Database Models
Entity-Relationship Diagram for Wazimap-NG The Django apps and database models are divided into roughly two groups: models that store data, and models that are used to present information to the end-user.
Entity Relationship Diagram for the Datasets App Dataset and DatasetData
Data models can be found in the datasets app. The central model is Dataset. It represents a dataset that was uploaded by the . Each dataset is associated with a . Data files uploaded to the system are expected to have the following structure:
Only the Geography, Count, and at least one additional column are required. An example table might look as follows:
When this file is uploaded, a new Dataset object is created. Each row is stored in a DatasetData object. A typical DatasetData object might look as follows:
All groups and the Count column are stored in a JSONField.
Indicators and IndicatorData
Another key concept is an Indicator. Indicators represent saved aggregations and filters on a dataset. For example, the above Dataset can be used to create an Indicator containing population per geography disaggregated by gender. The equivalent query in SQL would look something like this:
Similarly, another indicator can be created to return population disaggregated by age.
When a new indicator is created, data from DatasetData is processed to create an IndicatorData object, one per geography. A simplified version of and IndicatorData would like something like this:
The actual structure of IndicatorData objects is a little more complicated. More detail can be found here: .
Universes represent saved filters on queries and enable the Data Administrator to run a query on a subset of the database. The default Universe is the total of all the distinct observations in a geography (e.g. the total population of the geography). It is possible to create a custom Universe and apply it to an Indicator.
A Universe which creates a filter on gender can enable queries on Female exclusively. PseudoSQL to represent this operation
The Universe filters field contains a dictionary that will be used in a Django ORM filter method. Below is an example filter to extract adults 60 and older.
This filter is then passed to the Django ORM as follows:
Other noteworthy models are Geography and GeographyHierarchy. These are discussed in more detail here: .
Whereas models in the Datasets app focus on data, Profile App models are for presentation to end-users. The key model is Profile. A profile is a view of the data curated by the . Each profile can be considered to be a complete Wazimap instance. A profile organises tabular data in Categories (IndicatorCategory) and Subcategories (IndicatorSubcategory). This data can be presented using three different models:
ProfileIndicator, ProfileKeyMetrics, and ProfileHighlight. ProfileIndicator is the most commonly used of the three.
ProfileIndicators present Indicators. They provide explanatory text, a custom label, and other attributes that control presentation. They are used in the Rich Data Panel in the form of graphs and the Data Mapper Panel in the form of .
ProfileKeyMetrics display only a single value from an Indicator. For instance, the number of youth between 15-24 living in the area.
ProfileHighlights are similar to ProfileKeyMetrics in that they display a single value from an Indicator, but are displayed in the Map View rather than the Rich Data View.
