Pyrseas was started to improve on Andromeda. In addition to the schema version control I’ve been discussing in these posts, Andromeda provides two other capabilities: automations and web application programming.
Andromeda’s web programming allows you to generate a database application with very little actual programming, since Andromeda takes into account the primary key, foreign key and other information present in the YAML specification to generate much of the application code for you. This is another area that I’d like to explore for implementation in Pyrseas.
Nearly any database needs a user interface to add, retrieve, update and delete records, known by the unattractive acronym CRUD. There are a number of admin apps that provide such generic facilties. For example, for PostgreSQL we have pgAdmin which offers a GUI, and phpPgAdmin and Adminer which offer PHP web interfaces. These have a couple of limitations.
Admin apps almost always operate on a single table at a time. Interfaces for end users often require interacting with or viewing two or more tables on a single screen or page, e.g., customers with their invoices, accounts with their transactions.
By definition, admin apps are “raw” and cater to the needs of DBAs and programmers. After retrieving a customer record searching by name, the admin user can update any column, including the primary key and other columns that end users would normally be prevented from updating.
Django includes an appealing admin site. With a moderate dose of programming, you can develop an application suitable for end users. However, you’re at the mercy of Django’s constraints on “modeling” a database. Take for example the film_category table I used in my second post on version control:
CREATE TABLE film_category ( film_id INTEGER NOT NULL REFERENCES film (id), category_id INTEGER NOT NULL REFERENCES category (category_id), last_update TIMESTAMP WITH TIME ZONE NOT NULL, PRIMARY KEY (film_id, category_id) );
Django cannot use this table “as is” because it insists in having a single column as the primary key. So you end up adding an unnecessary “id” column together with a SEQUENCE (and needless to say, you incur the wrath of the SSSKA).
We could turn to SQLAlchemy, a Python-based ORM that understands that a primary key –albeit singular– can encompass more than one column, and some other web framework or even Django itself, and attempt to recreate the nice Django admin app. However, aside from the additional effort that would represent, we wouldn’t be taking advantage of the YAML database specification we can now store in our VCS.
This is a very broad, and some may say, ambitious topic, but as I did with version control, in future posts I’ll survey existing “art” and progress towards designing and implementing a generic end user interface for PostgreSQL. Reader feedback will be much appreciated.