Extend GoTag configuration to nested fields and attributes (#487)

Building upon the introduced `GoTag` configuration in 3753ca3, this
commit expands the functionality to cover nested fields and attributes.
Now users will be able to set custom Go Tags for nested fields using
JSONPath style directives. e.g:

```yaml
resources:
  AccessEntries:
    fields:
      AccessPolicies.AccessScope.Type:
        go_tag: json:"type,omitempty"
```

This patch also refactors `updateTypeDefAttributeWithReference` function
to reuse the code for finding and mutating Attribute objects.

Tested with eks-controller (`AccessPolicies.AccessScope.Type`).

Signed-off-by: Amine Hilaly <hilalyamine@gmail.com>

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Author: a-hilaly

pkg/model/attr.go

@@ -14,6 +14,8 @@
 package model
 
 import (
+	"fmt"
+
 	"github.com/aws-controllers-k8s/pkg/names"
 	awssdkmodel "github.com/aws/aws-sdk-go/private/model/api"
 )
@@ -22,6 +24,7 @@ type Attr struct {
 	Names  names.Names
 	GoType string
 	Shape  *awssdkmodel.Shape
+	GoTag  string
 }
 
 func NewAttr(
@@ -35,3 +38,13 @@ func NewAttr(
 		Shape:  shape,
 	}
 }
+
+// GetGoTag returns the Go Tag to inject for this attribute. If the GoTag
+// field is not empty, it will be used. Otherwise, one will be generated
+// from the attribute's name.
+func (a *Attr) GetGoTag() string {
+	if a.GoTag != "" {
+		return a.GoTag
+	}
+	return fmt.Sprintf("`json:\"%s,omitempty\"`", a.Names.CamelLower)
+}

pkg/model/model.go

@@ -502,21 +502,32 @@ func (m *Model) processNestedFieldTypeDefs(
 				replaceSecretAttrGoType(crd, field, tdefs)
 			}
 			if field.FieldConfig.References != nil {
-				updateTypeDefAttributeWithReference(fieldPath, tdefs, crd)
+				updateTypeDefAttributeWithReference(crd, fieldPath, tdefs)
+			}
+			if field.FieldConfig.GoTag != nil {
+				setTypeDefAttributeGoTag(crd, fieldPath, field, tdefs)
 			}
 		}
 	}
 }
 
-// updateTypeDefAttributeWithReference adds a new AWSResourceReference attribute
-// for the corresponding attribute represented by fieldPath of nested field
-func updateTypeDefAttributeWithReference(fieldPath string, tdefs []*TypeDef, crd *CRD) {
+// getAttributeFromPath extracts the parent TypeDef and the target attribute for
+// the corresponding fieldPath of nested field. This function should only be
+// called for nested fieldPath. Non-nested fieldPath should be handled by higher
+// level functions.
+//
+// This function doesn't return an error "urgh" because a lot of the code
+// generation code is written in a way that panics are used to indicate
+// programmer error. This is one of those cases.
+//
+// NOTE(a-hilaly): Consider refactoring the code generation code to flow back
+// errors instead of panicking.
+func getAttributeFromPath(crd *CRD, fieldPath string, tdefs []*TypeDef) (parentTypeDef *TypeDef, target *Attr) {
 	fp := ackfp.FromString(fieldPath)
 	if fp.Size() < 2 {
-		// TypeDef should only be updated with Reference fields for nested fieldPath.
-		// For non-nested fieldPath, the references are added directly to the resource
-		// Spec.
-		return
+		// This function should only be called for nested fieldPath. Non-nested
+		// fieldPath should be handled by higher level functions.
+		return nil, nil
 	}
 	// First part of nested reference fieldPath is the name of top level Spec
 	// field. Ex: For 'ResourcesVpcConfig.SecurityGroupIds' fieldpath the
@@ -587,8 +598,25 @@ func updateTypeDefAttributeWithReference(fieldPath string, tdefs []*TypeDef, crd
 			" inside %s TypeDef to create reference for %s",
 			fieldName, parentFieldTypeDefName, fieldPath))
 	}
+	return parentFieldTypeDef, fieldAttr
+}
 
-	addReferenceAttribute(parentFieldTypeDef, fieldAttr)
+// setTypeDefAttributeGoTag sets the GoTag for the corresponding attribute
+// represented by fieldPath of nested field.
+func setTypeDefAttributeGoTag(crd *CRD, fieldPath string, f *Field, tdefs []*TypeDef) {
+	_, fieldAttr := getAttributeFromPath(crd, fieldPath, tdefs)
+	if fieldAttr != nil {
+		fieldAttr.GoTag = f.GetGoTag()
+	}
+}
+
+// updateTypeDefAttributeWithReference adds a new AWSResourceReference attribute
+// for the corresponding attribute represented by fieldPath of nested field
+func updateTypeDefAttributeWithReference(crd *CRD, fieldPath string, tdefs []*TypeDef) {
+	parentFieldTypeDef, fieldAttr := getAttributeFromPath(crd, fieldPath, tdefs)
+	if fieldAttr != nil && parentFieldTypeDef != nil {
+		addReferenceAttribute(parentFieldTypeDef, fieldAttr)
+	}
 }
 
 // addReferenceAttribute creates a corresponding reference attribute for

templates/apis/type_def.go.tpl

@@ -7,7 +7,7 @@ type {{ .Names.Camel }} struct {
 	{{- if $attr.Shape.Documentation }}
 	{{ $attr.Shape.Documentation }}
 	{{- end }}
-	{{ $attr.Names.Camel }} {{ $attr.GoType }} `json:"{{ $attr.Names.CamelLower }},omitempty"`
+	{{ $attr.Names.Camel }} {{ $attr.GoType }} {{ $attr.GetGoTag }}
 {{- end }}
 }
 {{- end -}}