domain

Documentation

Index

• Constants
• type Link
  • func NewLink(boardId, title, url string, user User) (Link, error)
  • func (l *Link) IsValid() error
• type LinkDataStore
• type LinkQueryParams
  • func NewLinkQueryParams() LinkQueryParams
  • func (l LinkQueryParams) SortByNewest() LinkQueryParams
  • func (l LinkQueryParams) SortByTop() LinkQueryParams
  • func (l LinkQueryParams) WithCreatedTimeCursor(t int64) LinkQueryParams
  • func (l LinkQueryParams) WithLimit(limit int) LinkQueryParams
  • func (l LinkQueryParams) WithScoreCursor(score int) LinkQueryParams
• type LinkReturnFields
• type LinkService
  • func NewLinkService(ds LinkDataStore) *LinkService
  • func (ls *LinkService) CreateLink(ctx context.Context, boardId string, title string, url string, user User) (Link, error)
  • func (ls *LinkService) UpdateUserRating(ctx context.Context, boardId string, linkId string, rating int, user User) (UserLinkRating, error)
• type LinkWithRating
• type Rating
• type SortOrder
• type User
• type UserLinkRating
  • func NewUserLinkRating(rating int, userId string) (UserLinkRating, error)

Constants

const SortOrderNewest = "newest"

const SortOrderTop = "top"

Types

type Link

type Link struct {
	BoardId string
	LinkId  string

	Title string
	Url   string

	CreatedTime int64
	CreatedBy   User
}

func NewLink

func NewLink(boardId, title, url string, user User) (Link, error)

func (*Link) IsValid

func (l *Link) IsValid() error

type LinkDataStore

type LinkDataStore interface {
	CreateLink(ctx context.Context, boardId string, link Link) error
	DeleteLink(ctx context.Context, boardId string, linkId string) error

	UpdateRating(ctx context.Context, boardId string, linkId string, rating UserLinkRating) error

	// Return a single link, possibly with a rating summary and the rating for a particular user, depending on the LinkReturnFields value.
	Link(ctx context.Context, boardId string, linkId string, rf LinkReturnFields) (LinkWithRating, error)
	Links(ctx context.Context, boardId string, rf LinkReturnFields, qp LinkQueryParams) ([]LinkWithRating, error)
}

Any type implementing this interface can be used as the link and rating data store for this application.

Note that we do not aggregate the user ratings in the domain layer. Instead we expect that the data store implementation is capable of computing a Rating value that aggregates all the user ratings. How this is done is up to the implementation. One could e.g. store the aggregate explicitly and update it every time a user rating changes or it could be computed from all the user ratings and cached.

type LinkQueryParams

type LinkQueryParams struct {
	// Should be either newest or top, defaults to newest
	SortOrder SortOrder
	// Maximum number of links to return.
	// Valid values are between 1 and 100, defaults to 20.
	Limit int

	// Query cursors that can be used for pagination.
	// When sort order is "newest", just provide CursorCreatedTime.
	// When sort order is "top", provide both values,
	// since there can possibly be many links with the same score.
	//
	// Return only links with less than or equal to score.
	// Use a pointer here to distinguish the case where no value is set, since 0 would be a valid cursor value.
	CursorScore *int
	// Return only links that were created at or before the given time.
	CursorCreatedTime int64
}

func NewLinkQueryParams

func NewLinkQueryParams() LinkQueryParams

func (LinkQueryParams) SortByNewest

func (l LinkQueryParams) SortByNewest() LinkQueryParams

func (LinkQueryParams) SortByTop

func (l LinkQueryParams) SortByTop() LinkQueryParams

func (LinkQueryParams) WithCreatedTimeCursor

func (l LinkQueryParams) WithCreatedTimeCursor(t int64) LinkQueryParams

func (LinkQueryParams) WithLimit

func (l LinkQueryParams) WithLimit(limit int) LinkQueryParams

func (LinkQueryParams) WithScoreCursor

func (l LinkQueryParams) WithScoreCursor(score int) LinkQueryParams

type LinkReturnFields

type LinkReturnFields struct {
	// Wether or not to include the rating of the link
	IncludeRating bool
	// Whether or not to include the rating of the user with the given userId (if not empty)
	IncludeUserRatingFor string
}

Defines what data a LinkDataStore query result should contain

type LinkService

type LinkService struct {
	// contains filtered or unexported fields
}

func NewLinkService

func NewLinkService(ds LinkDataStore) *LinkService

func (*LinkService) CreateLink

func (ls *LinkService) CreateLink(ctx context.Context, boardId string, title string, url string, user User) (Link, error)

func (*LinkService) UpdateUserRating

func (ls *LinkService) UpdateUserRating(ctx context.Context, boardId string, linkId string, rating int, user User) (UserLinkRating, error)

Creates or changes the rating of a user for a link.

type LinkWithRating

type LinkWithRating struct {
	Link Link
	// Rating of the link, might be empty
	Rating Rating
	// Rating of the link from a user, might be empty
	UserRating UserLinkRating
}

For convenience, LinkDataStore should be able to return a link with its rating (i.e. the summary/aggregate of all user ratings) and possibly the individual rating of a given user. A LinkReturnFields value can be used to configure what a LinkDataStore method should return.

type Rating

type Rating struct {
	// Score = Upvotes + Downvotes
	Score int
	// Total of positive ratings, must be >= 0
	Upvotes int
	// Total of negative ratings, must be <= 0
	Downvotes int
}

A summary/aggregate of all the ratings for a link

type SortOrder

type SortOrder string

type User

type User struct {
	UserId string
	Name   string
}

type UserLinkRating

type UserLinkRating struct {
	UserId string
	// +1 for upvote, -1 for downvote
	Rating       int
	ModifiedTime int64
}

The rating of a user for a link.

func NewUserLinkRating

func NewUserLinkRating(rating int, userId string) (UserLinkRating, error)