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fix(select): add empty string as option when not required #40

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Merged
Dominik Kadera (dominikkadera) merged 4 commits into from
Mar 9, 2026
Merged

fix(select): add empty string as option when not required #40

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45643b1
fix(select): add empty string as option when not required
dominikkadera Mar 6, 2026
6a85722
Merge branch 'main' into fix-select-empty
dominikkadera Mar 6, 2026
261a54e
chore: pr review
dominikkadera Mar 6, 2026
2f195cd
build(deps): package update
dominikkadera Mar 6, 2026
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22 changes: 18 additions & 4 deletions src/forman.ts
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Original file line number Diff line number Diff line change
@@ -1,4 +1,7 @@
import type { JSONSchema7, JSONSchema7Definition, JSONSchema7TypeName } from 'json-schema';

/** Description applied to non-required select-like fields that accept an empty value. */
export const EMPTY_OPTION_DESCRIPTION = 'Optional field, can be left empty.';
import type {
FormanSchemaField,
FormanSchemaValue,
Expand Down Expand Up @@ -567,17 +570,15 @@ function handleSelectOrPathType(
return optionOrGroup as FormanSchemaOption;
});

// For non-required selects with placeholder.nested, inject placeholder as an artificial null-value option.
// null is used (not undefined) because it's a valid JSON Schema const value and FormanSchemaValue.
// For non-required selects with placeholder.nested, inject placeholder as an artificial empty-string option.
if (field.type === 'select' && !field.required && isObject<FormanSchemaExtendedOptions>(field.options)) {
const placeholder = field.options.placeholder;
if (isObject<{ label: string; nested?: FormanSchemaNested }>(placeholder) && placeholder.nested) {
(options ||= []).push({
value: null,
value: '',
label: placeholder.label,
nested: placeholder.nested,
});
result.type = [result.type as JSONSchema7TypeName, 'null'];
}
}

Expand Down Expand Up @@ -651,6 +652,19 @@ function handleSelectOrPathType(
}
}

// For non-required select-like fields, prepend '' as a valid "no selection" option and set default.
if (!field.required) {
if (result.enum && !result.enum.includes('')) {
result.enum = ['', ...result.enum];
} else if (result.oneOf && !result.oneOf.some((entry): entry is JSONSchema7 => isObject(entry) && entry.const === '')) {
result.oneOf = [{ title: 'Empty', const: '' }, ...result.oneOf];
}
result.default = '';
if (!result.description) {
result.description = EMPTY_OPTION_DESCRIPTION;
}
}

result = handleNestedWithDomain(field, nested, domain, result, context);

if (field.rpc) result = processRpcDirective(field, result, context);
Expand Down
18 changes: 12 additions & 6 deletions src/json.ts
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
import type { JSONSchema7 } from 'json-schema';
import { noEmpty, isObject } from './utils';
import type { FormanSchemaField, FormanSchemaFieldType, FormanSchemaValue } from './types';
import { EMPTY_OPTION_DESCRIPTION } from './forman';
import { udttypeCollapse } from './composites/udttype';
import { udtspecCollapse } from './composites/udtspec';

Expand Down Expand Up @@ -102,10 +103,11 @@ export function toFormanSchema(field: JSONSchema7): FormanSchemaField {
// If the field is flagged as path selector field root, then short-circuit to it
const pathInfo = Object.getOwnPropertyDescriptor(field, 'x-path');
if (pathInfo) {
const help = field.description === EMPTY_OPTION_DESCRIPTION ? undefined : noEmpty(field.description);
return {
type: pathInfo.value.type,
label: noEmpty(field.title),
help: noEmpty(field.description),
help,
options: {
store: Object.getOwnPropertyDescriptor(field, 'x-fetch')?.value,
showRoot: pathInfo.value.showRoot,
Expand All @@ -115,20 +117,24 @@ export function toFormanSchema(field: JSONSchema7): FormanSchemaField {
}
if (field.enum) {
// For strings with enum, create a select type
const help = field.description === EMPTY_OPTION_DESCRIPTION ? undefined : noEmpty(field.description);
return {
type: 'select',
label: noEmpty(field.title),
help: noEmpty(field.description),
options: field.enum.map(value => ({ value: value as FormanSchemaValue })),
help,
options: field.enum
.filter(value => value !== '')
.map(value => ({ value: value as FormanSchemaValue })),
};
} else if (field.oneOf) {
// For strings with enum, create a select type
// For strings with oneOf, create a select type
const help = field.description === EMPTY_OPTION_DESCRIPTION ? undefined : noEmpty(field.description);
return {
type: 'select',
label: noEmpty(field.title),
help: noEmpty(field.description),
help,
options: field.oneOf
.filter(value => value)
.filter(value => value && (value as JSONSchema7).const !== '')
.map(value => ({ value: (value as JSONSchema7).const as FormanSchemaValue })),
};
}
Expand Down
8 changes: 4 additions & 4 deletions src/validator.ts
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Expand Up @@ -306,8 +306,8 @@ async function validateFormanValue(
};
}

