feat: enhance OmegaForm with default value extraction for tagged unions

Author: jfet97

packages/vue-components/src/components/OmegaForm/OmegaTaggedUnionInternal.vue

@@ -19,6 +19,7 @@ import { type DeepKeys, type DeepValue } from "@tanstack/vue-form"
 import { S } from "effect-app"
 import { watch } from "vue"
 import { getTransformationFrom } from "../../utils"
+import { extractSchemaDefaults } from "./defaultAST"
 import { type OmegaFieldInternalApi } from "./InputProps"
 import { type useOmegaForm } from "./useOmegaForm"
 
@@ -37,20 +38,51 @@ watch(() => props.state, (newTag, oldTag) => {
   if (newTag === null) {
     props.field.setValue(null as DeepValue<From, Name>)
   }
+
+  props.form.reset(values.value)
+
   if (newTag !== oldTag) {
+    // get default values from AST for the new tag (only for root level tagged unions)
     if (props.name === void 0 && S.AST.isUnion(props.form._schema.ast)) {
-      const members = props
+      const indexOfSelectedMember = props
         .form
         ._schema
         .ast
         .types
-        .map((t) => getTransformationFrom(t))
-        .filter((t) => S.AST.isTypeLiteral(t) || S.AST.isTransformation(t))
-        .map((t) => t.propertySignatures)
-      console.log("members", members)
+        .map((t, i) => ({ original: i, unwrapped: getTransformationFrom(t) }))
+        .flatMap((x) =>
+          S.AST.isTypeLiteral(x.unwrapped) || S.AST.isTransformation(x.unwrapped)
+            ? x
+                .unwrapped
+                .propertySignatures
+                .filter((ps) => S.AST.isLiteral(ps.type) && ps.type.literal === newTag)
+                .length > 0
+              ? [x.original]
+              : []
+            : []
+        )[0]
+
+      // even if the type doesn't say so, indexOfSelectedMember may be undefined
+      if (
+        indexOfSelectedMember != void 0
+        && "members" in props.form._schema
+        && Array.isArray(props.form._schema.members)
+      ) {
+        const defaultsOfSelectedMember = Object.assign(
+          extractSchemaDefaults(
+            props
+              .form
+              ._schema
+              .members[indexOfSelectedMember],
+            values.value
+          ),
+          { _tag: newTag }
+        )
+
+        props.form.reset(defaultsOfSelectedMember)
+      }
     }
-    console.log("resetting form", values.value)
-    props.form.reset(values.value)
+
     setTimeout(() => {
       props.field.validate("change")
     }, 0)

packages/vue-components/src/components/OmegaForm/defaultAST.ts

@@ -122,7 +122,7 @@ const partialRecursive = <A, I, R>(schema: S.Schema<A, I, R>): S.Schema<Partial<
 }
 
 // Helper function to recursively extract default values from schema AST swag ast
-const extractDefaultsFromAST = (schemaObj: any): any => {
+export const extractDefaultsFromAST = (schemaObj: any): any => {
   const result: Record<string, any> = {}
 
   // Check if this schema has fields (struct)

packages/vue-components/stories/OmegaForm/RootLevelTaggedUnion.vue

@@ -74,8 +74,7 @@ import { useOmegaForm } from "../../src"
 // Root-level union schema - the entire form is a union
 const schema = S.Union(
   S.Struct({
-    a: S.NonEmptyString255,
-    first: S.PositiveNumber.pipe(S.withDefaultConstructor(() => S.PositiveNumber(200))),
+    a: S.NonEmptyString255.pipe(S.withDefaultConstructor(() => S.NonEmptyString255("aaaa"))),
     common: S.String,
     _tag: S.Literal("A")
   }),