apollo-graphql服务器中的分页

Question

我想在Apollo graphql服务器中实现基于游标的分页。我已准备好具有分页要求的架构。但是我被困在解析器方面。这是我的架构

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];

是否可以在解析器中解决？如果是，请告诉我如何实施]

Answer 1

如果您将Mongo和Mongoose与Apollo Express GraphQL一起使用，我发现了三种进行分页的方法：

1. 您可以在架构上创建cursor字段并使用分页逻辑实现解析器，但是如果您有一个复杂的架构，该架构包含联合，接口和不同类型的嵌套对象，则不建议使用此方法，但是如果您想自己实现它，请点击reference

2. 您可以使用module来嵌套您的Mongoose模型并为您提供分页界面，但这需要对架构和解析器进行一些更改，然后是第三种方法的更多工作

3. 您可以使用Mongo / Mongoose中的sort，skip和limit，但是如果您自己执行此操作，则可以找到一些issues，例如，如果文档是按日期键排序的，具有相同日期的不同文档，它可以复制文档并弄乱您的分页，因此我建议您在Mongoose模式上安装一个分页插件，并像Mongoose的任何其他方法一样使用它。