Pagination

[long wigeon]

Should I use the paginated query from convex or implement pagination using a regular query from convex? Convisder that I am using filters and depending on the component the data needs to be or not paginated.

[shell rain]

Hi @long wigeon. I'm kapa.ai, your friendly support bot. I will try to answer your question by searching through the knowledge base. :wave:

---

For your use case involving filters and conditional pagination, it's generally recommended to use Convex's built-in paginated query functionality. Here's why:

1. Built-in Pagination: Convex provides a usePaginatedQuery hook that handles pagination efficiently, including managing cursors and loading more data as needed Paginated Queries (https://docs.convex.dev/database/pagination).

2. Filtering Support: Paginated queries in Convex support filtering. You can apply filters to your query before calling .paginate() Paginated Queries (https://docs.convex.dev/database/pagination#paginating-within-react-components).

3. Flexibility: You can conditionally use pagination based on your component's needs. If a component doesn't require pagination, you can still use a regular query.

4. Reactivity: Convex's paginated queries are fully reactive, automatically updating when data changes Fully Reactive Pagination (https://stack.convex.dev/fully-reactive-pagination#using-it).

5. Efficiency: Paginated queries help in efficiently loading data, especially for large datasets, by fetching only what's needed Queries that scale (https://stack.convex.dev/queries-that-scale#2-splitting-up-the-work-with-pagination-and-limits).

Here's a basic example of how you might structure a paginated query with filters:

export const listWithFilters = query({
  args: { paginationOpts: paginationOptsValidator, filter: v.string() },
  handler: async (ctx, args) => {
    return await ctx.db
      .query("yourTable")
      .filter((q) => q.eq(q.field("someField"), args.filter))
      .order("desc")
      .paginate(args.paginationOpts);
  },
});

You can then use this query in your React component with the usePaginatedQuery hook, conditionally based on whether pagination is needed:

const { results, status, loadMore } = usePaginatedQuery(
  api.yourModule.listWithFilters,
  { filter: "someValue" },
  { initialNumItems: 10 }
);

This approach gives you the flexibility to handle both paginated and non-paginated scenarios while leveraging Convex's built-in pagination features.

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@long wigeon Kapa.ai is still learning and improving, please let me know how I did by reacting below.

[long wigeon]

@shell rain I am using a custom query to make data something more stable so I don't get loading blinks when filtering:

import { useRef } from 'react';
import { useQuery } from 'convex/react';

//Not fully reactive query fn => Ideal when filtering data
export const useStableQuery = ((name, ...args) => {
const result = useQuery(name, ...args);
const stored = useRef(result);

if (result !== undefined) stored.current = result;

return stored.current;
}) as typeof useQuery;

Could it be applied to this?

[shell rain]

Let me check the knowledge base for you again. One moment! :books:

---

Yes, you can apply a similar approach to create a stable version of the usePaginatedQuery hook. This technique, known as useStableQuery, is indeed useful for reducing loading blinks when filtering data, as described in the Help, my app is overreacting! (https://stack.convex.dev/help-my-app-is-overreacting#impacting-how-the-querys-reacting) article.

Here's how you can adapt this concept for usePaginatedQuery:

import { useRef } from 'react';
import { usePaginatedQuery } from 'convex/react';

export const useStablePaginatedQuery = ((name, ...args) => {
  const result = usePaginatedQuery(name, ...args);
  const stored = useRef(result);

  // If new data is still loading, wait and do nothing
  // If data has finished loading, use the ref to store it
  if (result.status !== 'LoadingMore') {
    stored.current = result;
  }

  return stored.current;
}) as typeof usePaginatedQuery;

This implementation is based on the example provided in the Help, my app is overreacting! (https://stack.convex.dev/help-my-app-is-overreacting#what-about-pagination-is-that-a-complication) article, which specifically addresses pagination.

The key differences from your useStableQuery implementation are:

1. It uses usePaginatedQuery instead of useQuery.
2. It checks for the LoadingMore status rather than undefined to determine when not to update the results.

You can use this useStablePaginatedQuery in your components just like you would use usePaginatedQuery, but it will provide more stable behavior when filtering or changing query parameters.

Remember that this approach trades off some reactivity for stability. It will reduce flickering, but it may also slightly delay updates in some cases. Use it when the improved user experience from reduced flickering outweighs the need for immediate updates.

