)
-		if ref == nil || ref.GetChildType() != "" {
+		if ref == nil || len(ref.GetChildType()) > 0 {
 			// TODO(#1047): Support the case where a resource has
 			// multiple parent resources.
 			continue
 		}
 
+		types := ref.GetType()
+		if len(types) == 0 {
+			continue
+		}
+
 		resourceRefs = append(resourceRefs, resourceReference{
 			fieldPath:       fieldPath,
 			pathTemplate:    template,
-			resourceRefName: ref.GetType(),
+			resourceRefName: types[0],
 		})
 	}
 	return resourceRefs

rules/aep0131/request_path_reference_type.go

@@ -28,7 +28,7 @@ var requestPathReferenceType = &lint.FieldRule{
 		return utils.IsGetRequestMessage(f.GetOwner()) && f.GetName() == "path" && utils.GetResourceReference(f) != nil
 	},
 	LintField: func(f *desc.FieldDescriptor) []lint.Problem {
-		if ref := utils.GetResourceReference(f); ref.GetType() == "" {
+		if ref := utils.GetResourceReference(f); len(ref.GetType()) == 0 || ref.GetType()[0] == "" {
 			return []lint.Problem{{
 				Message:    fmt.Sprintf("The `%s` field `(aep.api.field_info).resource_reference` annotation should be a direct `type` reference.", f.GetName()),
 				Descriptor: f,

rules/aep0132/request_parent_valid_reference.go

@@ -29,12 +29,14 @@ var requestParentValidReference = &lint.FieldRule{
 	RuleType: lint.NewRuleType(lint.MustRule),
 	OnlyIf: func(f *desc.FieldDescriptor) bool {
 		ref := utils.GetResourceReference(f)
-		return utils.IsListRequestMessage(f.GetOwner()) && f.GetName() == "parent" && ref != nil && ref.GetType() != ""
+		types := ref.GetType()
+		return utils.IsListRequestMessage(f.GetOwner()) && f.GetName() == "parent" && ref != nil && len(types) > 0
 	},
 	LintField: func(f *desc.FieldDescriptor) []lint.Problem {
 		p := f.GetParent()
 		msg, _ := p.(*desc.MessageDescriptor)
-		res := utils.GetResourceReference(f).GetType()
+		types := utils.GetResourceReference(f).GetType()
+		res := types[0]
 
 		response := utils.FindMessage(f.GetFile(), strings.Replace(msg.GetName(), "Request", "Response", 1))
 		if response == nil {

rules/aep0132/resource_reference_type.go

@@ -45,26 +45,26 @@ var resourceReferenceType = &lint.MethodRule{
 		parent := m.GetInputType().FindFieldByName("parent")
 		ref := utils.GetResourceReference(parent)
 
-		// In AEP format, resource_reference is just a string. When used in List methods,
-		// it should match the child resource type. The old Google API format distinguishes
-		// between `type` and `child_type`, but AEP format just uses the string value.
-		// If child_type is set (Google API format), check it. Otherwise, check the type field
-		// and treat it as an implicit child_type reference.
-		if ref.GetChildType() != "" {
-			// Google API format with explicit child_type
-			if resource.GetType() != ref.GetChildType() {
+		// Check resource reference matches the child resource type.
+		// In AEP format, use resource_reference_child_type to reference the child resource.
+		// For backwards compatibility, resource_reference (type) is also supported.
+		childTypes := ref.GetChildType()
+		types := ref.GetType()
+
+		if len(childTypes) > 0 {
+			// AEP format with resource_reference_child_type
+			if resource.GetType() != childTypes[0] {
 				return []lint.Problem{{
-					Message:    "List should use a `child_type` reference to the paginated resource.",
+					Message:    "List should use `resource_reference_child_type` to reference the paginated resource.",
 					Descriptor: parent,
 					Location:   locations.FieldResourceReference(parent),
 				}}
 			}
-		} else if ref.GetType() != "" {
-			// AEP format or Google API format with only type set
-			// In AEP format, this should match the child resource type
-			if resource.GetType() != ref.GetType() {
+		} else if len(types) > 0 {
+			// AEP format with resource_reference only (backwards compatibility)
+			if resource.GetType() != types[0] {
 				return []lint.Problem{{
-					Message:    "List should use a `child_type` reference to the paginated resource.",
+					Message:    "List should use `resource_reference_child_type` to reference the paginated resource.",
 					Descriptor: parent,
 					Location:   locations.FieldResourceReference(parent),
 				}}

rules/aep0132/resource_reference_type_test.go

@@ -30,14 +30,16 @@ option (google.api.resource) = {
 
 	// Set up testing permutations.
 	tests := []struct {
-		testName string
-		TypeName string
+		testName           string
+		Annotation         string
 		ResourceAnnotation string
 		problems           testutils.Problems
 	}{
-		{"ValidMatch", "library.googleapis.com/Book", bookResource, nil},
-		{"InvalidMismatch", "library.googleapis.com/Shelf", bookResource, testutils.Problems{{Message: "`child_type`"}}},
-		{"SkipNoResource", "library.googleapis.com/Book", "", nil},
+		{"ValidMatch_resource_reference", `resource_reference = "library.googleapis.com/Book"`, bookResource, nil},
+		{"InvalidMismatch_resource_reference", `resource_reference = "library.googleapis.com/Shelf"`, bookResource, testutils.Problems{{Message: "`resource_reference_child_type`"}}},
+		{"ValidMatch_resource_reference_child_type", `resource_reference_child_type = "library.googleapis.com/Book"`, bookResource, nil},
+		{"InvalidMismatch_resource_reference_child_type", `resource_reference_child_type = "library.googleapis.com/Shelf"`, bookResource, testutils.Problems{{Message: "`resource_reference_child_type`"}}},
+		{"SkipNoResource", `resource_reference = "library.googleapis.com/Book"`, "", nil},
 	}
 
 	// Run each test.
@@ -50,7 +52,7 @@ option (google.api.resource) = {
 					rpc ListBooks(ListBooksRequest) returns (ListBooksResponse) {}
 				}
 				message ListBooksRequest {
-					string parent = 1 [(aep.api.field_info).resource_reference = "{{ .TypeName }}"];
+					string parent = 1 [(aep.api.field_info).{{ .Annotation }}];
 				}
 				message ListBooksResponse {
 					repeated string unreachable = 2;