Refactor DAO methods

[hacksparrow]

Currently, DAO methods don't have a uniform way of processing and generating the result model. Ideally, the model object should be generated by a single pipeline, which would be invoked by all the DAO methods that deal with data retrieval.

Take a look at the differences in how the model data is created in the callback function of these DAO methods:

create: https://github.com/strongloop/loopback-datasource-juggler/blob/261dd1c865e8b197882a161b909b90b0e6c3c2a3/lib/dao.js#L383
save: https://github.com/strongloop/loopback-datasource-juggler/blob/261dd1c865e8b197882a161b909b90b0e6c3c2a3/lib/dao.js#L2137
replaceById: https://github.com/strongloop/loopback-datasource-juggler/blob/261dd1c865e8b197882a161b909b90b0e6c3c2a3/lib/dao.js#L2700
find: https://github.com/strongloop/loopback-datasource-juggler/blob/261dd1c865e8b197882a161b909b90b0e6c3c2a3/lib/dao.js#L1622

If DAO methods do their own thing, implementing new features or bug fixes that center around the model object will require changes for each DAO method.

[dhmlau]

With the juggler-next work in mind, would it make more sense to ensure the consistency there?

cc @bajtos @raymondfeng

[bajtos]

Yeah, I agree this is probably best to defer to juggler-refactor Epic.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

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This issue has been closed due to continued inactivity. Thank you for your understanding. If you believe this to be in error, please contact one of the code owners, listed in the CODEOWNERS file at the top-level of this repository.