In this chapter, we will discuss the following topics:
- Reading a Django code base
- Discovering relevant documentation
- Incremental changes versus full rewrites
- Writing tests before changing code
- Legacy database integration
It sounds exciting when you are asked to join a project. Powerful new tools and cutting-edge technologies might await you. However, quite often, you are asked to work with an existing, possibly ancient, code base.
To be fair, Django has not been around for that long. However, projects written for older versions of Django are sufficiently different to cause concern. Sometimes, having the entire source code and documentation might not be enough.
If you are asked to recreate the environment, you might need to fumble with the OS configuration, database settings, and running services locally or on the network. There are so many pieces to this puzzle that you might wonder how and where to start.
Understanding the Django version used in the code is a key piece of information. As Django evolved, everything from the default project structure to the recommended best practices have changed. Therefore, identifying which Version of Django was used is a vital piece in understanding it.
Sitting patiently on the ridiculously short beanbags in the training room, the SuperBook team waited for Hart. He had convened an emergency go-live meeting. Nobody understood the emergency part since go-live was at least three months away.
Madam O rushed in holding a large designer coffee mug in one hand and a bunch of printouts of what looked like project timelines in the other. Without looking up she said, "We are late, so I will get straight to the point. In the light of last week's attacks, the board has decided to summarily expedite the SuperBook project and has set the deadline to the end of next month. Any questions?"
"Yeah," said Brad, "Where is Hart?" Madam O hesitated and replied, "Well, he resigned. Being the head of IT security, he took moral responsibility for the perimeter breach." Steve, evidently shocked, was shaking his head. "I am sorry," she continued, "But I have been assigned to head SuperBook and ensure that we have no roadblocks to meet the new deadline."
There was a collective groan. Undeterred, Madam O took one of the sheets and began, "It says here that the remote archive module is the most high-priority item in the incomplete status. I believe Evan is working on this."
"That's correct," said Evan from the far end of the room. "Nearly there," he smiled at others, as they shifted focus to him. Madam O peered above the rim of her glasses and smiled almost too politely.
"Considering that we already have an extremely well-tested and working archiver in our Sentinel code base, I would recommend that you leverage that instead of creating another redundant system."
"But," Steve interrupted, "it is hardly redundant. We can improve over a legacy archiver, can't we? If it isn't broken, then don't fix it", replied Madam O tersely. He said, "He is working on it," said Brad almost shouting, "What about all that work he has already finished?"
"Evan, how much of the work have you completed so far?" asked O, rather impatiently. "About 12 percent," he replied looking defensive. Everyone looked at him incredulously. "What? That was the hardest 12 percent" he added.
O continued the rest of the meeting in the same pattern. Everybody's work was re-prioritized and shoe-horned to fit the new deadline. As she picked up her papers, ready to leave, she paused and removed her glasses. "I know what all of you are thinking... literally, but you need to know that we had no choice about the deadline. All I can tell you now is that the world is counting on you to meet that date, somehow or other." Putting her glasses back on, she left the room.
"I am definitely going to bring my tinfoil hat," said Evan loudly to himself.