Which is kind of the same mathematically speaking. So it might mean matching tables in a database with objects in code. Or performing an operation on each item in a list. A mapper is a function or class which matches items in one set with items in another. –

The Mapper is essentially a constructor inside out. Suppose for a while, if you don't have a Mapper - when you need many seta of parameters they are all arguments on the constructor. Now as things evolve, some applications are not aware of additional attributes that needs to go under constructor where one either computes it or use default.

2021年1月5日 · But here the problem, When mapper starts to convert Engine it will get LazyInitializationException since transaction was already committed and closed in service and Engine is lazy initialized That moves us to Scenario#2 Ok so do the conversions in service then daa! while you still have the transaction opened, in service, so update the getCar ...

2023年6月28日 · The problem there is that that now makes the Repository as dependent on the DB as the Data Mapper, which "feels wrong". The alternative is some other abstraction has to be injected into Repository along with the Data Mapper. Or else, add more logic to Data Mapper, but then we get into eroding the careful distinction between the two.

2022年1月7日 · Am I correct in thinking that when I receive data in the controller I would pass this over to the service, at this point the service should first fetch that data from the repository and then map it into a domain entity.

2015年9月10日 · Therefore, Data Mapper is perfect for representing non-trivial domain model. If your domain model is rather simple you might consider using Active Record pattern or Data Gateways. Need for JOINs Data Mapper might sometimes (but not must) indicate that domain class is too complex.

2013年2月4日 · What would be the "proper" way to handle it. The application I currently work with utilizes separate mapper class for every possible translation, and although it has benefits of testability we are using dependency injection and we have to pass all those mappers as dependencies in the constructor. Has anybody figured out a better way to do it ...

2015年11月3日 · Converter/Mapper class. I create separate class that will handle conversions and implement methods that will take source class instance as an argument and return destination class instance. To sum up, my problem can be reduced to number of questions (all in context to what I described above):

2020年9月29日 · He does not control it. The lib in question is also not slow or so slow that it would need to be mocked for performance, so I don't think it should be mocked. It could be replaced with a custom mapper later. When testing the OP's methods I don't think that the call to the mapper matters, what I care about is that the result of the method is ...

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