How to Transform Snake Case to Camel Case in TypeScript?

When working with APIs, we often encounter data in formats that do not match our application's preferred coding style. For instance, if you're using TypeScript and Vue.js, you might receive data in snake_case from an API but prefer to work with camelCase throughout your application. The good news is that you can easily transform this data without losing type safety. Let's delve into how you can achieve that with the help of interfaces and utility types in TypeScript.

Understanding the Problem

When you define an interface such as MergedReviewDetails, you structure your data according to your application's needs. An example of this could be:

export interface MergedReviewDetails {

  parentReview: Mmcid;

  childReviews: Mmcid[];

}

However, the API might return data with properties in snake_case:

{

  "parent_review": "1234",

  "child_reviews": ["5678", "91011"]

}

This discrepancy can create confusion and reduce code readability in your Vue.js project. To enhance maintainability, it's crucial that your data reflects the coding standards you're following while still binding seamlessly to the original API response.

Binding Snake Case to Camel Case

To solve this issue, TypeScript allows you to create transformation functions that change property names while maintaining type safety. Here’s how you can do this step-by-step:

Step 1: Define Your Interfaces

You already have two different interfaces: one for the API response in snake_case and another for your application in camelCase. Let's define an interface for the snake_case data:

export interface ApiMergedReviewDetails {

  parent_review: Mmcid;

  child_reviews: Mmcid[];

}

Step 2: Create a Transformation Function

Now, you need a function to convert your API response to your application's preferred format. This function will take an ApiMergedReviewDetails object and return a MergedReviewDetails object:

function transformApiToMergedReviewDetails(apiData: ApiMergedReviewDetails): MergedReviewDetails {

  return {

    parentReview: apiData.parent_review,

    childReviews: apiData.child_reviews

  };

}

Step 3: Using the Transformation in Your Vue.js Component

When you call your API, you'll receive the data in snake_case and can apply your transformation function:

import axios from 'axios';



async function fetchAndTransformReviewDetails() {

  const response = await axios.get('/api/reviews');

  const apiData: ApiMergedReviewDetails = response.data;

  const mergedReviewDetails: MergedReviewDetails = transformApiToMergedReviewDetails(apiData);

  return mergedReviewDetails;

}

This way, you keep your code clean, adhere to your coding standards, and allow for easy maintenance and adjustments in the future.

Step 4: Example Usage in a Vue.js Component

Here’s an example of how you might use this transformation function within a Vue.js component:

<template>

  <div>

    <h1>Reviews</h1>

    <ul v-if="reviews">

      <li v-for="review in reviews.childReviews" :key="review">

        {{ review }}

      </li>

    </ul>

  </div>

</template>



<script lang="ts">

import { defineComponent, ref, onMounted } from 'vue';

import { MergedReviewDetails, transformApiToMergedReviewDetails, ApiMergedReviewDetails } from './your-types';

import axios from 'axios';



export default defineComponent({

  setup() {

    const reviews = ref<MergedReviewDetails | null>(null);



    onMounted(async () => {

      const response = await axios.get('/api/reviews');

      const apiData: ApiMergedReviewDetails = response.data;

      reviews.value = transformApiToMergedReviewDetails(apiData);

    });



    return { reviews };

  }

});

</script>

Frequently Asked Questions

Can I use TypeScript's mapped types for transformation?

Yes, you can leverage mapped types to create more reusable transformations if you have multiple fields to transform. Consider using utility types to map properties.

Is there a library for transforming case automatically?

Yes, libraries like change-case provide utilities to convert strings between different casing styles, which can be helpful in different contexts.

Conclusion

Transforming snake_case API responses to camelCase in TypeScript can be elegantly handled with interface definitions and a simple transformation function. This approach maintains type safety, ensures readability, and keeps your Vue.js application cohesive with your coding standards. By following these steps, you can seamlessly bind your API data to your application's needs while rewriting the keys as desired.