Ordering and Limiting

Table of contents

1. Ordering and Limiting
   1. Order and limit data
   2. Limit data at end
   3. Sub collection
      1. Sample Data
      2. Example Usage

FireO provides powerful query functionality for specifying which documents you want to retrieve from a collection. These queries can also be used with either get() or fetch()

Order and limit data

By default, a query retrieves all documents that satisfy the query in ascending order by document ID. You can specify the sort order for your data using orderBy(), and you can limit the number of documents retrieved using limit() or passing number of documents in fetch(limit).

For example, you could query for the first 3 cities alphabetically with:

await City.collection.orderBy("name").limit(3).fetch();

// Same thing can be achieved by passing limit in fetch() method
await City.collection.orderBy("name").fetch(3);

You could also sort in descending order to get the last 3 cities:

await City.collection.orderBy("-name").fetch(3);

You can also order by multiple fields. For example, if you wanted to order by state, and within each state order by population in descending order:

await City.collection.orderBy("state").orderBy("-population");

You can combine where() with order() and limit(). In the following example, the queries define a population threshold, sort by population in ascending order, and return only the first few results that exceed the threshold:

await City.collection
  .where("population", ">", 2500000)
  .orderBy("population")
  .limit(2)
  .fetch();

However, if you have a filter with a range comparison (<, <=, >, >=), your first ordering must be on the same field:

Valid: Range filter and orderBy on the same field

await City.collection
  .where("population", ">", 2500000)
  .orderBy("population")
  .fetch();

Invalid: Range filter and first orderBy on different fields

await City.collection.where("population", ">", 2500000).orderBy("country");

Limit data at end

Limit documents at the end of collection, For example you want to get the last 3 documents in ascending order.

Note: You must specify at least one orderBy clause for limitToLast queries, otherwise an exception will be thrown during execution.

const { Model, Field } = require("fireo");

class LimitModel extends Model {
  number = Field.Number();
  collection_number = Field.Number();
  content = Field.Text();
}

const docs = await LimitModel.collection
  .where("collection_number", "==", 1)
  .orderBy("number")
  .limitToLast(3)
  .fetch();

Sub collection

Sub collection queries work in same fashion but you need to pass parent_key to search in specific collection. Ordering and limiting apply same like other root collection

Sample Data

const { Model, Field } = require("fireo");

class Post extends Model {
  title = Field.Text();
  content = Field.Text();
}

class Review extends Model {
  name = Field.Text();
  stars = Field.Number();
}

const p = Post.fromObject({ title: "First Post", content: "Some Content" });
await p.save();

const r1 = Review.init({ parent: p.key });
r1.name = "Azeem";
r1.stars = 5;
await r1.save();

const r2 = Review.init({ parent: p.key });
r2.name = "Arfan";
r2.stars = 3;
await r2.save();

Example Usage

The following query returns all reviews order by review stars

const reviews = await Review.collection
  .parent(post_key)
  .orderBy("stars")
  .fetch();