Querying the Custom Entity Store

You can build complex queries against data stored in the Custom Entity Store using a wide variety of filters and conditions.

To start, import the Forge KVS package in your app, as follows:

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import { kvs } from '@forge/kvs';

Each installation of your app is subject to the API's quotas and limits. See Storage quotas and Storage limits for more details.

Scope requirement

Using the @forge/kvs package requires the storage:app scope in your manifest file:

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permissions:
  scopes:
    - storage:app

See Permissions for more information about scopes.

Related information

Before you can store data in the Custom Entity Store, you'll need to declare your custom entities and indexes first in your app's manifest file. Custom entities are user-defined data structures for storing app data. Forge's storage API lets you query data stored in these structures using a wide array of query conditions. These query conditions make it possible to build advanced, complex queries to suit your app's operations.

For information about storing data to the Custom Entity Store, see Storing data in custom entities .

For a detailed tutorial on storing and querying structured data through custom entities, see Use custom entities to store structured data.

Basic methods

All complex queries operate on a custom entity's index. Complex queries follow the same basic signature:

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await kvs
  .entity("<custom-entity>")
  .query()
  .index()

This structure contains all the required methods for a complex query. The entity method sets which custom entity to query, and index sets which of those entity's indexes to query. Each query can only target one index from one custom entity.

When using indexes that feature a partition, you must specify a value to match the parameter's attribute:

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await kvs
  .entity("<custom-entity>")
  .query()
  .index("<index-name>", {
    partition: ["<value>"]
  })

If your index's partition has multiple attributes, then you must set a value for each attribute. In addition, you must also set each value in the order they are declared in the index. For example, consider the following index:

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indexes:
  - name: by-gender-and-age
    range: 
      - employmentyear
    partition: 
      - gender
      - age

An appropriate query for this would be:

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await kvs
  .entity("employee")
  .query()
  .index("by-gender-and-age", {
    partition: ["male", 20]
  })
  .where(WhereConditions.greaterThan(2003))

This query will fetch employees who are:

• male
• 20 years old
• employed after 2003 (that is, employmentyear is higher than 2003).

where

While index lets you filter matches to an index's partition, where lets you filter against an index's range. To use the where filter:

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import { WhereConditions } from '@forge/kvs';

Method signature

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.where(WhereConditions.<condition>("<value>"))

Conditions

The where filtering method supports the following conditions:

• beginsWith
• between
• equalTo
• greaterThan, lessThan
• greaterThanEqualTo, lessThanEqualTo

beginsWith condition

Constructs a predicate used in the query.where method to filter results. beginsWith enforces that the specified field must start with the specified string.

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beginsWith(value: string): Predicate

filters

The filters method allows you to filter the query results with multiple conditions. You can use the filters method once in a query, but it can include multiple conditions by utilizing various filtering methods and conditions.

Method signature

To use filtering methods and and or,

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import { Filter, FilterConditions } from '@forge/kvs';

and create a new Filter instance:

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new Filter()

Each filtering method use the following signatures:

• and: all conditions must be matched.

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  new Filter().and("<attribute>", FilterConditions.<condition>("<value>"))
  

• or: only one condition must be matched.

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  new Filter().or("<attribute>", FilterConditions.<condition>("<value>"))
  

Conditions

Both filtering methods support the following conditions:

• beginsWith
• between
• equalTo, notEqualTo
• greaterThan, lessThan
• greaterThanEqualTo, lessThanEqualTo
• exists, notExists
• contains, notContains

sort

The sort method displays your results in either ascending (ASC) or descending (DESC) order:

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.sort(Sort.<"ASC|DESC">)

By default, results are displayed in ascending order.

query.limit

Returns a new Query with a limit on how many matching values get returned. The query API returns up to 10 values by default, this can be increased to a maximum of 100.

Method signature

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query().limit(limit: number): Query

query.cursor

Returns a new Query that will start after the provided cursor. Cursors enable your app to fetch subsequent pages of results after completing an initial query.

Cursors are returned from the getMany query API.

Method signature

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query().cursor(after: string): Query;

query.getMany

Execute the query and return a list of results up to the provided limit in length. This method returns both the array of results and a cursor that's used to fetch subsequent pages of results.

Method signature

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query().getMany(): Promise<ListResult<T>>;

interface ListResult<T> {
  results: Result<T>[];
  nextCursor?: string;
}

export interface Result<T> {
  key: string;
  value: T;
}

query.getOne

Execute the query and get the first matching result, if any matches exist. If there is no match, the result resolves to undefined.

Method signature

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query().getOne(): Promise<Result<T> | undefined>;

export interface Result<T> {
  key: string;
  value: T;
}

Example entity

The following manifest.yml excerpt shows a custom entity named employee with several attributes and indexes:

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app:
  id: "ari:cloud:ecosystem::app/406d303d-0393-4ec4-ad7c-1435be94583a"

  storage:
    entities:
      - name: employee
        attributes:
          surname: 
            type: string
          age: 
            type: integer
          employmentyear: 
            type: integer
          gender: 
            type: string
          nationality: 
            type: string
        indexes:
          - surname
          - employmentyear
          - name: by-age
            range: 
              - age
          - name: by-age-per-gender
            partition: 
              - gender
            range: 
              - age  

This entity also creates four indexes based on the following employee attributes:

• surname
• employmentyear
• age (further optimized for filtering according to different age ranges)
• age per gender (further optimized for filtering according to age ranges for each gender)

Example queries

Using the previous section's example entity and its indexes, the following queries demonstrate the use of each method:

Simple index

Targets the surname index of the employee entity.

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await kvs
  .entity("employee")
  .query()
  .index("surname")
  .getMany()

Simple index with where condition

Targets the by-age index, which uses age as its range. From this, the where method will limit matches to employees above the age of 30. Results will be displayed in descending order.

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await kvs
  .entity("employee")
  .query().index("by-age")
  .where(WhereConditions.isGreaterThan(30))
  .sort(SortOrder.DESC)
  .getMany()

Named index with partition

Targets the by-age-per-gender index, and will limit matches to female employees.

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await kvs
  .entity("employee")
  .query()
  .index("by-age-per-gender", {
    partition: ["female"]
  })
  .getMany()

Named index with partition and filters

Using the by-age-per-gender index, limits matches only to female Australian employees above the age of 30 who were also hired after 2020.

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await kvs
  .entity("employee")
  .query()
  .index("by-age-per-gender", {
    partition: ["female"]
  })
  .where(WhereConditions.isGreaterThan(30))
  .filters(new Filter()
    .and("employmentyear", FilterConditions.isGreaterThan(2020))
    .and("nationality", FilterConditions.equalsTo("Australian"))
  )
  .getMany()