Collection utilities

Overview

The utils.collection.js module provides utility functions for interacting with collections in a KDK-based application. It leverages Lodash for object manipulation and FeathersJS services to perform database operations efficiently.

Functions

1. getCollectionService(name, context)

Description: Retrieves a service instance for a specified collection.

• Parameters:
  • name (string): The name of the collection service.
  • context (object): The context in which the service operates.
• Returns: The requested service instance.

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2. listItems(service, fields, filter = {}, limit = 50)

Description: Fetches a list of items from a given service, applying optional filters and field selection.

• Parameters:
  • service (object): The service instance to query.
  • fields (array): The fields to select in the query.
  • filter (object, optional): Additional query filters.
  • limit (number, optional, default=50): The maximum number of items to retrieve.
• Returns: A promise resolving to the list of retrieved items.

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3. getOldestItem(service, field = 'createdAt', filter = {})

Description: Retrieves the oldest item from a service based on a specified field.

• Parameters:
  • service (object): The service instance to query.
  • field (string, optional, default='createdAt'): The field used to determine the oldest item.
  • filter (object, optional): Additional query filters.
• Returns: A promise resolving to the oldest item.

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4. getOldestTime(service, field = 'createdAt', filter = {})

Description: Retrieves the timestamp of the oldest item from a service based on a specified field.

• Parameters:
  • service (object): The service instance to query.
  • field (string, optional, default='createdAt'): The field used to determine the oldest timestamp.
  • filter (object, optional): Additional query filters.
• Returns: A promise resolving to the timestamp of the oldest item.

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5. getLatestItem(service, field = 'createdAt', filter = {})

Description: Retrieves the latest item from a service based on a specified field.

• Parameters:
  • service (object): The service instance to query.
  • field (string, optional, default='createdAt'): The field used to determine the latest item.
  • filter (object, optional): Additional query filters.
• Returns: A promise resolving to the latest item.

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6. getLatestTime(service, field = 'createdAt', filter = {})

Description: Retrieves the timestamp of the latest item from a service based on a specified field.

• Parameters:
  • service (object): The service instance to query.
  • field (string, optional, default='createdAt'): The field used to determine the latest timestamp.
  • filter (object, optional): Additional query filters.
• Returns: A promise resolving to the timestamp of the latest item.

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7. enumerateField(service, field, filter = {})

Description: Retrieves a list of distinct values for a specified field in a collection.

• Parameters:
  • service (object): The service instance to query.
  • field (string): The field for which distinct values are required.
  • filter (object, optional): Additional query filters.
• Returns: A promise resolving to an array of unique values.

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Usage Example

import { getCollectionService, listItems } from './utils.collection.js';

const service = getCollectionService('myCollection', context);
const items = await listItems(service, ['name', 'age'], { active: true }, 100)
console.log('Active items:', items);