[Feature request] Pass default handler to customHandlers

[cibernox]

I'll expose my use case to see if you see this as something it might worth to add.

I have some index routes where I need to perform pagination (and also filtering if a filter=abc query param is received) but also they need to handle coalescedRequests like /posts?ids=1,3,5.

I've defined a custom hander like this one:

this.get('/posts', function(store, request) {
  if (request.queryParams.ids) {
    // mimic default behavior
  } else {
    let results = store.findAll('post');
    let payload = {};
    if (request.queryParams.filter) {
      // do filter
    }
    // bla bla construct meta 
    return payload
  }
});

I thought that a situation where you want to use the default behavior or a slightly modified version of the default behavior, receiving the default handler as a third parameter in that function could be useful.

P.e:

this.get('/posts', function(store, request, defaultHandler) {
  if (request.queryParams.ids) {
    return defaultHandler(store, request);
  } else {
    return myCustomPayload;
  }
});

or

this.get('/posts', function(store, request, defaultHandler) {
  var payload = defaultHandler(store, request);
  payload.meta = { page: 1, timestamp: (new Date()).toString() };
  return payload;
});

Thoughts? I've located the part of the code that has to be changed and seems fairly minimal.

[samselikoff]

defaultHandler being what gets called when there's no second param passed to this[verb]?

In your second case defaultHandler would then just return db.contacts, so you could write

this.get('/posts', function(db, request, defaultHandler) {
  var payload = db.contacts;
  payload.meta = { page: 1, timestamp: (new Date()).toString() };
  return payload;
});

(btw it's db instead of store now)

[samselikoff]

just to clarify, because the default handler changes based on the second param to this[verb] (undefined, array, string etc.)

[cibernox]

Yes, with defaultHandler being the default handler of the route if no second argument is passed (although a this.get('/posts', 'article', function(db, request, handler) being handler the customized handler given the 2nd argument can also be useful)

In my second example it's not that simple as db.contacts, because the default handler takes care of coalesced requests like /posts?ids=1,3,5, while db.contacts returns all.

[samselikoff]

still confused...

because the default handler takes care of coalesced requests like /posts?ids=1,3,5, while db.contacts returns all.

bey default handler here are you referring to the first one that you wrote within your own mirage/config.js file?

[samselikoff]

might be easy if you just gist me the entire /mirage/config.js file, I haven't had a chance to use mirage with an app with lots of filtering/sorting so I'm not familiar with some of these pain points

[cibernox]

I have a few routes that follow the same patterns, so I created a function that generates functions.

import config from '../config/environment';
var defaultPageSize = config.APP.defaultPageSize;

function servePaginatedAndCoalesced(type, { filterField }) {
  let normalizedType = type.underscore();
  let normalizedCollectionType = type.pluralize().underscore();

  return function(store, request) {
    let results = store.findAll(normalizedType);
    let ids = request.queryParams.ids;
    if (ids) {
      return { [normalizedCollectionType]: results.filter(e => ids.indexOf(''+e.id) > -1) };
    } else {
      let total   = results.length;
      let page    = 1;
      let filter  = request.queryParams.filter;
      if (filter && filter.length > 1) {
        filter  = filter.toLowerCase();
        results = results.filter(s => s[filterField].toLowerCase().indexOf(filter) > -1);
      }
      let payload = {};
      let pagedResults = results.slice(0, defaultPageSize);
      payload.meta = { total, page };
      payload[normalizedCollectionType] = pagedResults;
      return payload;
    }
  };
}

  this.get('/schools', servePaginatedAndCoalesced('school', { filterField: 'name' }));
  this.get('/teachers', servePaginatedAndCoalesced('teacher', { filterField: 'surname' }));
  this.get('/staff_members', servePaginatedAndCoalesced('staff_member', { filterField: 'surname' }));
  this.get('/students', servePaginatedAndCoalesced('student', { filterField: 'surname' }));
  // And some more

The real backend will a full featured elastic search filtering, but in mirage I am just creating some endpoints that:

1. When requested without queryParams, return the first 10 elements in the collection and a meta on the root.
2. When requested with ids=1,3,5, returns only the elements with those IDs (for enable coalescing)
3. When receives a ?filter=abc qp and that filter string is long enough (>1 chars) I filter the results by some field.

The reason why I wanted to receive the defaultHandler is to avoid to implement the point 2 myself.

[samselikoff]

So I think one solution to this would be to define routes that differentiate on query params, for example:

this.get('/schools?ids=:ids', function(store, request) {
  let ids = request.queryParmas.ids;
  // query logic
});
this.get('/schools');  // default

Others have requested this too, e.g. to split up query logic across routes. Would this suit your purposes here? Or are you requesting a generic handler build-in to Mirage that understands ?ids=1,3,5?

[cibernox]

That is good enough for most use cases 👍

[samselikoff]

Filing this under the "Calling super / expose default route handler" note in the roadmap