TanStack Form supports arrays as values in a form, including sub-object values inside of an array.
To use an array, you can use field.state.value on an array value:
function App() {
const form = useForm({
defaultValues: {
people: [],
},
})
return (
<form.Field name="people" mode="array">
{(field) => (
<div>
{field.state.value.map((_, i) => {
// ...
})}
</div>
)}
</form.Field>
)
}
function App() {
const form = useForm({
defaultValues: {
people: [],
},
})
return (
<form.Field name="people" mode="array">
{(field) => (
<div>
{field.state.value.map((_, i) => {
// ...
})}
</div>
)}
</form.Field>
)
}
This will generate the mapped JSX every time you run pushValue on field:
<button onClick={() => field.pushValue({ name: '', age: 0 })} type="button">
Add person
</button>
<button onClick={() => field.pushValue({ name: '', age: 0 })} type="button">
Add person
</button>
Finally, you can use a subfield like so:
<form.Field key={i} name={`people[${i}].name`}>
{(subField) => (
<input
value={subField.state.value}
onChange={(e) => subField.handleChange(e.target.value)}
/>
)}
</form.Field>
<form.Field key={i} name={`people[${i}].name`}>
{(subField) => (
<input
value={subField.state.value}
onChange={(e) => subField.handleChange(e.target.value)}
/>
)}
</form.Field>
function App() {
const form = useForm({
defaultValues: {
people: [],
},
onSubmit({ value }) {
alert(JSON.stringify(value))
},
})
return (
<div>
<form
onSubmit={(e) => {
e.preventDefault()
e.stopPropagation()
form.handleSubmit()
}}
>
<form.Field name="people" mode="array">
{(field) => {
return (
<div>
{field.state.value.map((_, i) => {
return (
<form.Field key={i} name={`people[${i}].name`}>
{(subField) => {
return (
<div>
<label>
<div>Name for person {i}</div>
<input
value={subField.state.value}
onChange={(e) =>
subField.handleChange(e.target.value)
}
/>
</label>
</div>
)
}}
</form.Field>
)
})}
<button
onClick={() => field.pushValue({ name: '', age: 0 })}
type="button"
>
Add person
</button>
</div>
)
}}
</form.Field>
<form.Subscribe
selector={(state) => [state.canSubmit, state.isSubmitting]}
children={([canSubmit, isSubmitting]) => (
<button type="submit" disabled={!canSubmit}>
{isSubmitting ? '...' : 'Submit'}
</button>
)}
/>
</form>
</div>
)
}
function App() {
const form = useForm({
defaultValues: {
people: [],
},
onSubmit({ value }) {
alert(JSON.stringify(value))
},
})
return (
<div>
<form
onSubmit={(e) => {
e.preventDefault()
e.stopPropagation()
form.handleSubmit()
}}
>
<form.Field name="people" mode="array">
{(field) => {
return (
<div>
{field.state.value.map((_, i) => {
return (
<form.Field key={i} name={`people[${i}].name`}>
{(subField) => {
return (
<div>
<label>
<div>Name for person {i}</div>
<input
value={subField.state.value}
onChange={(e) =>
subField.handleChange(e.target.value)
}
/>
</label>
</div>
)
}}
</form.Field>
)
})}
<button
onClick={() => field.pushValue({ name: '', age: 0 })}
type="button"
>
Add person
</button>
</div>
)
}}
</form.Field>
<form.Subscribe
selector={(state) => [state.canSubmit, state.isSubmitting]}
children={([canSubmit, isSubmitting]) => (
<button type="submit" disabled={!canSubmit}>
{isSubmitting ? '...' : 'Submit'}
</button>
)}
/>
</form>
</div>
)
}
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