if (value == null) {
// When a select field has placeholder.nested, null means "no selection" and we need to validate the nested fields
if (value == null || value === '') {
// When a select field has placeholder.nested, null/'' means "no selection" and we need to validate the nested fields
if (normalizedField.type === 'select' && hasPlaceholderNested(normalizedField)) {
return handleSelectType(value, normalizedField, context);
}
Expand Down Expand Up @@ -908,8 +908,8 @@ async function handleSelectType(
});
}
}
} else if (value == null && hasPlaceholderNested(field)) {
// Null value with placeholder.nested: treat as valid "no selection" and use placeholder's nested
} else if ((value == null || value === '') && hasPlaceholderNested(field)) {
// Null/empty value with placeholder.nested: treat as valid "no selection" and use placeholder's nested
const placeholder = (field.options as FormanSchemaExtendedOptions).placeholder as {
label: string;
nested?: FormanSchemaNested;
Expand Down
5 changes: 5 additions & 0 deletions test/composites/__snapshots__/udttype.spec.ts.snap
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Original file line number Diff line number Diff line change
Expand Up @@ -281,7 +281,12 @@ exports[`udttype composite Forman -> JSON Schema should convert schema with udtt
"x-composite": "udtspec",
},
"udttype": {
"default": "",
"oneOf": [
{
"const": "",
"title": "Empty",
},
{
"const": "array",
"title": "Array",
Expand Down
5 changes: 3 additions & 2 deletions test/composites/udttype.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -36,10 +36,11 @@ describe('udttype composite', () => {
expect(udttypeDef.type).toBe('string');
expect(udttypeDef.title).toBeUndefined();
expect(udttypeDef.oneOf).toBeDefined();
expect(udttypeDef.oneOf!.length).toBe(7);
expect(udttypeDef.oneOf!.length).toBe(8);
expect(udttypeDef.default).toBe('');

const optionValues = udttypeDef.oneOf!.map(o => (o as JSONSchema7).const);
expect(optionValues).toEqual(['array', 'collection', 'date', 'text', 'number', 'boolean', 'buffer']);
expect(optionValues).toEqual(['', 'array', 'collection', 'date', 'text', 'number', 'boolean', 'buffer']);
});

it('should produce conditional nested fields via allOf on parent', () => {
Expand Down
24 changes: 24 additions & 0 deletions test/directives/grouped.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -88,7 +88,13 @@ describe('Grouped', () => {
expect(jsonSchema).toEqual({
properties: {
groupedSelect: {
default: '',
description: 'Optional field, can be left empty.',
oneOf: [
{
const: '',
title: 'Empty',
},
{
const: 'alpha',
title: 'Phonetic: Alpha',
Expand All @@ -110,7 +116,13 @@ describe('Grouped', () => {
type: 'string',
},
partiallyGroupedSelect: {
default: '',
description: 'Optional field, can be left empty.',
oneOf: [
{
const: '',
title: 'Empty',
},
{
const: 'alpha',
title: 'Alpha',
Expand All @@ -132,7 +144,13 @@ describe('Grouped', () => {
type: 'string',
},
select: {
default: '',
description: 'Optional field, can be left empty.',
oneOf: [
{
const: '',
title: 'Empty',
},
{
const: 'alpha',
title: 'Alpha',
Expand All @@ -146,7 +164,13 @@ describe('Grouped', () => {
type: 'string',
},
wronglyPartiallyGroupedSelect: {
default: '',
description: 'Optional field, can be left empty.',
oneOf: [
{
const: '',
title: 'Empty',
},
{
const: 'alpha',
title: 'Alpha',
Expand Down
8 changes: 8 additions & 0 deletions test/directives/nested.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -52,6 +52,8 @@ describe('Nested', () => {
nestedSelect: {
title: 'Nested Select',
type: 'string',
default: '',
description: 'Optional field, can be left empty.',
'x-fetch': 'rpc://dropdownExplorer',
'x-nested': {
$ref: 'rpc://renderFields?nestedSelect={{nestedSelect}}',
Expand Down Expand Up @@ -408,7 +410,10 @@ describe('Nested', () => {
booleanSelect: {
title: 'Boolean Select',
type: 'string',
default: '',
description: 'Optional field, can be left empty.',
oneOf: [
{ title: 'Empty', const: '' },
{ title: 'TRUE', const: true },
{ title: 'FALSE', const: false },
],
Expand All @@ -419,7 +424,10 @@ describe('Nested', () => {
mergedSelect: {
title: 'Merged Select',
type: 'string',
default: '',
description: 'Optional field, can be left empty.',
oneOf: [
{ title: 'Empty', const: '' },
{ title: 'TRUE', const: true },
{ title: 'FALSE', const: false },
],
Expand Down
8 changes: 8 additions & 0 deletions test/directives/rpc.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -82,6 +82,8 @@ describe('RPC', () => {
select: {
title: 'Select',
type: 'string',
default: '',
description: 'Optional field, can be left empty.',
'x-fetch': 'rpc://searchEntries?parent={{parent}}',
'x-search': {
inputSchema: {
Expand Down Expand Up @@ -134,7 +136,13 @@ describe('RPC', () => {
],
properties: {
parent: {
default: '',
description: 'Optional field, can be left empty.',
oneOf: [
{
const: '',
title: 'Empty',
},
{
const: 'show',
title: 'Show',
Expand Down
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