Normalizing Heterogeneous API Responses with Data Transformation in JavaScript

/**
 * Simulates an API response from a 'users' service with a specific structure.
 */
const userApiResponse = {
  status: 'success',
  data: {
    id: 'usr_101',
    username: 'jsmith',
    emailAddress: '[email protected]',
    creationDate: '2023-01-15T10:30:00Z',
    isActiveUser: true,
    addressInfo: {
      street: '123 Main St',
      city: 'Anytown',
      zip: '12345'
    }
  }
};

/**
 * Simulates an API response from a 'profiles' service with a different structure.
 */
const profileApiResponse = {
  code: 200,
  result: {
    profileId: 'prof_202',
    userIdRef: 'usr_101',
    displayName: 'Johnny S.',
    contactEmail: '[email protected]',
    registrationTimestamp: 1673775600000, // Unix timestamp in ms
    status: 'active'
  }
};

/**
 * Defines the desired standardized data model for a 'User' in our application.
 */
// Desired output structure:
// {
//   id: string,
//   userId: string, // if different from id
//   name: string,
//   email: string,
//   registeredAt: Date,
//   status: 'active' | 'inactive',
//   location: { street: string, city: string, postalCode: string }
// }

/**
 * Function to transform the user API response into the standardized model.
 * @param {object} apiResponse - The raw response from the user API.
 * @returns {object|null} The normalized user object or null if data is invalid.
 */
function normalizeUser(apiResponse) {
  const userData = apiResponse?.data;
  if (!userData) return null;

  return {
    id: userData.id,
    userId: userData.id, // Assuming id and userId are the same for this source
    name: userData.username, // Mapping 'username' to 'name'
    email: userData.emailAddress,
    registeredAt: new Date(userData.creationDate),
    status: userData.isActiveUser ? 'active' : 'inactive',
    location: {
      street: userData.addressInfo?.street || '',
      city: userData.addressInfo?.city || '',
      postalCode: userData.addressInfo?.zip || '' // Renaming 'zip' to 'postalCode'
    }
  };
}

/**
 * Function to transform the profile API response into the standardized model.
 * Note: This might represent a partial user profile that needs to be merged.
 * @param {object} apiResponse - The raw response from the profile API.
 * @returns {object|null} The normalized profile object or null if data is invalid.
 */
function normalizeProfile(apiResponse) {
  const profileData = apiResponse?.result;
  if (!profileData) return null;

  return {
    id: profileData.profileId, // Using profileId as the primary ID for this source
    userId: profileData.userIdRef,
    name: profileData.displayName, // Mapping 'displayName' to 'name'
    email: profileData.contactEmail,
    registeredAt: new Date(profileData.registrationTimestamp),
    status: profileData.status === 'active' ? 'active' : 'inactive'
  };
}

// --- Usage Example ---
const normalizedUser = normalizeUser(userApiResponse);
console.log('Normalized User from User API:');
console.log(JSON.stringify(normalizedUser, null, 2));

const normalizedProfile = normalizeProfile(profileApiResponse);
console.log('
Normalized Profile from Profile API:');
console.log(JSON.stringify(normalizedProfile, null, 2));

// If we need to merge them (common scenario):
const combinedUser = {
  ...normalizedUser, // Start with user data
  ...(normalizedProfile && { // Overlay with profile data, ensuring profileData exists
    id: normalizedUser.id, // Preserve primary ID from user API, or decide on a merging strategy
    name: normalizedProfile.name, // Profile name might be preferred
    email: normalizedProfile.email, // Profile email might be more current
    // ... other fields from profile that should override or complement
  })
};

console.log('
Combined (Normalized) User Data:');
console.log(JSON.stringify(combinedUser, null, 2));