feature: add Catalog query filters

[willopez]

Impact: minor
Type: feature

Feature

Adds Boolean filtering support for the catalogItems query. Filters are specified as a key value pair of a supported filter field,(see below) and a boolean value. A booleanFilters param will need to be sent with requests to the catalogItems query. These filters are optional.

Example query

query catalogItemsQuery($shopId: ID!, $tagIds: [ID], $booleanFilters: [CatalogBooleanFilter], $first: ConnectionLimitInt, $last:  ConnectionLimitInt, $before: ConnectionCursor, $after: ConnectionCursor, $sortBy: CatalogItemSortByField, $sortByPriceCurrencyCode: String, $sortOrder: SortOrder) {
  catalogItems(shopIds: [$shopId], tagIds: $tagIds, booleanFilters: $booleanFilters, first: $first, last: $last, before: $before, after: $after, sortBy: $sortBy, sortByPriceCurrencyCode: $sortByPriceCurrencyCode, sortOrder: $sortOrder) {
.
.
.
  }
}

Example filters:

[
        {
          name: "isSoldOut",
          value: false
        },
        {
          name: "isBackorder",
          value: false
        }
]

Currently supported fields

isDeleted | Boolean
isVisible | Boolean
isLowQuantity | Boolean
isSoldOut | Boolean
isBackorder | Boolean

Testing

1. In the storefront, add filters as specified above
2. confirm products are correctly filtered

[willopez]

@mikemurray FYI, there are some tests failing that were already failing. I fixed the one related to this PR.

[willopez]

@mikemurray this is now ready for review, the underlying inventory issue has been resolved.

[mikemurray]

@willopez Allowing strings of JSON for filters is not the way to go because you're exposing mongo functionality in an API that needs to be agnostic of its underlying database. This also opens the door to random code injection and has security/performance concerns.

These filters need to be defined in the GraphQL schema so they are limited to only what's necessary, reducing the possibility of code injection, and the benefit of being introspectable.

[willopez]

@mikemurray I have refactored the filters to be of Boolean type and restricted the props on which to filter on with an enum.

[aldeed]

I left a few inline comments.

Big picture, I think this is generally fine but we can't do it quite like this. Three of the filters, isLowQuantity, isSoldOut, and isBackorder are fields added and controlled by the inventory plugin, so catalog code should not reference them. So you'll need to add a way for any plugin to add supported filters, and then move these to the inventory plugin.

I think functionsByType is a good choice here. It could be called xformCatalogFilters, same as you have. Rather than calling just the one from this plugin, you'd loop over all functions registered as that type in series, and for each one that returns a Mongo filter object, merge them all together to build the final catalogFilters object. So each plugin can handle whatever filters it handles.

You'll also need to move those GraphQL schema enum values into the inventory plugin using extend enum there.

[willopez]

@aldeed I have resolved all your previous comments. Wondering if I should created indices for

isDeleted
isVisible
isLowQuantity
isSoldOut
isBackorder

[aldeed]

I'm approving the code but I did not test. @willopez Indexes are generally not very useful for fields with boolean values. The more possible values a field has, the more an index helps. But by their nature boolean fields only have 2 possible values. (ref: https://docs.mongodb.com/manual/tutorial/create-queries-that-ensure-selectivity/) So I think we can hold off adding indexes for these unless we find out they are indeed helpful in the wild.