omit defaults in yaml serialization loop (#15701)

Author: ScottSuarez

mmv1/api/async.go

@@ -15,25 +15,26 @@ package api
 
 import (
 	"log"
+	"reflect"
 	"strings"
 
+	"github.com/GoogleCloudPlatform/magic-modules/mmv1/api/utils"
 	"golang.org/x/exp/slices"
 	"gopkg.in/yaml.v3"
 )
 
 // Base class from which other Async classes can inherit.
 type Async struct {
+	// Describes an operation, one of "OpAsync", "PollAsync"
+	Type string `yaml:"type,omitempty"`
+
 	// Describes an operation
-	Operation *Operation
+	Operation *Operation `yaml:"operation,omitempty"`
 
 	// The list of methods where operations are used.
-	Actions []string
-
-	// Describes an operation, one of "OpAsync", "PollAsync"
-	Type string
-
-	OpAsync `yaml:",inline"`
+	Actions []string `yaml:"actions,omitempty"`
 
+	OpAsync   `yaml:",inline"`
 	PollAsync `yaml:",inline"`
 }
 
@@ -70,11 +71,11 @@ func NewAsync() *Async {
 
 // Represents an asynchronous operation definition
 type OpAsync struct {
-	Result OpAsyncResult
+	Result OpAsyncResult `yaml:"result,omitempty"`
 
 	// If true, include project as an argument to OperationWaitTime.
 	// It is intended for resources that calculate project/region from a selflink field
-	IncludeProject bool `yaml:"include_project"`
+	IncludeProject bool `yaml:"include_project,omitempty"`
 }
 
 type OpAsyncOperation struct {
@@ -110,26 +111,57 @@ type PollAsync struct {
 	TargetOccurrences int `yaml:"target_occurrences,omitempty"`
 }
 
+// newAsyncWithDefaults returns an Async object with default values set.
+func newAsyncWithDefaults() Async {
+	a := Async{
+		Actions: []string{"create", "delete", "update"},
+		Type:    "OpAsync",
+	}
+	return a
+}
+
 func (a *Async) UnmarshalYAML(value *yaml.Node) error {
-	a.Actions = []string{"create", "delete", "update"}
+	// Start with a struct containing all the default values.
+	*a = newAsyncWithDefaults()
+
 	type asyncAlias Async
 	aliasObj := (*asyncAlias)(a)
 
-	err := value.Decode(aliasObj)
-	if err != nil {
+	if err := value.Decode(aliasObj); err != nil {
 		return err
 	}
 
-	if a.Type == "" {
-		a.Type = "OpAsync"
-	}
 	if a.Type == "PollAsync" && a.TargetOccurrences == 0 {
 		a.TargetOccurrences = 1
 	}
 
 	return nil
 }
 
+// MarshalYAML implements a custom marshaller for the Async struct.
+// It omits fields that are set to their default values.
+func (a *Async) MarshalYAML() (interface{}, error) {
+	// Use a type alias to prevent infinite recursion during marshaling.
+	type asyncAlias Async
+
+	// Create a defaults object that reflects the defaults for the current object's state.
+	defaults := newAsyncWithDefaults()
+
+	// Use the generic helper for simple types. It returns a pointer to a clone.
+	clone, err := utils.OmitDefaultsForMarshaling(*a, defaults)
+	if err != nil {
+		return nil, err
+	}
+	clonePtr := clone.(*Async)
+
+	// The helper ignores slices, so we handle `Actions` manually on the clone.
+	if reflect.DeepEqual(clonePtr.Actions, defaults.Actions) {
+		clonePtr.Actions = nil
+	}
+
+	return (*asyncAlias)(clonePtr), nil
+}
+
 func (a *Async) Validate() {
 	if a.Type == "OpAsync" {
 		if a.Operation == nil {

mmv1/api/resource.go

@@ -218,7 +218,7 @@ type Resource struct {
 
 	// Examples in documentation. Backed by generated tests, and have
 	// corresponding OiCS walkthroughs.
-	Examples []*resource.Examples
+	Examples []*resource.Examples `yaml:"examples,omitempty"`
 
 	// Samples for generating tests and documentation
 	Samples []*resource.Sample `yaml:"samples,omitempty"`
@@ -240,6 +240,8 @@ type Resource struct {
 
 	Timeouts *Timeouts `yaml:"timeouts,omitempty"`
 
+	Async *Async `yaml:"async,omitempty"`
+
 	// An array of function names that determine whether an error is retryable.
 	ErrorRetryPredicates []string `yaml:"error_retry_predicates,omitempty"`
 
@@ -305,8 +307,6 @@ type Resource struct {
 	// Add a deprecation message for a resource that's been deprecated in the API.
 	DeprecationMessage string `yaml:"deprecation_message,omitempty"`
 
