72 lines
2.2 KiB
Markdown
72 lines
2.2 KiB
Markdown
# Form >> Use Cases ||20
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```js script
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import { html } from '@mdjs/mdjs-preview';
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import { Required } from '@lion/ui/form-core.js';
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import { loadDefaultFeedbackMessages } from '@lion/ui/validate-messages.js';
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import '@lion/ui/define/lion-input.js';
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import '@lion/ui/define/lion-form.js';
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```
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## Submit & Reset
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To submit a form, use a regular button (or `LionButtonSubmit`) somewhere inside the native `<form>`.
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Then, add a `submit` handler on the `lion-form`.
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You can use this event to do your own (pre-)submit logic, like getting the serialized form data and sending it to a backend API.
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Another example is checking if the form has errors, and focusing the first field with an error.
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To fire a submit from JavaScript, select the `lion-form` element and call `.submit()`.
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```js preview-story
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export const formSubmit = () => {
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loadDefaultFeedbackMessages();
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const submitHandler = ev => {
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if (ev.target.hasFeedbackFor.includes('error')) {
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const firstFormElWithError = ev.target.formElements.find(el =>
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el.hasFeedbackFor.includes('error'),
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);
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firstFormElWithError.focus();
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return;
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}
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const formData = ev.target.serializedValue;
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fetch('/api/foo/', {
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method: 'POST',
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body: JSON.stringify(formData),
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});
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};
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const submitViaJS = ev => {
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// Call submit on the lion-form element, in your own code you should use
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// a selector that's not dependent on DOM structure like this one.
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ev.target.previousElementSibling.submit();
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};
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return html`
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<lion-form @submit=${submitHandler}>
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<form @submit=${ev => ev.preventDefault()}>
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<lion-input
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name="first_name"
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label="First Name"
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.validators="${[new Required()]}"
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></lion-input>
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<lion-input
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name="last_name"
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label="Last Name"
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.validators="${[new Required()]}"
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></lion-input>
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<div style="display:flex">
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<button>Submit</button>
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<button
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type="button"
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@click=${ev => ev.currentTarget.parentElement.parentElement.parentElement.resetGroup()}
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>
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Reset
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</button>
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</div>
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</form>
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</lion-form>
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<button @click=${submitViaJS}>Explicit submit via JavaScript</button>
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`;
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};
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```
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