Creating Indexes

What is the shape of your data? For any properties you want to filter/refine, you need to define an Index.

Imagine we had data that looked like this:

let items = [
  { title: "Watch the new Matrix", id: 1, tags: ["fun"] },
  { title: "Cut the grass", id: 2, ["chore", "lawn"] },
  { title: "Buy fetilizer", id: 4, tags: ["lawn", "shopping"] },
  { title: "Build RefinerDB", id: 3, ["fun", "code"] },
  { title: "Document RefinerDB", id: 11, ["chore", "code"] },
];

We would create a RefinerDB instance then define two indexes, one for title, and one for tags. We won't need to filter or sort by id, so we dont' need an Index for it.

import { RefinerDB, IndexType } from "refinerdb";

let refinerDB = new RefinerDB("my-db");
let indexDefinitions = [
  { key: "tags", type: IndexType.String },
  // Because all of the titles are generally unique, generating a list of
  // refiner options and their counts is not that useful. We can improve
  // performance by skipping that step.
  { key: "title", type: IndexType.String, skipRefinerOptions: true },
];
refinerDB.setIndexes(indexDefinitions);

Here are the available IndexType options, and the full type definition for IndexConfig.

enum IndexType {
  String = "string",
  Number = "number",
  Date = "Date",
}

Indexed values

refinerDB will loop through all your items and get an indexed value for each registered index.

There are a few ways to tell refinerDB what to index

key

The index key can be used if the item's property name matches the index key.

Given the following item to index

{ title: "Item One", id: 1 }

The following index would yield an indexed value of "Item One"

{ key: "title", type: IndexType.String }

path

If the item doesn't have a property whose name matches the index key, you can specify an index path.

• The path can point to a nested property, like "author.firstName"

Given the following item to index

{
  id: 1,
  title: "Item One",
  author: {
    firstName: "Jane",
    lastName: "Doe"
  }
}

The following index would yield an indexed value of "Jane"

{
  key: "author",
  type: IndexType.String,
  path: "author.firstName"
}

map(item => indexedValue)

The most flexible way to index an item value is to use a custom map function.

{
  id: 1,
  title: "Item One",
  author: {
    firstName: "Jane",
    lastName: "Doe"
  }
}

The following index would yield an indexed value of "Jane Doe"

{
  key: "author",
  type: IndexType.String,
  map: (item => `${item.firstName} ${item.lastName}`)
}