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@long wigeon Kapa.ai is still learning and improving, please let me know how I did by reacting below.

[long wigeon]

@shell rain This is my implementation:
export const getProjectTasks = query({
args: {
teamId: v.id('teams'),
projectId: v.id('projects'),
filters: v.object({
status: v.optional(Tasks.withoutSystemFields.status),
priority: v.optional(Tasks.withoutSystemFields.priority),
label: v.optional(Tasks.withoutSystemFields.label),
}),
},
handler: async (ctx, args) => {
const {
teamId,
projectId,
filters: { status, priority, label },
} = args;
await isMember(ctx, teamId);

let query = ctx.db
  .query('tasks')
  .withIndex('by_teamId_projectId', q =>
    q.eq('teamId', teamId).eq('projectId', projectId)
  );

if (status) query = query.filter(q => q.eq(q.field('status'), status));
if (priority)
  query = query.filter(q => q.eq(q.field('priority'), priority));
if (label) query = query.filter(q => q.eq(q.field('label'), label));

const tasks = await Promise.all(
  (await query.order('desc').collect()).map(async task => ({
    ...task,
    assignee: task.assignee ? await ctx.db.get(task.assignee) : null,
    label: task.label ? await ctx.db.get(task.label) : null,
  }))
);
return tasks;

},
});

But I am i little bit confused

[shell rain]

Let me check the knowledge base for you again. One moment! :books:

---

Thank you for sharing your implementation. I understand you're feeling a bit confused about it. Let's break down your query and discuss how it relates to pagination and the stable query approach we discussed earlier.

Your current implementation is a regular Convex query that fetches all tasks for a given project, applies filters, and then collects all results at once. Here are a few observations and suggestions:

1. Pagination: Your current query doesn't use pagination. It fetches all tasks that match the criteria using .collect(). For large datasets, this could potentially lead to performance issues. If you want to implement pagination, you should use .paginate() instead of .collect() Paginated Queries (https://docs.convex.dev/database/pagination#writing-paginated-query-functions).

2. Filtering: Your filtering approach is correct and efficient. You're building the query dynamically based on the provided filters.

3. Data Fetching: You're using Promise.all() to fetch additional data for each task. While this works, it could potentially lead to many separate database queries, which might not be optimal for performance.

To implement pagination and make this query work with the useStablePaginatedQuery we discussed earlier, you could modify it like this:

export const getProjectTasks = query({
  args: {
    teamId: v.id('teams'),
    projectId: v.id('projects'),
    filters: v.object({
      status: v.optional(Tasks.withoutSystemFields.status),
      priority: v.optional(Tasks.withoutSystemFields.priority),
      label: v.optional(Tasks.withoutSystemFields.label),
    }),
    paginationOpts: paginationOptsValidator,
  },
  handler: async (ctx, args) => {
    const {
      teamId,
      projectId,
      filters: { status, priority, label },
      paginationOpts,
    } = args;
    await isMember(ctx, teamId);

    let query = ctx.db
      .query('tasks')
      .withIndex('by_teamId_projectId', q =>
        q.eq('teamId', teamId).eq('projectId', projectId)
      );

    if (status) query = query.filter(q => q.eq(q.field('status'), status));
    if (priority) query = query.filter(q => q.eq(q.field('priority'), priority));
    if (label) query = query.filter(q => q.eq(q.field('label'), label));

    const paginatedResult = await query.order('desc').paginate(paginationOpts);

    const tasksWithDetails = await Promise.all(
      paginatedResult.page.map(async task => ({
        ...task,
        assignee: task.assignee ? await ctx.db.get(task.assignee) : null,
        label: task.label ? await ctx.db.get(task.label) : null,
      }))
    );

    return {
      ...paginatedResult,
      page: tasksWithDetails,
    };
  },
});

This modified version:

1. Accepts paginationOpts as an argument.
2. Uses .paginate() instead of .collect().
3. Applies the additional data fetching only to the paginated results.

You can then use this with the useStablePaginatedQuery hook in your React component:

const { results, status, loadMore } = useStablePaginatedQuery(
  api.tasks.getProjectTasks,
  { teamId, projectId, filters, paginationOpts: { initialNumItems: 10 } }
);

This approach combines pagination with your existing filtering logic and should work well with the stable query pattern to reduce loading blinks Paginated Queries (https://docs.convex.dev/api/modules/react#usepaginatedquery).

