Hands-On Software Engineering with Golang

Defining a Go interface for the link graph

To satisfy the list of operations from the previous section, we shall define the Graph interface as follows:

type Graph interface {
    UpsertLink(link *Link) error
    FindLink(id uuid.UUID) (*Link, error)

    UpsertEdge(edge *Edge) error
    RemoveStaleEdges(fromID uuid.UUID, updatedBefore time.Time) error

    Links(fromID, toID uuid.UUID, retrievedBefore time.Time) (LinkIterator, error)
    Edges(fromID, toID uuid.UUID, updatedBefore time.Time) (EdgeIterator, error)
}

The first two methods allow us to upsert a Link model and retrieve it from the backing store if we are aware of its ID. In the following code, you can see the definition of the Link type, whose fields match the ones from the ER diagram:

type Link struct ...