How can I turn this nested if function into functional style programming with Ramda in Javascript

Question

I was looking at the code in Prisma for softdelete middleware:

  prisma.$use(async (params, next) => {
    // Check incoming query type
    if (params.model == 'Post') {
      if (params.action == 'delete') {
        // Delete queries
        // Change action to an update
        params.action = 'update'
        params.args['data'] = { deleted: true }
      }
      if (params.action == 'deleteMany') {
        // Delete many queries
        params.action = 'updateMany'
        if (params.args.data != undefined) {
          params.args.data['deleted'] = true
        } else {
          params.args['data'] = { deleted: true }
        }
      }
    }
    return next(params)
  })

The steps it takes is: Check if Post -> if it's a 'delete' or 'deleteMany' then change action to 'update' and set deleted to true.

The nested if's seems not ideal and it seemed that this would be cleaner using a functional style, so I used Ramda to try and make it functional:

const model = lensProp('model')
const action = lensProp('action')
const argsData = compose(lensProp('args'), lensProp('data'))
const cView = curry(view)
const modelView = cView(model)
const actionView = cView(action)
const _shouldBeModified = (models, actions, p) => and(
    includes(modelView(p), models),
    includes(actionView(p), actions)  
)
const shouldBeModified = curry(_shouldBeModified)
const timeElapsed = Date.now();
const today = new Date(timeElapsed);

const softDelete = (models, actions, params) => ifElse(
  shouldBeModified(models, actions), 
  pipe(
    set(argsData, { deleted: true, deletedAt: today.toISOString()}), 
    set(action, 'update')
  ),
  identity
)(params)

I can then call it like this:

softDelete(['Post'],['delete', 'deleteMany'],params)

/*
 returns: {"action": "update", "args": {"data": {"deleted": true, "deletedAt": "2022-04-17T19:49:00.294Z"}}, "model": "Post"}
*/

All of that said, I'm new to Ramda and it seems like my approach is messy, can someone help me clean this up?

Answer 1

You can use R.when with R.where to check if the params should be updated. If so, use R.evolve to update them.

Pass an actions object, instead of an array, so the code can map the update / updateMany according to the original action.

const { curry, when, where, includes, __, keys, evolve, prop, mergeDeepLeft } = R

const actionsMap = { delete: 'update', deleteMany: 'updateMany' };

const softDelete = curry((models, actions, params) => when(
  where({
    model: includes(__, models),
    action: includes(__, keys(actions))
  }),
  evolve({
    action: prop(__, actions),
    args: mergeDeepLeft({ data: { deleted: true, deletedAt: new Date().toISOString() }})
  })
)(params))

const params = {"action": "deleteMany", "args": { data: { something: 5 } }, "model": "Post"}

const result = softDelete(['Post'], actionsMap, params)

console.log(result)

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