-	Async *Async
-
 	// Tag autogen resources so that we can track them. In the future this will
 	// control if a resource is continuously generated from public OpenAPI docs
 	AutogenStatus string `yaml:"autogen_status"`
@@ -428,7 +428,35 @@ func (r *Resource) UnmarshalYAML(value *yaml.Node) error {
 	return nil
 }
 
-func (r *Resource) SetDefault(product *Product) {
+// // MarshalYAML implements a custom marshaller to omit dynamic default values.
+func (r *Resource) MarshalYAML() (interface{}, error) {
+	type resourceAlias Resource
+
+	defaults := Resource{}
+
+	// Pre-populate fields needed for shallow default calculation.
+	defaults.Name = r.Name
+	defaults.ApiResourceTypeKind = r.ApiResourceTypeKind
+	defaults.SelfLink = r.SelfLink
+	defaults.MinVersion = r.MinVersion
+	// Calculate shallow defaults.
+	defaults.setShallowDefaults()
+	defaults.Name = ""
+	defaults.ApiResourceTypeKind = ""
+	defaults.SelfLink = ""
+	defaults.MinVersion = ""
+
+	clone, err := utils.OmitDefaultsForMarshaling(*r, defaults)
+	if err != nil {
+		return nil, err
+	}
+
+	return (*resourceAlias)(clone.(*Resource)), nil
+}
+
+// SetShallowDefaults calculates and sets default values for the immediate fields
+// of this Resource, without recursing into its children (Properties, etc.).
+func (r *Resource) setShallowDefaults() {
 	if r.CreateVerb == "" {
 		r.CreateVerb = "POST"
 	}
@@ -462,20 +490,25 @@ func (r *Resource) SetDefault(product *Product) {
 		}
 	}
 
+	if r.IamPolicy != nil && r.IamPolicy.MinVersion == "" {
+		r.IamPolicy.MinVersion = r.MinVersion
+	}
+	if r.Timeouts == nil {
+		r.Timeouts = NewTimeouts() // This only sets defaults if Timeouts is nil
+	}
+}
+
+// SetDefault sets default values for this Resource and all its properties.
+func (r *Resource) SetDefault(product *Product) {
+	r.setShallowDefaults() // Set defaults for the current level.
+
 	r.ProductMetadata = product
 	for _, property := range r.AllProperties() {
 		property.SetDefault(r)
 	}
 	for _, vf := range r.VirtualFields {
 		vf.SetDefault(r)
 	}
-	if r.IamPolicy != nil && r.IamPolicy.MinVersion == "" {
-		r.IamPolicy.MinVersion = r.MinVersion
-	}
-	if r.Timeouts == nil {
-		r.Timeouts = NewTimeouts()
-	}
-
 }
 
 func (r *Resource) Validate() {

mmv1/api/resource/examples.go

@@ -25,6 +25,7 @@ import (
 	"strings"
 	"text/template"
 
+	"github.com/GoogleCloudPlatform/magic-modules/mmv1/api/utils"
 	"github.com/GoogleCloudPlatform/magic-modules/mmv1/google"
 	"gopkg.in/yaml.v3"
 )
@@ -196,30 +197,25 @@ func (e *Examples) UnmarshalYAML(value *yaml.Node) error {
 }
 
 // MarshalYAML implements a custom marshaller for the Examples struct.
-// It omits the ConfigPath field if it's equal to its default generated value.
+// It uses a generic helper to omit fields that are set to their default values.
 func (e *Examples) MarshalYAML() (interface{}, error) {
-	// 1. Calculate the default value for ConfigPath based on the Name field.
-	//    This logic must mirror the one in UnmarshalYAML.
-	defaultPath := ""
+	// Use a type alias to prevent infinite recursion.
+	type exampleAlias Examples
+
+	// Create a defaults object by unmarshalling an empty node, which populates defaults.
+	// Here, we can create one manually based on the unmarshal logic.
+	defaults := Examples{}
 	if e.Name != "" {
-		defaultPath = DefaultConfigPath(e.Name)
+		defaults.ConfigPath = DefaultConfigPath(e.Name)
 	}
 
-	// 2. Create a shallow copy to avoid modifying the original struct.
-	//    This prevents the marshaling operation from having side effects.
-	clone := *e
-
-	// 3. If the current ConfigPath matches the default, clear it.
-	//    The `omitempty` tag will then cause the YAML marshaler to skip it.
-	if clone.ConfigPath == defaultPath {
-		clone.ConfigPath = ""
+	// Use the generic helper to create a clone with default values zeroed out.
+	clone, err := utils.OmitDefaultsForMarshaling(*e, defaults)
+	if err != nil {
+		return nil, err
 	}
 
-	// 4. Use a type alias to prevent infinite recursion.
-	//    The alias `exampleAlias` does not have this MarshalYAML method,
-	//    so calling the marshaler on it will use the default struct marshaler.
-	type exampleAlias Examples
-	return (*exampleAlias)(&clone), nil
+	return (*exampleAlias)(clone.(*Examples)), nil
 }
 
