Catalog Delta

A CatalogDelta represents an incremental update to an existing catalog. Instead of resending the full track list, a delta contains add, remove, and clone operations.

Parse and Apply

    delta, err := msf.ParseCatalogDelta(deltaJSON)
    if err != nil {
        // handle error
    }

    updated, err := baseCatalog.ApplyDelta(delta)
    if err != nil {
        // handle error
    }

`msf.CatalogDelta`

type CatalogDelta struct {
    DefaultNamespace string
    GeneratedAt      *int64
    IsComplete       bool
    AddTracks        []Track
    RemoveTracks     []TrackRef
    CloneTracks      []TrackClone
}

func ParseCatalogDelta(data []byte) (CatalogDelta, error)
func ParseCatalogDeltaString(s string) (CatalogDelta, error)
func (d CatalogDelta) Validate() error
func (d CatalogDelta) Clone() CatalogDelta

Delta Operations

Field	Type	Description
`AddTracks`	`[]Track`	New tracks to append to the catalog
`RemoveTracks`	`[]TrackRef`	Tracks to remove (by namespace + name)
`CloneTracks`	`[]TrackClone`	New tracks derived from an existing parent track

The operation order declared in the original JSON is preserved during application.

`TrackRef`

Identifies a track by namespace and name, used in RemoveTracks:

type TrackRef struct {
    Namespace string
    Name      string
}

`TrackClone`

Describes a clone operation — a new track derived from an existing parent with optional overrides:

type TrackClone struct {
    Track               // override values
    ParentName string   // source track to clone from
}

Example

    base, _ := msf.ParseCatalog(baseJSON)

    delta, _ := msf.ParseCatalogDelta([]byte(`{
        "deltaUpdate": true,
        "addTracks": [
            {"namespace": "ns", "name": "subtitle", "packaging": "loc"}
        ],
        "removeTracks": [
            {"namespace": "ns", "name": "old-audio"}
        ]
    }`))

    updated, err := base.ApplyDelta(delta)
    if err != nil {
        // handle error
    }

Catalog Timeline