Set Size Validation (SizeAtLeast / SizeAtMost / SizeBetween)

[bflad]

Terraform CLI and Framework Versions

Any Terraform CLI version; terraform-plugin-framework v0.8.0

Use Cases or Problem Statement

Provider developers should be able to generically validate types.Set values for their element count (size). For example:

• Whether a known value is equal or more than a certain number of elements, but not constrained
• Whether a known value is equal or less than a certain number of elements, but not constrained
• Whether a value is equal or more than a certain number of elements and equal or less than another number of elements

Proposal

Inside a setvalidator package, create three new unexported types that satisfy the tfsdk.AttributeValidator interface:

var _ sizeAtLeastValidator = tfsdk.AttributeValidator

type sizeAtLeastValidator struct {
  min int
}

func (v sizeAtLeastValidator) Description(ctx context.Context) string {/*...*/}
func (v sizeAtLeastValidator) MarkdownDescription(ctx context.Context) string {/*...*/}
func (v sizeAtLeastValidator) Validate(ctx context.Context, req tfsdk.ValidateAttributeRequest, resp *tfsdk.ValidateAttributeResponse) {/*...*/}

var _ sizeAtMostValidator = tfsdk.AttributeValidator

type sizeAtMostValidator struct {
  max int
}

func (v sizeAtMostValidator) Description(ctx context.Context) string {/*...*/}
func (v sizeAtMostValidator) MarkdownDescription(ctx context.Context) string {/*...*/}
func (v sizeAtMostValidator) Validate(ctx context.Context, req tfsdk.ValidateAttributeRequest, resp *tfsdk.ValidateAttributeResponse) {/*...*/}

var _ sizeBetweenValidator = tfsdk.AttributeValidator

type sizeBetweenValidator struct {
  max int
  min int
}

func (v sizeBetweenValidator) Description(ctx context.Context) string {/*...*/}
func (v sizeBetweenValidator) MarkdownDescription(ctx context.Context) string {/*...*/}
func (v sizeBetweenValidator) Validate(ctx context.Context, req tfsdk.ValidateAttributeRequest, resp *tfsdk.ValidateAttributeResponse) {/*...*/}

Then, create exported functions that return these:

func SizeAtLeast(min int) AttributeValidator {/*...*/}
func SizeAtMost(max int) AttributeValidator {/*...*/}
func SizeBetween(min int, max int) AttributeValidator {/*...*/}

This would allow provider developers to declare attributes such as:

tfsdk.Attribute{
  // ... other fields ...
  Type: types.List{
    ElemType: types.String,
  },
  Validators: tfsdk.AttributeValidators{
    setvalidator.SizeAtLeast(123),
  },
},

Additional Information

No response

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