chore: simplify null union elements

Emyrk · Emyrk · commit 139809366a22 · 2025-02-27T15:18:02.000-06:00
not a perfect solution, might require an ast walker that
can replace nodes to get it working perfectly
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
diff --git a/bindings/bindings.go b/bindings/bindings.go
@@ -395,7 +395,7 @@ func (b *Bindings) Union(ty *UnionType) (*goja.Object, error) {
 		return nil, err
 	}
 
-	var types []interface{}
+	var types []any
 	for _, t := range ty.Types {
 		v, err := b.ToTypescriptExpressionNode(t)
 		if err != nil {
diff --git a/config/mutations.go b/config/mutations.go
@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"log/slog"
 	"reflect"
+	"slices"
 	"strings"
 
 	"github.com/coder/guts"
@@ -223,3 +224,48 @@ func (h *hasAnyVisitor) Visit(node bindings.Node) walk.Visitor {
 	}
 	return h
 }
+
+// NullUnionSlices converts slices with nullable elements to remove the 'null'
+// type from the union.
+// This happens when a golang pointer is the element type of a slice.
+// Example:
+// GolangType: []*string
+// TsType: (string | null)[] --> (string)[]
+// TODO: Somehow remove the parenthesis from the output type.
+// Might have to change the node from a union type to it's first element.
+func NullUnionSlices(ts *guts.Typescript) {
+	ts.ForEach(func(key string, node bindings.Node) {
+		walk.Walk(&nullUnionVisitor{}, node)
+	})
+}
+
+type nullUnionVisitor struct{}
+
+func (v *nullUnionVisitor) Visit(node bindings.Node) walk.Visitor {
+	if array, ok := node.(*bindings.ArrayType); ok {
+		// Is array
+		if union, ok := array.Node.(*bindings.UnionType); ok {
+			hasNull := slices.ContainsFunc(union.Types, func(t bindings.ExpressionType) bool {
+				_, isNull := t.(*bindings.Null)
+				return isNull
+			})
+
+			// With union type
+			if len(union.Types) == 2 && hasNull {
+				// A union of 2 types, one being null
+				// Remove the null type
+				newTypes := make([]bindings.ExpressionType, 0, 1)
+				for _, t := range union.Types {
+					if _, isNull := t.(*bindings.Null); isNull {
+						continue
+					}
+					newTypes = append(newTypes, t)
+				}
+				union.Types = newTypes
+
+			}
+		}
+	}
+
+	return v
+}
diff --git a/convert_test.go b/convert_test.go
@@ -96,6 +96,7 @@ func TestGeneration(t *testing.T) {
 				config.EnumLists,
 				config.ExportTypes,
 				config.ReadOnly,
+				config.NullUnionSlices,
 			)
 
 			output, err := ts.Serialize()
diff --git a/testdata/nullable/nullable.go b/testdata/nullable/nullable.go
@@ -7,6 +7,7 @@ type NullableFields struct {
 	Nullable          *string      `json:"nullable"`
 	NullableOmitEmpty *string      `json:"nullableOmitEmpty,omitempty"`
 	NullTime          sql.NullTime `json:"nullTime"`
+	SlicePointer      []*string    `json:"slicePointer"`
 }
 
 type EmptyFields struct {
diff --git a/testdata/nullable/nullable.ts b/testdata/nullable/nullable.ts
@@ -12,4 +12,5 @@ export interface NullableFields {
     readonly nullable: string | null;
     readonly nullableOmitEmpty?: string | null;
     readonly nullTime: string | null;
+    readonly slicePointer: readonly (string)[];
 }

Original file line number	Diff line number	Diff line change
`@@ -395,7 +395,7 @@ func (b Bindings) Union(ty UnionType) (*goja.Object, error) {`
`395`	`395`	`return nil, err`
`396`	`396`	`}`
`397`	`397`
`398`		`- var types []interface{}`
	`398`	`+ var types []any`
`399`	`399`	`for _, t := range ty.Types {`
`400`	`400`	`v, err := b.ToTypescriptExpressionNode(t)`
`401`	`401`	`if err != nil {`
Original file line number	Diff line number	Diff line change
`@@ -96,6 +96,7 @@ func TestGeneration(t *testing.T) {`
`96`	`96`	`config.EnumLists,`
`97`	`97`	`config.ExportTypes,`
`98`	`98`	`config.ReadOnly,`
	`99`	`+ config.NullUnionSlices,`
`99`	`100`	`)`
`100`	`101`
`101`	`102`	`output, err := ts.Serialize()`
Original file line number	Diff line number	Diff line change
`@@ -7,6 +7,7 @@ type NullableFields struct {`
`7`	`7`	Nullable *string `json:"nullable"`
`8`	`8`	NullableOmitEmpty *string `json:"nullableOmitEmpty,omitempty"`
`9`	`9`	NullTime sql.NullTime `json:"nullTime"`
	`10`	+ SlicePointer []*string `json:"slicePointer"`
`10`	`11`	`}`
`11`	`12`
`12`	`13`	`type EmptyFields struct {`
Original file line number	Diff line number	Diff line change
`@@ -12,4 +12,5 @@ export interface NullableFields {`
`12`	`12`	`readonly nullable: string \| null;`
`13`	`13`	`readonly nullableOmitEmpty?: string \| null;`
`14`	`14`	`readonly nullTime: string \| null;`
	`15`	`+ readonly slicePointer: readonly (string)[];`
`15`	`16`	`}`