Pagination in apollo-graphql server - graphql

Question

I want to implement cursor based pagination in Apollo graphql server. I have prepared schema with pagination requirement. But i am stuck at resolver side.
Here is my schema
const typeDefinitions = `
input CreateDeveloperInput {
# An arbitrary string value with no semantic meaning. Will be included in the
# payload verbatim. May be used to track mutations by the client.
clientMutationId: String
developer: DeveloperInput!
}
type CreateDeveloperPayload {
clientMutationId: String
developerEdge(orderBy: DevelopersOrderBy = PRIMARY_KEY_ASC): DevelopersEdge
query: Query
}
input DeleteDeveloperByIdInput {
# An arbitrary string value with no semantic meaning. Will be included in the
# payload verbatim. May be used to track mutations by the client.
clientMutationId: String
id: Int!
}
input DeleteDeveloperInput {
clientMutationId: String
nodeId: ID!
}
type DeleteDeveloperPayload {
clientMutationId: String
developer: Developer
deletedDeveloperId: ID
# Our root query field type. Allows us to run any query from our mutation payload.
query: Query
}
type Developer implements Node {
nodeId: ID!
id: Int!
name: String!
place: String
salary: Int
joiningDate: String
}
input DeveloperCondition {
id: Int
name: String
place: String
salary: Int
joiningDate: String
}
input DeveloperInput {
id: Int
name: String!
place: String
salary: Int
joiningDate: String
}
input DeveloperPatch {
id: Int
name: String
place: String
salary: Int
joiningDate: String
}
type DevelopersConnection {
# Information to aid in pagination.
pageInfo: PageInfo!
totalCount: Int
edges: [DevelopersEdge]
nodes: [Developer!]
}
type DevelopersEdge {
# A cursor for use in pagination.
cursor: String
node: Developer!
}
enum DevelopersOrderBy {
PRIMARY_KEY_ASC
PRIMARY_KEY_DESC
NATURAL
ID_ASC
ID_DESC
NAME_ASC
NAME_DESC
PLACE_ASC
PLACE_DESC
SALARY_ASC
SALARY_DESC
JOINING_DATE_ASC
JOINING_DATE_DESC
}
# The root mutation type which contains root level fields which mutate data.
interface Node {
# A globally unique identifier. Can be used in various places throughout the system to identify this single value.
nodeId: ID!
}
# Information about pagination in a connection.
type PageInfo {
# When paginating forwards, are there more items?
hasNextPage: Boolean!
# When paginating backwards, are there more items?
hasPreviousPage: Boolean!
# When paginating backwards, the cursor to continue.
startCursor: String
# When paginating forwards, the cursor to continue.
endCursor: String
}
# The root query type which gives access points into the data universe.
type Query implements Node {
allDevelopers(
# Read all values in the set before (above) this cursor.
before: String,
# Read all values in the set after (below) this cursor.
after: String, first: Int, last: Int, offset: Int,
# A condition to be used in determining which values should be returned by the collection.
condition: DeveloperCondition): DevelopersConnection
# Exposes the root query type nested one level down. This is helpful for Relay 1
# which can only query top level fields if they are in a particular form.
nodeId: ID!
}
schema {
query: Query
}
`;
export default [typeDefinitions];
Is it possible to resolve in resolvers? If yes, can any one please tell me how to implement it

Answer 1

If you're using Mongo and Mongoose with Apollo Express GraphQL I have found three ways to do pagination:
You can create a cursor field on your schema and implement your resolver with the pagination logic, but I don't recommend this method if you have a complex schema that contain unions, interfaces and different nested objects on the type, but if you want to implement it by yourself here's the reference
You can use a module which will nest your Mongoose model and provide you an pagination interface, but this requires a few changes on your schema and resolvers, more work then the third method
You can use sort, skip and limit from Mongo / Mongoose, but if you do this by yourself you can find some issues, e.g if the document was sorted by a date key which can have different documents with the same date it can duplicate documents and mess up with your pagination, so I recommend that you install a pagination plugin on your Mongoose schema and use it like any other method from Mongoose