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Arguments

By · Reviewed & last updated · Part of GraphQL Tutorial

Arguments customise a field’s behaviour: limit results, filter, paginate, sort. Define them in the schema with types and defaults; access them as the second resolver argument.

Filter, paginate, default, validate

EXAMPLE
# Schema — typed arguments with defaults
type Query {
    posts(
        first:    Int    = 20
        after:    String                            # cursor
        status:   PostStatus
        authorId: ID
        search:   String
    ): PostConnection!
}

enum PostStatus { DRAFT PUBLISHED ARCHIVED }

type PostConnection {
    edges:    [PostEdge!]!
    pageInfo: PageInfo!
}

type PostEdge {
    cursor: String!
    node:   Post!
}

type PageInfo {
    endCursor:   String
    hasNextPage: Boolean!
}

# Resolver — destructure args
Query: {
    posts: async (_, { first, after, status, authorId, search }, { db }) => {
        // Validate / clamp
        const take = Math.min(first ?? 20, 100);

        const where = {
            status,
            authorId,
            title: search ? { contains: search, mode: 'insensitive' } : undefined,
            id: after ? { gt: decodeCursor(after) } : undefined,
        };

        const rows = await db.posts.findMany({
            where,
            take: take + 1,                  // fetch one extra to detect next page
            orderBy: { id: 'asc' },
        });

        const hasNextPage = rows.length > take;
        const edges = rows.slice(0, take).map(p => ({
            cursor: encodeCursor(p.id),
            node:   p,
        }));

        return {
            edges,
            pageInfo: { endCursor: edges.at(-1)?.cursor, hasNextPage },
        };
    },
},

Why it matters

Always cap pagination args server-side. A client asking for first: 1_000_000 shouldn’t take your DB down — clamp to a sensible max in the resolver.

Tip: Tweak the snippet with Try it Yourself », then sit the quiz at the bottom of the page.

Example

Example
type Query { user(id: ID!): User }
Try it Yourself »

Discussion

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