useCodingTask hook

The useCodingTask hook is a custom React hook that provides functionality for fetching and managing coding task data in the advanced to-do application. It enriches the basic task data with user information and metadata to create a comprehensive data structure that components can easily consume.

The useCodingTask hook leverages the Ontology SDK (OSDK) to interact with backend services in a type-safe manner, using the powerful $as operator to pivot between different object type implementations. It also demonstrates effective use of React's state management and memoization patterns to optimize performance.

View the useCodingTask reference code.

Key functions

Uses React's useCallback for memoizing functions to prevent unnecessary re-renders
Leverages SWR's (stale-while-revalidate) caching to reduce redundant API calls
Implements component-specific data fetching tied to the parent task ID
Provides access to both data and metadata for rich UI experiences
Ensures type-safety through the use of TypeScript and the OSDK
Employs the $as operator for type-safe pivoting between object types
Disables automatic revalidation to optimize network usage

`useCodingTask` structure

Interface definition

Copied!1
2
3
4
5
interface CodingTaskEnriched {
  osdkCodingTask: osdkCodingTask.OsdkInstance;
  createdBy: User;
  assignedTo: User;
}

This interface combines the SDK's coding task instance with user objects for the task creator and assignee, creating a unified data structure that simplifies component implementation.

Data fetching

The useCodingTask hook uses SWR data fetching capabilities with a custom fetcher function that does the following:

Uses the $as operator to pivot to the coding task interface implementation
Utilizes user data already included in the parent task
Constructs the CodingTaskEnriched object with the retrieved data
Returns the enriched data structure for SWR to cache

Copied!1
2
3
4
5
6
7
8
9
const fetcher = useCallback(async () => {
    const codingTask = task.osdkTask.$as(osdkCodingTask);
    const codingTaskEnriched = {
        osdkCodingTask: codingTask,
        createdBy: task.createdBy,
        assignedTo: task.assignedTo,
    };
    return codingTaskEnriched;
}, [task]);

The useCodingTask hook configures SWR to minimize unnecessary network requests:

Copied!1
2
3
4
{ 
    revalidateOnFocus: false,
    revalidateOnReconnect: false,
}

Metadata access

The useCodingTask hook retrieves object type metadata to enable dynamic UI features:

Copied!1
2
3
4
5
6
7
8
const getObjectTypeMetadata = useCallback(async () => {
    const objectTypeMetadata = await client.fetchMetadata(osdkCodingTask);
    setMetadata(objectTypeMetadata);
}, [client]);

useEffect(() => {
    getObjectTypeMetadata();
}, [getObjectTypeMetadata]);

This metadata provides information about the coding task object type (such as display names and field configurations) that components can use for rendering.

Return value

The useCodingTask hook returns an object with the following structure:

Copied!1
2
3
4
5
6
7
{
  codingTask: CodingTaskEnriched | undefined;  // The enriched coding task (undefined if not loaded)
  isLoading: boolean;                          // True during initial data loading
  isValidating: boolean;                       // True during background revalidation
  isError: any;                                // Error object if the request failed
  metadata: ObjectMetadata | undefined;        // Metadata about the coding task object type
}

This comprehensive return value gives components all the information they need to handle various states and render the appropriate UI.

Implementation

Object type pivoting with $as

The useCodingTask hook uses the $as operator to pivot between related object types:

Copied!1
const codingTask: osdkCodingTask.OsdkInstance = task.osdkTask.$as(osdkCodingTask);

This pattern leverages TypeScript's type system to safely transition between related object types:

The base task object (task.osdkTask) has a polymorphic structure
The $as operator performs a runtime check to verify compatibility
The result is a fully typed instance with access to coding-task-specific properties

This approach is essential for polymorphic data models where a base object can have specialized subtypes.

Memoization with useCallback

The hook employs React's useCallback to optimize performance:

Copied!1
2
3
4
5
6
7
const fetcher = useCallback(async () => {
    // Fetcher logic
}, [task]);

const getObjectTypeMetadata = useCallback(async () => {
    // Metadata fetching logic
}, [client]);

This pattern dose the following:

Prevents unnecessary recreations of function references on each render
Only rebuilds functions when dependencies change
Reduces unnecessary effect triggers and API calls
Optimizes the hook for use in memoized components

External packages

The following external packages can be used with the useCodingTask hook.

@osdk/client and @osdk.react

Purpose: Ontology SDK client for interacting with a backend data service Benefits:

Provides type-safe interfaces for data models
Enables structured data queries and metadata access
Exposes hooks like useOsdkClient for accessing the client instance
Supports metadata retrieval for dynamic UI rendering

@advanced-to-do-application/sdk

Purpose: Application-specific SDK with predefined data types. Benefits:

Contains the data model specific to coding tasks (osdkCodingTask).
Provides typed access to coding task properties.
Enables type-safe pivoting between related object types
Supports the object inheritance model used in the application

useSWR

Purpose: Data fetching, caching, and state management Benefits:

Provides an elegant way to fetch and cache coding task data
Handles loading and error states automatically
Offers built-in revalidation strategies
Simplifies data access with conditional fetching.
Reduces redundant API calls with intelligent caching

Usage example

Copied!1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
function CodingTaskDetails({ task }) {
  const { codingTask, isLoading, isError, metadata } = useCodingTask(task);
  
  if (isLoading) return <div>Loading coding task details...</div>;
  if (isError) return <div>Error loading coding task: {isError.message}</div>;
  if (!codingTask) return <div>No coding task found</div>;
  
  return (
    <div className="coding-task-details">
      <h2>{codingTask.osdkCodingTask.title}</h2>
      
      <div className="metadata-section">
        <h3>Task Metadata</h3>
        <div>Object Type: {metadata?.displayName || "Coding Task"}</div>
      </div>
      
      <div className="code-section">
        <h3>Code Requirements</h3>
        <div className="language-badge">{codingTask.osdkCodingTask.language}</div>
        <pre>
          <code>{codingTask.osdkCodingTask.codeSnippet}</code>
        </pre>
      </div>
      
      <div className="people-section">
        <h3>People</h3>
        <div className="assigned-to">
          <span>Assigned to: </span>
          <span>{codingTask.assignedTo?.displayName || "Unassigned"}</span>
        </div>
        <div className="created-by">
          <span>Created by: </span>
          <span>{codingTask.createdBy?.displayName || "Unknown"}</span>
        </div>
      </div>
    </div>
  );
}

Edge cases and limitations

Consider the following scenarios and limitations before using the useCodingTask hook:

Missing user data: If the parent task does not include user data, the hook will still function but will return undefined for createdBy or assignedTo. Components should handle this gracefully.
Invalid type pivoting: If the task object cannot be pivoted to a coding task (for example, if it is actually a different task type), the $as operation may fail at runtime. The hook does not currently handle this error case explicitly.
Metadata loading: Metadata is loaded separately from the task data. This means there might be a brief period where the task data is available but the metadata is still loading. Components should account for this possibility.
Dependency on parent task: The useCodingTask hook depends entirely on the parent task object. If that object is malformed or missing essential data, the hook may not function as expected.
No mutation support: While the hook provides data fetching capabilities, it does not include functions for updating, creating, or deleting coding tasks. A separate hook or extension would be needed for these operations.
Performance with large data: For tasks with very large code snippets or extensive metadata, performance might be impacted. Consider implementing virtualization or pagination for such cases.
Network error handling: The hook exposes errors but does not retry failed requests automatically. Applications may need to implement their own retry logic for unstable networks.