Data modeling


clld.db.models.common.Parameter objects are used to model language parameters, i.e. phenomena (aka features) which can be measured across languages. Single datapoints, i.e. measurements of the parameter for a single language are modeled as instances of clld.db.models.common.Value. To support multiple measurements for the same (language, parameter) pair, values are grouped in a clld.db.models.common.ValueSet, and it is the valueset that is related to language and parameter.

Enumerated domain

clld supports enumerated domains. Elements of the domain of a parameter can be modeled as clld.db.models.common.DomainElement instances and each value must then be related to one domain element.

The clld framework will then use the domain property of a parameter to select behaviour suitable for enumerated domains only, e.g. loading values associated with one domain element as separate layer when displaying a parameter map.

Typed values

The clld framework is agnostic with regard to the types of values, i.e. as far as default functionality is concerned the only properties required of a value are a name and an id (and optionally a description). To simply store typed data for values multiple mechanisms are available.

  • Storing typed data in the jsondata dictionary: This accomodates all data types which can be serialized as JSON, i.e. numbers, booleans, arrays, dictionaries.
  • If the data for a value comes as a list or dictionary of strings, it can also be stored as clld.db.models.common.Value_data instances.
  • Finally there’s the option to store data related to a value as files, i.e. as instances of clld.db.models.common.Value_files.