Remember, while this approach can improve the user experience by reducing flickering, it may slightly delay updates in some cases. Make sure this trade-off aligns with your application's needs.

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@long wigeon Kapa.ai is still learning and improving, please let me know how I did by reacting below.

[long wigeon]

@shell rain Now after implementing everything I get the loading blink back

[shell rain]

Let me check the knowledge base for you again. One moment! :books:

---

I apologize for the confusion. It seems that despite implementing the useStablePaginatedQuery, you're still experiencing loading blinks. Let's troubleshoot this issue.

The loading blink you're experiencing could be due to a few reasons:

1. The useStablePaginatedQuery might not be implemented correctly.
2. The component might be re-rendering for reasons other than query updates.
3. The pagination logic might be resetting the query state.

Let's address these possibilities:

1. First, double-check your useStablePaginatedQuery implementation. It should look similar to this example from the Convex documentation (https://stack.convex.dev/help-my-app-is-overreacting#what-about-pagination-is-that-a-complication):

export const useStablePaginatedQuery = ((name, ...args) => {
  const result = usePaginatedQuery(name, ...args);
  const stored = useRef(result);

  if (result.status !== 'LoadingMore') {
    stored.current = result;
  }

  return stored.current;
}) as typeof usePaginatedQuery;

2. Ensure that your component isn't re-rendering unnecessarily. You might want to use React's useCallback or useMemo hooks to memoize values and functions that don't need to change on every render.

3. Check how you're handling filter changes. If you're resetting the pagination state on every filter change, it might cause a loading blink. Instead, you could keep the current results while loading the new filtered results.

If you've verified these points and are still seeing loading blinks, you might need to implement a more aggressive caching strategy. Here's an approach you could try, based on the caching strategy described in the Convex helpers documentation (https://github.com/get-convex/convex-helpers/blob/main/packages/convex-helpers/README.md#query-caching):

import { useRef, useCallback } from 'react';
import { usePaginatedQuery } from 'convex/react';

export function useStablePaginatedQuery(queryName, ...args) {
  const resultRef = useRef();
  const argsRef = useRef();

  const result = usePaginatedQuery(queryName, ...args);

  if (
    result.status !== 'LoadingMore' &&
    JSON.stringify(args) !== JSON.stringify(argsRef.current)
  ) {
    resultRef.current = result;
    argsRef.current = args;
  }

  const loadMore = useCallback(
    async (numItems) => {
      const newResult = await result.loadMore(numItems);
      if (newResult.status !== 'LoadingMore') {
        resultRef.current = newResult;
      }
      return newResult;
    },
    [result.loadMore]
  );

  return { ...resultRef.current, loadMore };
}

This implementation caches the result and only updates it when the query arguments change or when new data is successfully loaded. It should help reduce loading blinks even further.

If you're still experiencing issues after trying these solutions, it might be helpful to provide more details about your specific implementation and when exactly the loading blinks occur. This would allow for a more targeted troubleshooting approach.

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@long wigeon Kapa.ai is still learning and improving, please let me know how I did by reacting below.

[long wigeon]

@shell rain I'll send you all my code:

export const useStablePaginatedQuery = ((name, ...args) => {
const result = usePaginatedQuery(name, ...args);
const stored = useRef(result);

if (result.status !== 'LoadingMore') {
stored.current = result;
}

return stored.current;
}) as typeof usePaginatedQuery;

export const getProjectTasks = query({
args: {
teamId: v.id('teams'),
projectId: v.id('projects'),
filters: v.object({
status: v.optional(Tasks.withoutSystemFields.status),
priority: v.optional(Tasks.withoutSystemFields.priority),
label: v.optional(Tasks.withoutSystemFields.label),
}),
paginationOpts: paginationOptsValidator,
},
handler: async (ctx, args) => {
const {
teamId,
projectId,
filters: { status, priority, label },
paginationOpts,
} = args;
await isMember(ctx, teamId);

let query = ctx.db
  .query('tasks')
  .withIndex('by_teamId_projectId', q =>
    q.eq('teamId', teamId).eq('projectId', projectId)
  );

if (status) query = query.filter(q => q.eq(q.field('status'), status));
if (priority)
  query = query.filter(q => q.eq(q.field('priority'), priority));
if (label) query = query.filter(q => q.eq(q.field('label'), label));

const paginatedResult = await query.order('desc').paginate(paginationOpts);

const tasksWithDetails = await Promise.all(
  paginatedResult.page.map(async task => ({
    ...task,
    assignee: task.assignee ? await ctx.db.get(task.assignee) : null,
    label: task.label ? await ctx.db.get(task.label) : null,
  }))
);

return {
  ...paginatedResult,
  page: tasksWithDetails,
};

