In which the purpose of this app is explained, alongside pointers as to how to use it to add metadata to arbitrary models.
This package provides metadata services that can be attached to existing models to add key-value metadata. It is used in the URY LASS project to store show names, descriptions, thumbnails and other such data.
The django-lass-metadata system defines metadata as a key-value map whereby the same keys can be mapped to different values in different models. The keys are typically referred to by a string, but are themselves contained in a global model alongside some additional properties each key has.
Each collection of metadata attached to a model is known as a metadata strand, and is homogeneous (that is, every value inside it is of the same type).
Each strand is its own model, but the package provides convenience functions for spawning new models for This package provides both a generic metadata abstract model that can be used to define these homogeneous strand models, as well as predefined versions for textual and image-based metadata.
As mentioned before, there is only one key repository shared by all models; this was a design decision primarily for simplicity, but has the result of promoting a common language or taxonomy for all objects inside a domain.
Each key can decide whether or not multiple instances of itself in a strand are allowed, via the metadata.models.MetadataKey.allow_multiple field.
When retrieving a multiple-use metadatum, all values active during the reference date are returned in a list (and the empty list is used to represent no active data); otherwise the latest value is returned (and a KeyError is raised if none are active).
This distinction allows the metadata system to store items such as titles and descriptions unambiguously whilst also being usable for storing, for example, arbitrary tags or notes.
Metadata has an effective range, which means that it can be set to come into and go out of force at given date-times. This allows the metadata system to track history of metadata, instead of just holding the current state.
Metadata also tracks who created it, and (optionally) who approved it for usage.