add nullable hcl string

Author: Emyrk

site/genweb/main.go

@@ -94,10 +94,16 @@ func TypeMappings(gen *guts.GoParser) error {
 				Prefix:  "",
 			})
 		},
+		"github.com/coder/preview/types.HCLString": func() bindings.ExpressionType {
+			return bindings.Reference(bindings.Identifier{
+				Name:    "NullHCLString",
+				Package: nil,
+				Prefix:  "",
+			})
+		},
 	})
 
 	err := gen.IncludeCustom(map[string]string{
-		"github.com/coder/preview/types.HCLString": "string",
 		// Serpent fields should be converted to their primitive types
 		"github.com/coder/serpent.Regexp":         "string",
 		"github.com/coder/serpent.StringArray":    "string",

site/src/types/preview.ts

@@ -15,9 +15,15 @@ export interface FriendlyDiagnostic {
     readonly detail: string;
 }
 
+// From types/value.go
+export interface NullHCLString {
+    readonly value: string;
+    readonly valid: boolean;
+}
+
 // From types/parameter.go
 export interface Parameter extends ParameterData {
-    readonly value: string;
+    readonly value: NullHCLString;
     readonly diagnostics: Diagnostics;
 }
 
@@ -32,7 +38,7 @@ export interface ParameterData {
     // empty interface{} type, falling back to unknown
     readonly form_type_metadata: unknown;
     readonly mutable: boolean;
-    readonly default_value: string;
+    readonly default_value: NullHCLString;
     readonly icon: string;
     readonly options: readonly (ParameterOption)[];
     readonly validations: readonly (ParameterValidation)[];
@@ -45,7 +51,7 @@ export interface ParameterData {
 export interface ParameterOption {
     readonly name: string;
     readonly description: string;
-    readonly value: string;
+    readonly value: NullHCLString;
     readonly icon: string;
 }
 

types/value.go

@@ -9,6 +9,11 @@ import (
 	"github.com/zclconf/go-cty/cty"
 )
 
+type NullHCLString struct {
+	Value string `json:"value"`
+	Valid bool   `json:"valid"`
+}
+
 // @typescript-ignore HCLString
 type HCLString struct {
 	Value cty.Value
@@ -36,16 +41,23 @@ func ToHCLString(block *terraform.Block, attr *terraform.Attribute) HCLString {
 }
 
 func (s HCLString) MarshalJSON() ([]byte, error) {
-	return json.Marshal(s.AsString())
+	return json.Marshal(NullHCLString{
+		Value: s.AsString(),
+		Valid: s.Valid() && s.Value.IsKnown(),
+	})
 }
 
 func (s *HCLString) UnmarshalJSON(data []byte) error {
-	var str string
-	if err := json.Unmarshal(data, &str); err != nil {
+	var reduced NullHCLString
+	if err := json.Unmarshal(data, &reduced); err != nil {
 		return err
 	}
+	if reduced.Valid {
+		*s = StringLiteral(reduced.Value)
+	} else {
+		s.Value = cty.NilVal
+	}
 
-	*s = StringLiteral(str)
 	return nil
 }