},
});

const tasks = useStablePaginatedQuery(
api.tasks.getProjectTasks,
{
teamId,
projectId,
filters: {
priority: priority || undefined,
status: status || undefined,
},
},
{ initialNumItems: 10 }
);

[shell rain]

Let me check the knowledge base for you again. One moment! :books:

---

Thank you for providing your code. After reviewing it, I can see that your implementation is mostly correct, but there might be a few issues causing the loading blink. Let's address them:

1. Your useStablePaginatedQuery implementation looks correct and matches the recommended approach from the Convex documentation (https://stack.convex.dev/help-my-app-is-overreacting#what-about-pagination-is-that-a-complication).

2. In your getProjectTasks query, you're using paginate correctly, which is good for handling large datasets efficiently.

3. The issue might be in how you're using useStablePaginatedQuery in your component. The loading blink could be occurring when the filters change. Here's a potential solution:

const { results, status, loadMore } = useStablePaginatedQuery(
  api.tasks.getProjectTasks,
  {
    teamId,
    projectId,
    filters: {
      priority: priority || undefined,
      status: status || undefined,
    },
    paginationOpts: { numItems: 10 }
  }
);

Note that I changed initialNumItems to numItems in the paginationOpts. This is because usePaginatedQuery expects numItems in the paginationOpts object UsePaginatedQueryResult (https://docs.convex.dev/api/modules/react#usepaginatedqueryresult).

4. If you're still seeing loading blinks, it might be because the component is re-rendering when priority or status changes. To mitigate this, you can memoize the filters object:

import { useMemo } from 'react';

// ...

const filters = useMemo(() => ({
  priority: priority || undefined,
  status: status || undefined,
}), [priority, status]);

const { results, status, loadMore } = useStablePaginatedQuery(
  api.tasks.getProjectTasks,
  {
    teamId,
    projectId,
    filters,
    paginationOpts: { numItems: 10 }
  }
);

5. Lastly, ensure that teamId and projectId are not changing frequently, as changes to these would trigger a new query and potentially cause a loading blink.

If you're still experiencing loading blinks after these changes, it might be helpful to implement a more aggressive caching strategy as mentioned in the previous response. However, the current implementation should theoretically reduce most loading blinks.

Remember, some loading indicators might still be necessary, especially when changing filters, to provide feedback to the user that their action is being processed. The goal is to reduce unnecessary flashes, not eliminate all loading states.

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@long wigeon Kapa.ai is still learning and improving, please let me know how I did by reacting below.

[long wigeon]

@shell rain I belive I found the potencial problem.
When I apply a filter the tasks objects looks like this:
results: Array(0), status: 'LoadingFirstPage', isLoading: true, loadMore: ƒ
And after a bit the results have obejcts and the status is exahusted

[shell rain]

Let me check the knowledge base for you again. One moment! :books:

---

I see. You've identified an important aspect of how usePaginatedQuery works. Let's break down what's happening and how we can address it:

1. When you apply a filter, the query is essentially reset, which is why you're seeing status: 'LoadingFirstPage' and an empty results array. This is expected behavior for usePaginatedQuery when the query parameters change UsePaginatedQueryResult (https://docs.convex.dev/api/modules/react#usepaginatedqueryresult).

2. After the new data is loaded, the status changes to 'Exhausted' if all available data has been fetched.

This behavior is causing the loading blink you're experiencing. To mitigate this, we need to modify our useStablePaginatedQuery to handle this case. Here's an improved version:

import { useRef, useEffect } from 'react';
import { usePaginatedQuery } from 'convex/react';

export const useStablePaginatedQuery = ((name, ...args) => {
  const result = usePaginatedQuery(name, ...args);
  const stored = useRef(result);

  useEffect(() => {
    if (result.status !== 'LoadingFirstPage' && result.status !== 'LoadingMore') {
      stored.current = result;
    }
  }, [result]);

  return stored.current;
}) as typeof usePaginatedQuery;

This implementation:

1. Uses useEffect to update the stored result, which ensures we're not updating during render.
2. Only updates the stored result when we're not in a loading state (either 'LoadingFirstPage' or 'LoadingMore').
3. Keeps the previous results while loading, which should prevent the loading blink.

