Add support for $and

[vonagam]

My use case for this method is a permissions hook. I want to add restrictions to which record user might find. It may be convenient to do by replacing params.query with {$and: [originalQuery, restrictionsQuery]} in a before hook. Without $and it is not trivial to combine two arbitrary queries.

[daffl]

Thank you for the pull request! How do the queries look like? Not opposed to adding this operator but normally combining them (e.g. with Object.assign({}, orginalQuery, restrictionsQUery) should accomplish the same thing.

[vonagam]

First, example:
originalQuery is {category: "bar"}.
restrictionsQuery is {category: "foo"}.
We expect that there will be no results as there is no intersection.
But if we assign them then we will show foo category.

Second, i checked and it seems that this syntax:
.find([originalQuery, restrictionsQuery]) already works (maybe unintentionally because Object.keys works on arrays too).
So for my use case current functionality is enough.
(Still if it is unintentional as there is no docs or tests, i would risk to lose this way in future releases)

[vonagam]

And this is just simplest example. More complex example is if both original and restrictions query contain $or field.

[daffl]

Makes sense, otherwise you'd have to do a some merging around in that case. If you could add documentation for this in https://github.com/feathersjs-ecosystem/feathers-knex#querying we can get it released.

[vonagam]

Added simplest description. Don't know if specified REST API url right (array with nested objects...).

[daffl]

Perfect. Released as v3.3.0, thank you!

[vonagam]

Thanks for super fast response.