Skip to content

Latest commit

 

History

History
106 lines (84 loc) · 2.82 KB

paging.md

File metadata and controls

106 lines (84 loc) · 2.82 KB
Raw

Paging

Manual Paging

For more information see: https://graphql.org/learn/pagination/

Many GraphQL fields can be paged. These fields typically define at least four paging parameters:

Parameter Description
first Pages forward N results at a time
after The end cursor of the previous page
last Pages backwards N results at a time
before The start cursor of the previous page

In addition, these fields produce a Connection object which contains a list of edges and nodes, together with a totalCount and a pageInfo object.

To run a paged query, you would write code like this:

// Read a page of issues from a Repsitory.
var query = new Query()
    .Repository("octokit", "octokit.net")
    .Issues(first: 100, after: Var("after"))
    .Select(connection => new
    {
        connection.PageInfo.EndCursor,
        connection.PageInfo.HasNextPage,
        connection.TotalCount,
        Items = connection.Nodes.Select(issue => new
        {
            issue.Number,
            issue.Title,
        }).ToList(),
    }).Compile();

// For the first page, set `after` to null.
var vars = new Dictionary<string, object>
{
    { "after", null },
};

// Read the first page.
var result = await connection.Run(query, vars);

// If there are more pages, set `after` to the end cursor.
vars["after"] = result.HasNextPage ? result.EndCursor : null;

while (vars["after"] != null)
{
    // Read the next page.
    var page = await connection.Run(query, vars);

    // Add the results from the page to the result.
    result.Items.AddRange(page.Items);

    // If there are more pages, set `after` to the end cursor.
    vars["after"] = page.HasNextPage ? page.EndCursor : null;
}

As you can see, it's rather complex for such a common task, and it gets even more complicated if you need to do nested paging.

Thankfully, there is an easier way - auto-paging!

Auto-Paging

With auto-paging, the above query can be rewritten as:

var query = new Query()
    .Repository("octokit", "octokit.net")
    .Issues()
    .AllPages() // Auto-pages Issues
    .Select(issue => new
    {
        issue.Number,
        issue.Title,
    }).Compile();

var result = await connection.Run(query);

To enable auto-paging, you simply call .AllPages() where you would usually call .Nodes. Because Octokit.GraphQL.net understands your query, it can rewrite the query to automatically do the paging for you.

This also works for nested queries:

var query = new Query()
    .Repository("octokit", "octokit.net")
    .Issues()
    .AllPages() // Auto-pages Issues
    .Select(issue => new
    {
        issue.Id,
        Comments = issue
            .Comments(null, null, null, null)
            .AllPages() // Auto-pages Issue Comments
            .Select(comment => comment.Body)
            .ToList(),
    });