When using this hook in your component, you might want to add a separate loading indicator for when filters are applied:

const { results, status, isLoading } = useStablePaginatedQuery(
  api.tasks.getProjectTasks,
  {
    teamId,
    projectId,
    filters,
    paginationOpts: { numItems: 10 }
  }
);

// In your render method:
if (isLoading && results.length === 0) {
return <LoadingIndicator />;
}

return (
<>
{results.map(task => <TaskItem key={task._id} task={task} />)}
{isLoading && <SmallLoadingIndicator />}
</>
);

This approach should significantly reduce the loading blink while still providing feedback to the user when new data is being fetched. The main list will remain stable while filters are applied, and a smaller loading indicator can show that the query is being updated.

Remember, some level of loading indication is often necessary for a good user experience, especially when applying filters. The goal is to make these transitions as smooth as possible while still keeping the user informed about the state of their data **UI patterns** (<https://docs.convex.dev/production/best-practices/#ui-patterns>).
----------------------
Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
----------------------

@long wigeon Kapa.ai is still learning and improving, please let me know how I did by reacting below.

[long wigeon]

@shell rain Im still getting the blinks. I don't really know what is going on

[shell rain]

Let me check the knowledge base for you again. One moment! :books:

---

I apologize for the persistent issue you're experiencing. It's clear that the loading blinks are still occurring despite our previous attempts to resolve them. Let's take a step back and consider a different approach.

Given that you're still experiencing blinks, it might be worth trying a more aggressive caching strategy. Here's an alternative implementation of useStablePaginatedQuery that might help:

import { useRef, useCallback } from 'react';
import { usePaginatedQuery } from 'convex/react';

export function useStablePaginatedQuery(queryName, ...args) {
  const resultRef = useRef();
  const argsRef = useRef();

  const result = usePaginatedQuery(queryName, ...args);

  if (
    (result.status === 'CanLoadMore' || result.status === 'Exhausted') &&
    JSON.stringify(args) !== JSON.stringify(argsRef.current)
  ) {
    resultRef.current = result;
    argsRef.current = args;
  }

  const loadMore = useCallback(
    async (numItems) => {
      const newResult = await result.loadMore(numItems);
      if (newResult.status !== 'LoadingMore') {
        resultRef.current = newResult;
      }
      return newResult;
    },
    [result.loadMore]
  );

  return resultRef.current || { ...result, loadMore };
}

This implementation:

1. Caches the result and only updates it when the query arguments change and the new data is fully loaded.
2. Returns the cached result if available, otherwise returns the current result.
3. Provides a custom loadMore function that updates the cache when new data is loaded.

When using this in your component, you might want to add some additional checks:

const { results, status, isLoading } = useStablePaginatedQuery(
  api.tasks.getProjectTasks,
  {
    teamId,
    projectId,
    filters,
    paginationOpts: { numItems: 10 }
  }
);

// In your render method:
if (!results) {
return <LoadingIndicator />;
}

return (
<>
{results.length > 0 ? (
results.map(task => <TaskItem key={task._id} task={task} />)
) : (
<NoTasksMessage />
)}
{isLoading && <SmallLoadingIndicator />}
</>
);

If you're still experiencing blinks after this, the issue might be more complex than we initially thought. It could be related to how your component is structured or how other parts of your application are interacting with this query.

At this point, it might be helpful to:

1. Use React DevTools to monitor your component re-renders and state changes.
2. Add console logs in your component and in the `useStablePaginatedQuery` hook to track when and how the data is changing.
3. Consider posting your issue on the **Convex Discord community** (<https://discord.com/channels/1019350475847499849/1019350478817079338>) for more specialized help.

Remember, while we're trying to minimize loading blinks, some level of loading indication is often necessary for a good user experience, especially when applying filters or pagination **UI patterns** (<https://docs.convex.dev/production/best-practices/#ui-patterns>). The goal is to make these transitions as smooth as possible while still keeping the user informed about the state of their data.
----------------------
Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:
----------------------

@long wigeon Kapa.ai is still learning and improving, please let me know how I did by reacting below.

[long wigeon]

@shell rain One last question. If I want to use one of my paginated queries somewhere where I don't need the pagination but my convex function has the .paginate, is there any way to skip that?

