Practical Microservices

Ensuring Uniqueness of Email Addresses

Next up is loadExistingIdentity, and this function is defined at:

video-tutorials/src/app/register-users/load-existing-identity.js

function loadExistingIdentity (context) {
  return context.queries
    .byEmail(context.attributes.email)
    .then(existingIdentity => {
      context.existingIdentity = existingIdentity

      return context
    })
}

module.exports = loadExistingIdentity

Following Eric Elliot’s advice in his article “Mocking Is a Code Smell,”^[48] this function does the single job of querying View Data for a record with the given email address. It doesn’t check to see if it actually found one because that would be mixing I/O (the query) and branching business logic. This function’s job is to ...