Cursor-based pagination in GraphQL - Step-by-Step Execution

Concept Flow - Cursor-based pagination

Start Query with cursor=null

↓

Fetch first N items after cursor

↓

Return items + new cursor

↓

User requests next page with new cursor

↓

Repeat fetch with updated cursor

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Stop when no more items

Cursor-based pagination fetches a set number of items after a given cursor, returning a new cursor for the next page until no more items remain.

Execution Sample

GraphQL

query {
  posts(first: 3, after: "cursor123") {
    edges {
      node { id title }
      cursor
    }
    pageInfo { hasNextPage endCursor }
  }
}

Fetch 3 posts after the cursor 'cursor123', returning posts and info for next page.

Execution Table

Step	Input Cursor	Action	Items Fetched	New Cursor	Has Next Page
1	null	Fetch first 3 posts from start	[Post1, Post2, Post3]	cursor3	true
2	cursor3	Fetch next 3 posts after cursor3	[Post4, Post5, Post6]	cursor6	true
3	cursor6	Fetch next 3 posts after cursor6	[Post7]	cursor7	false
4	cursor7	No more posts after cursor7	[]	null	false

💡 No more items after cursor7, pagination ends.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4
input_cursor	null	cursor3	cursor6	cursor7	null
items_fetched	[]	[Post1, Post2, Post3]	[Post4, Post5, Post6]	[Post7]	[]
has_next_page	false	true	true	false	false

Key Moments - 3 Insights

Why do we use a cursor instead of page numbers?

Cursor points to a specific item, so pagination is stable even if data changes. See execution_table steps 1-3 where cursor moves forward instead of page numbers.

What happens if the cursor is null at the start?

It means fetch from the beginning. Execution_table step 1 shows input_cursor null fetches first items.

Why does the last fetch return fewer items?

Because fewer items remain than requested. Step 3 fetches only one post, showing end of data.

Visual Quiz - 3 Questions

Look at the execution_table, what is the input_cursor at Step 2?

A cursor6

B null

C cursor3

D cursor7

💡 Hint

Check the 'Input Cursor' column at Step 2 in execution_table.

At which step does hasNextPage become false?

A Step 1

B Step 3

C Step 2

D Step 4

💡 Hint

Look at the 'Has Next Page' column in execution_table to find when it changes to false.

If we change the first fetch to 5 items, how would items_fetched at Step 1 change?

A It would fetch 5 posts instead of 3

B It would fetch 3 posts as before

C It would fetch no posts

D It would fetch all posts

💡 Hint

Refer to the code sample where 'first: 3' controls number of items fetched.

Concept Snapshot

Cursor-based pagination:
- Uses a cursor to mark position in data
- Query fetches items after cursor
- Returns items + new cursor for next page
- Stable with data changes
- Stops when no more items

Full Transcript

Cursor-based pagination is a way to get data in chunks using a cursor that points to a specific item. We start with no cursor to get the first items. Each response gives a new cursor to fetch the next chunk. This continues until no more items are left. This method is better than page numbers because it handles data changes smoothly. The example query fetches posts after a cursor, returning edges with nodes and cursors, plus page info. The execution table shows how the cursor moves forward and when pagination ends.