[shell rain]

Let me check the knowledge base for you again. One moment! :books:

---

Yes, there is a way to use a paginated query without actually paginating the results. You can achieve this by using the regular useQuery hook instead of usePaginatedQuery and setting a large numItems value in the paginationOpts. This will effectively fetch all the results at once, bypassing the pagination mechanism.

Here's how you can do it:

import { useQuery } from 'convex/react';
import { api } from '../convex/_generated/api';

// In your component
const allResults = useQuery(api.yourModule.yourPaginatedQuery, {
  // Your other args here
  paginationOpts: { numItems: 1000000 } // A very large number
});

By setting numItems to a very large number, you're essentially telling Convex to fetch all the results in one go. However, please keep in mind a few important points:

1. This approach may not be efficient for very large datasets, as it will fetch all the data at once Queries that scale (https://stack.convex.dev/queries-that-scale#2-splitting-up-the-work-with-pagination-and-limits).

2. Convex has a limit on how many documents can be read in a single transaction. If your dataset exceeds this limit, the query might fail Paginated Queries (https://docs.convex.dev/database/pagination#writing-paginated-query-functions).

3. This method will still return the results in the paginated format (i.e., { page: [...], isDone: true, continueCursor: null }), so you'll need to access the page property to get your results.

If you find yourself frequently needing both paginated and non-paginated versions of the same query, you might want to consider creating two separate query functions on the backend - one with pagination and one without. This would allow you to optimize each query for its specific use case.

Remember, the best approach depends on your specific use case and the size of your dataset. Always consider the performance implications when fetching large amounts of data.

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@long wigeon Kapa.ai is still learning and improving, please let me know how I did by reacting below.

[long wigeon]

@shell rain Woukld it be possibel to combine this two approaches?? One is implementing proper pagination adn the other is for stable querying:

import { useRef } from 'react';
import { usePaginatedQuery } from 'convex/react';

//Not fully reactive query fn => Ideal when filtering data
export const useStablePaginatedQuery = ((name, ...args) => {
const result = usePaginatedQuery(name, ...args);
const stored = useRef(result);

if (result.status !== 'LoadingMore' && result.status !== 'LoadingFirstPage')
stored.current = result;

return stored.current;
}) as typeof usePaginatedQuery;

[shell rain]

Let me check the knowledge base for you again. One moment! :books:

---

Yes, it is possible to combine the approaches for proper pagination and stable querying. In fact, the code you've provided is already a good start towards achieving this goal. Let's refine it a bit to make it more robust:

import { useRef, useCallback } from 'react';
import { usePaginatedQuery } from 'convex/react';

export const useStablePaginatedQuery = ((name, ...args) => {
  const result = usePaginatedQuery(name, ...args);
  const stored = useRef(result);

  if (result.status !== 'LoadingMore' && result.status !== 'LoadingFirstPage') {
    stored.current = result;
  }

  const loadMore = useCallback(
    async (numItems: number) => {
      const newResult = await result.loadMore(numItems);
      if (newResult.status !== 'LoadingMore' && newResult.status !== 'LoadingFirstPage') {
        stored.current = newResult;
      }
      return newResult;
    },
    [result.loadMore]
  );

  return {
    ...stored.current,
    loadMore,
  };
}) as typeof usePaginatedQuery;

This implementation combines proper pagination with stable querying by:

1. Using usePaginatedQuery to handle pagination Paginated Queries (https://docs.convex.dev/api/modules/react#usepaginatedquery).
2. Storing the result in a ref to maintain stability across renders, which helps reduce loading blinks Help, my app is overreacting! (https://stack.convex.dev/help-my-app-is-overreacting#what-about-pagination-is-that-a-complication).
3. Only updating the stored result when it's not in a loading state.
4. Providing a custom loadMore function that updates the stored result when new data is loaded, ensuring that pagination works correctly with the stable query approach.

This combined approach should give you the benefits of both proper pagination and stable querying:

• It allows you to load data in pages, which is efficient for large datasets.
• It reduces loading blinks when filters or other query parameters change.
• It maintains the reactive nature of Convex queries while providing a more stable UI experience.

