How do I update initialValues with values from props/api request?
  • 08-May-2023
Lightrun Team
Author Lightrun Team
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How do I update initialValues with values from props/api request?

How do I update initialValues with values from props/api request?

Lightrun Team
Lightrun Team
08-May-2023

Explanation of the problem

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When adding a new entry in a form using Formik, the initialValues property is set to empty strings by default. However, in cases where the user needs to edit the values of an existing entry, it is necessary to replace the initialValues with data obtained from a REST API GET request. This can be achieved using the useEffect hook and setValues method provided by Formik.

Firstly, the useEffect hook can be used to fetch the data from the REST API and update the form values once the component has mounted. In the following code block, we define a function fetchData that uses the fetch API to retrieve the data from the API endpoint. The setValues method is then used to set the values of the form based on the retrieved data.

import { useState, useEffect } from 'react';
import { Formik, Form, Field } from 'formik';

const MyForm = () => {
  const [data, setData] = useState(null);

  useEffect(() => {
    const fetchData = async () => {
      const response = await fetch('/api/my-data');
      const json = await response.json();
      setData(json);
    };
    fetchData();
  }, []);

  return (
    <Formik
      initialValues={{ name: '', email: '' }}
      onSubmit={(values) => console.log(values)}
    >
      {({ setValues }) => (
        <Form>
          <Field name="name" value={data ? data.name : ''} />
          <Field name="email" value={data ? data.email : ''} />
          <button
            type="button"
            onClick={() => setValues({ name: data.name, email: data.email })}
          >
            Load Data
          </button>
          <button type="submit">Submit</button>
        </Form>
      )}
    </Formik>
  );
};

In the above code block, we use the useState hook to store the fetched data in the data variable. We then use the useEffect hook to fetch the data and update the data variable once the component has mounted. In the Formik component, we use the setValues method to set the form values to the fetched data when the “Load Data” button is clicked.

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Problem solution for How do I update initialValues with values from props/api request?

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To initialize the form values of a Formik form with data from a REST API, there are a few different ways to do it. One approach is to use the useMemo hook to fetch the data and store it in a variable outside of the useFormik hook. This can help prevent the data from being re-fetched on every render, and can be used in conjunction with the enableReinitialize property of the useFormik hook to allow the form values to be updated with the new data.

Another approach is to use the enableReinitialize property directly. This will allow Formik to automatically update the form values whenever the initialValues prop changes, without needing to manually update them. However, this property can also reset some other form state like isDirty and touched fields, so it’s important to be aware of this potential behavior.

Overall, the approach to initializing Formik form values with data from a REST API will depend on the specific use case and requirements of the project. Both the useMemo and enableReinitialize approaches can be useful, and it’s important to consider the trade-offs and limitations of each method. Additionally, it may be necessary to handle errors and edge cases related to fetching data from the API, such as network failures or unexpected response formats.

 

Other popular problems with jaredpalmer formik

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Problem: Complex nested object handling

One of the most common problems with using Formik by Jared Palmer is handling complex nested objects. It can be difficult to properly map the fields of a deeply nested object to the corresponding form inputs, leading to issues with data binding and validation.

Solution:

To solve this problem, it is important to use a set of helper functions or libraries that can make it easier to handle nested objects in Formik. One such library is formik-nested which provides a set of utility functions that make it easy to handle nested fields in Formik. Additionally, you can create your custom utility functions that can help you to handle nested objects, for instance, a function that flattens the object, making it easier to map to the form fields.

Code snippet for flattening the object:

import _ from 'lodash';

function flattenObject(object) {
  return _.reduce(
    object,
    (acc, value, key) => {
      if (_.isPlainObject(value)) {
        _.assign(acc, flattenObject(value));
      } else {
        acc[key] = value;
      }
      return acc;
    },
    {}
  );
}

Problem: Handling multiple forms on a single page

Another common problem with using Formik by Jared Palmer is handling multiple forms on a single page. It can be difficult to manage the state of multiple forms and ensure that data is properly bound to the correct form inputs.

Solution:

To solve this problem, it is important to use a unique key for each form instance. This can be done by using the key prop provided by Formik or by using a custom hook that creates a unique key for each form instance. Additionally, it’s useful to wrap each form in a separate component and manage their state separately. This allows you to have a better control over the different forms and avoid conflicts between them.

Code snippet for wrapping each form in a separate component:

import { useState } from 'react';

function Form1() {
  const [formState, setFormState] = useState({});
  return (
    <Formik
      initialValues={formState}
      onSubmit={(values) => setFormState(values)}
    >
      {/* form fields */}
    </Formik>
  );
}

function Form2() {
  const [formState, setFormState] = useState({});
  return (
    <Formik
      initialValues={formState}
      onSubmit={(values) => setFormState(values)}
    >
      {/* form fields */}
    </Formik>
  );
}

Problem: Error handling and validation

Another common problem with using Formik by Jared Palmer is handling error messages and validation. It can be difficult to properly display error messages and validate form input in a way that is both user-friendly and effective.

Solution:

To solve this problem, it is important to use a comprehensive validation library such as Yup or Joi that provides a range of validation methods and error handling. Additionally, it’s useful to make use of the errors object provided by Formik to display error messages next to the appropriate form fields. This allows you to give clear and specific feedback to the user when an error occurs.

Code snippet for validating the form fields using Yup:

import * as Yup from 'yup';

A brief introduction to jaredpalmer formik

­

Formik by Jared Palmer is a popular library for building forms in React. It provides a powerful set of tools for handling form state, validation, and submission, making it easy to create complex forms with minimal code. Formik provides a high-level abstraction that allows developers to manage the state of their forms, including the values of form fields, validation states, and error messages. Additionally, Formik provides a set of built-in validation methods and allows for custom validation as well.

One of the key features of Formik is its ability to handle form state management. Formik provides a set of hooks and components that make it easy to manage the state of a form, including the values of form fields, validation states, and error messages. Formik also provides a set of built-in validation methods, including support for Yup, a popular validation library for JavaScript. Additionally, Formik allows for custom validation methods to be defined, giving developers full control over the validation process. Formik also provides a set of hooks and components that make it easy to handle form submission, including support for asynchronous submissions, and provide feedback to the user.

Most popular applications of jaredpalmer formik include

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  1. Form management: One of the primary uses of Formik is to manage forms. It provides a set of methods and props that make it easy to handle form submissions, form field updates, and form validation. Formik also makes it easy to keep track of form state and display errors to the user.
  2. Simplifying form logic: Formik simplifies form logic by abstracting away the complexities of handling form field updates and validation. This allows developers to focus on the business logic and user experience of their forms without having to worry about the underlying implementation.
  3. Integrating with other libraries: Formik can be easily integrated with other libraries such as Yup for form validation and React Router for navigation. This allows developers to leverage the benefits of Formik with other libraries they are already using, making it easy to add forms to existing applications.
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