Toaster database
Toaster Uses Django and it's [https://en.wikipedia.org/wiki/Object-relational_mapping ORM for database interaction.
The database table/model definitions can be found in the orm/models.py file. We also have additional models defined for the build controller, these generally the 'behind the scene' way to translate toaster information into the build controller process.
Categories of data in Toaster
Build data
Build data is Layers, Layer_Versions, Recipes, Machines, Packages, Dependencies and all other objects that are output by running a build of a recipe. Once it is created it is never edited or updated. Unless deleted by the user.
Configuration data
Configuration data is data which is provided by Toaster to configure an openembedded based project in Toaster, like Build data this is stored as Layers, Layer_Versions, Recipes and Machines etc. The configuration data can be produced by fetching it from the Layer Index (the toaster start up script attempts to do this for you at first run) from importing information from the toasterconf.json file, importing Layer definitions into Projects via the Import layer page and also from running a build.
Project data
Some data is designated project specific, such as user imported Layer, CustomImageRecipe, Project variables and Builds.
Top level models
There are many intermediate tables in Toaster's database, see diagram. Below are the most top level models on which everything else depends.
Layer and Layer_Version
A Layer_Version is the model in which most other models relate to in Toaster. Every Layer_Version object belongs to a Layer object which contains the common metadata for each 'version' or revision of the Layer.
An example would be that we have a Layer called 'meta-openembedded' which has 3 Layer_Versions; one Layer_Version which is set to the release 'dizzy' one on 'fido' and one on 'master' (in most cases these correspond to git branch names)
Layer 1 - N Layer_Version 1 - N Recipe 1 - N Packages
Recipe
Recipes contain the information about a collection or particular piece of software. This can be the name, version and description and any distribution packages are created by the Recipe.
An example would be a recipe called myrecipe version 1.2 which produces 3 packages myrecipe-dev, myrecipe-dbg and myrecipe
Recipe N - 1 Layer_Version
Recipe 1 - N Package
CustomImageRecipe
This is a special kind of Recipe which has two additional fields; base_recipe and project. base_recipe is the Recipe in which the Custom recipe has been based on and will translate to the 'required' recipe to inherit recipe metadata from and project because this custom recipe belongs to a certain project that has been created.
Package
A Package is the representation of distribution packages produced by a Recipe when it has been built. Package data is almost always Build data since we don't know about packages until they have been produced. The exception is when the package data is used as configuration data to Customise a recipe by adding and removing known packages.
Package N - Recipe 1
Target
When you build a recipe a Target object is created which contains one or more Recipe names, Build object for the build data to go into and the Task that you're asking bitbake to do (default is build the recipe).