When using this hook in your component, you can handle both pagination and filtering:

const { results, status, isLoading, loadMore } = useStablePaginatedQuery(
  api.tasks.getProjectTasks,
  {
    teamId,
    projectId,
    filters,
    paginationOpts: { numItems: 10 }
  }
);

// In your render method:
return (
  <>
    {results?.map(task => <TaskItem key={task._id} task={task} />)}
    {status === 'CanLoadMore' && (
      <button onClick={() => loadMore(10)}>Load More</button>
    )}
    {isLoading && <SmallLoadingIndicator />}
  </>
);

This approach should provide a smooth user experience with proper pagination and reduced loading blinks. Remember to always consider the specific needs of your application and adjust the implementation accordingly.

UI patterns (https://docs.convex.dev/production/best-practices/#ui-patterns)

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon:

@long wigeon Kapa.ai is still learning and improving, please let me know how I did by reacting below.

[long wigeon]

@shell rain the approach you are giving me, doesn;'t have pagination (next-prev)

[shell rain]

Let me check the knowledge base for you again. One moment! :books:

---

You're right, and I apologize for the oversight. The approach I provided earlier focuses on infinite scrolling (loading more items) rather than traditional pagination with next and previous buttons. Let's modify the implementation to support both next-prev pagination and stable querying.

Here's an updated version that includes next-prev pagination:

import { useRef, useCallback, useState } from 'react';
import { usePaginatedQuery } from 'convex/react';

export const useStablePaginatedQuery = ((name, ...args) => {
  const [page, setPage] = useState(1);
  const itemsPerPage = args[1]?.paginationOpts?.numItems || 10;

  const result = usePaginatedQuery(name, {
    ...args[0],
    paginationOpts: { ...args[1]?.paginationOpts, numItems: page * itemsPerPage }
  });
  const stored = useRef(result);

  if (result.status !== 'LoadingMore' && result.status !== 'LoadingFirstPage') {
    stored.current = result;
  }

  const currentPageResults = stored.current?.results?.slice((page - 1) * itemsPerPage, page * itemsPerPage);

  const nextPage = useCallback(() => {
    if (stored.current?.status === 'CanLoadMore' || (stored.current?.results?.length || 0) > page * itemsPerPage) {
      setPage(prev => prev + 1);
    }
  }, [page, stored.current]);

  const prevPage = useCallback(() => {
    if (page > 1) {
      setPage(prev => prev - 1);
    }
  }, [page]);

  return {
    results: currentPageResults,
    status: stored.current?.status,
    isLoading: stored.current?.isLoading,
    nextPage,
    prevPage,
    page,
    hasNextPage: stored.current?.status === 'CanLoadMore' || (stored.current?.results?.length || 0) > page * itemsPerPage,
    hasPrevPage: page > 1
  };
}) as typeof usePaginatedQuery;

This implementation:

1. Maintains the stability of the query to reduce loading blinks Help, my app is overreacting! (https://stack.convex.dev/help-my-app-is-overreacting#what-about-pagination-is-that-a-complication).
2. Implements client-side pagination on top of Convex's cursor-based pagination Paginated Queries (https://docs.convex.dev/database/pagination).
3. Provides nextPage and prevPage functions for traditional pagination navigation.
4. Calculates hasNextPage and hasPrevPage to help with UI rendering.

You can use this hook in your component like this:

const { 
  results, 
  status, 
  isLoading, 
  nextPage, 
  prevPage, 
  page, 
  hasNextPage, 
  hasPrevPage 
} = useStablePaginatedQuery(
  api.tasks.getProjectTasks,
  {
    teamId,
    projectId,
    filters
  },
  { paginationOpts: { numItems: 10 } }
);

// In your render method:
return (
  <>
    {results?.map(task => <TaskItem key={task._id} task={task} />)}
    <div>
      <button onClick={prevPage} disabled={!hasPrevPage}>Previous</button>
      <span>Page {page}</span>
      <button onClick={nextPage} disabled={!hasNextPage}>Next</button>
    </div>
    {isLoading && <SmallLoadingIndicator />}
  </>
);

This approach combines stable querying with traditional next-prev pagination, providing a more familiar pagination interface while still leveraging Convex's efficient cursor-based pagination under the hood.

Remember to adjust the itemsPerPage value according to your needs, and consider the trade-offs between client-side and server-side pagination based on your specific use case and data size Queries that scale (https://stack.convex.dev/queries-that-scale#2-splitting-up-the-work-with-pagination-and-limits).

Note: you can ask me a follow up question by @ mentioning me again :speech_balloon: