Here we ensure that the key student_id is part of the request. Although this validation works, it really does not belong in the function itself. Plus, perhaps there are other routes that use the exact same validation. So, let’s keep it DRY and abstract out any unnecessary logic with a decorator. The following @validate_json decorator will do the job:
In a previous article, we discussed how to use the strategy pattern to dynamically change an object’s behavior at runtime. Classically, polymorphism in object-oriented design is static and achieved through inheritance; however, with the strategy pattern you can accomplish the same goal dynamically. Indeed, this is an excellent way to handle situations when you need an object to exhibit different behavior at different times. However, it’s worth noting that the strategy pattern requires mutation of the object you’re working with. By using the strategy pattern, you are necessarily changing the algorithm that an object uses for a given behavior. In some situations, it may be preferable not to mutate a given object. Or more likely, you won’t even have the option of mutating an object because it may come from a codebase over which you have no control (such as an external library). Such cases are relatively common; however, it’s still possible to enhance an immutable object’s behavior. One effective means to do so is with the decorator pattern.

Painters work both indoors and out. Outside work is done in relatively mild weather. In some jobs, especially maintenance and redecoration of offices and buildings, the painter may be required to work evenings or weekends. Work is seasonal; however, new materials and methods tend to give more steady employment throughout the year. Physical and health hazards include the dangers of poisoning, falling from ladders and scaffolds, breathing paint fumes and dust. The work involves standing, bending, climbing and working with arms over the head much of the time.
None of these alternatives gained much traction. The alternatives which involve square brackets only serve to make it obvious that the decorator construct is not a list. They do nothing to make parsing any easier. The '<...>' alternative presents parsing problems because '<' and '>' already parse as un-paired. They present a further parsing ambiguity because a right angle bracket might be a greater than symbol instead of a closer for the decorators.
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