 // DefaultConfigPath returns the default path for an example's Terraform config.

mmv1/api/resource/iam_policy.go

@@ -17,6 +17,7 @@ import (
 	"log"
 	"slices"
 
+	"github.com/GoogleCloudPlatform/magic-modules/mmv1/api/utils"
 	"gopkg.in/yaml.v3"
 )
 
@@ -26,7 +27,7 @@ import (
 // See: https://cloud.google.com/iam/docs/overview
 type IamPolicy struct {
 	// boolean of if this binding should be generated
-	Exclude bool
+	Exclude bool `yaml:"exclude,omitempty"`
 
 	// boolean of if this binding should be generated
 	ExcludeTgc bool `yaml:"exclude_tgc,omitempty"`
@@ -81,7 +82,7 @@ type IamPolicy struct {
 
 	// Resource name may need a custom diff suppress function. Default is to use
 	// CompareSelfLinkOrResourceName
-	CustomDiffSuppress *string `yaml:"custom_diff_suppress"`
+	CustomDiffSuppress *string `yaml:"custom_diff_suppress,omitempty"`
 
 	// Some resources (IAP) use fields named differently from the parent resource.
 	// We need to use the parent's attributes to create an IAM policy, but they may not be
@@ -90,7 +91,7 @@ type IamPolicy struct {
 	// config with the test/example attributes of the IAM resource.
 	ExampleConfigBody string `yaml:"example_config_body,omitempty"`
 
-	SampleConfigBody string `yaml:"sample_config_body"`
+	SampleConfigBody string `yaml:"sample_config_body,omitempty"`
 
 	// How the API supports IAM conditions
 	IamConditionsRequestType string `yaml:"iam_conditions_request_type,omitempty"`
@@ -123,26 +124,53 @@ type IamPolicy struct {
 	DeprecationMessage string `yaml:"deprecation_message,omitempty"`
 }
 
+// newIamPolicyWithDefaults returns an IamPolicy object with default values set.
+func newIamPolicyWithDefaults() IamPolicy {
+	return IamPolicy{
+		MethodNameSeparator:     "/",
+		FetchIamPolicyVerb:      "GET",
+		FetchIamPolicyMethod:    "getIamPolicy",
+		SetIamPolicyVerb:        "POST",
+		SetIamPolicyMethod:      "setIamPolicy",
+		WrappedPolicyObj:        true,
+		AllowedIamRole:          "roles/viewer",
+		ParentResourceAttribute: "id",
+		SubstituteZoneValue:     true,
+	}
+}
+
+// UnmarshalYAML implements a custom unmarshaler for the IamPolicy struct.
+// It sets default values and then decodes the YAML over them.
 func (p *IamPolicy) UnmarshalYAML(value *yaml.Node) error {
-	p.MethodNameSeparator = "/"
-	p.FetchIamPolicyVerb = "GET"
-	p.FetchIamPolicyMethod = "getIamPolicy"
-	p.SetIamPolicyVerb = "POST"
-	p.SetIamPolicyMethod = "setIamPolicy"
-	p.WrappedPolicyObj = true
-	p.AllowedIamRole = "roles/viewer"
-	p.ParentResourceAttribute = "id"
-	p.SubstituteZoneValue = true
+	// Start with a struct containing all the default values.
+	*p = newIamPolicyWithDefaults()
 
+	// Use a type alias to prevent recursion when decoding.
 	type iamPolicyAlias IamPolicy
 	aliasObj := (*iamPolicyAlias)(p)
 
-	err := value.Decode(aliasObj)
+	// Decode the provided YAML, which will overwrite any default values that are specified.
+	return value.Decode(aliasObj)
+}
+
+// MarshalYAML implements a custom marshaller for the IamPolicy struct.
+// It uses a generic helper to omit fields that are set to their default values.
+func (p *IamPolicy) MarshalYAML() (interface{}, error) {
+	// Use a type alias to prevent infinite recursion during marshaling.
+	type iamPolicyAlias IamPolicy
+
+	// Create a defaults object and then use the generic helper to create a
+	// clone with default values zeroed out for marshaling.
+	defaults := newIamPolicyWithDefaults()
+	clone, err := utils.OmitDefaultsForMarshaling(*p, defaults)
 	if err != nil {
-		return err
+		return nil, err
 	}
 
-	return nil
+	// The helper returns an interface{} containing a pointer to the clone.
+	// We cast it to the alias type to ensure the marshaller uses the default
+	// behavior for the struct, but without this custom MarshalYAML method.
+	return (*iamPolicyAlias)(clone.(*IamPolicy)), nil
 }
 
 func (p *IamPolicy) Validate(rName string) {