Prisma does not have any JSON filter (See this issue). This repo is to showcase a way to filter the JSON data using mingo.

---

How it works?

We create a minimal graphql server with graphql-yoga, however it could be express or anything else. It has one query which returns json data.

Generate Fake Data

fakeData generates 5 to 20 fake objects so we don't need a database to test out how it works.

Schema

It has a simple query people which takes a schemaless raw JSON data. The data can be anything but since we are trying to filter, we assume it's an array (of objects).

Sample Query

Fetch all results

{
  people
}

Filter Data

filterData is simply a function that takes the fake data and applies mongodb like cursor.

skip and first

It has skip and first just like we need in a prisma/graphql filter.

Fetch result with some filter

{
  people(first: 2, skip: 1)
}

This query skips the first element and then returns 2 results. In prisma, first is like an alias for limit.

Here is the result:

query

Warning! Beyond this point, it gets really complex. Caution adviced. You probably don't need these.

Example

The query filter takes a stringified json. Consider the following query you would do on mongodb,

{
  id: {
    $gte: 50000;
  }
}

You need to turn this into an string and pass that,

JSON.stringify(JSON.stringify({ id: { $gte: 50000 } }));
// "{\"id\":{\"$gte\":50000}}"

So now the query becomes:

{
  people(query: "{\"id\":{\"$gte\":50000}}")
}

You can probably implement all other type of filter based on the above logic.

Another Example

For example, filter all element which has name with letter a, with Regex:

JSON.stringify(JSON.stringify({ name: { $regex: "a" } }))
// "{\"name\":{\"$regex\":\"a\"}}"

The query becomes:

{
  people(query: "{\"name\":{\"$regex\":\"a\"}}")
}

Result:

To understand what kind of filter you can probably use, check the mingo repository.