WIP: Create an abstraction layer for the database

[christianlupus]

To allow for simpler development and future implemntation, this PR provides an internal API to the database.

It is related to #301.

Currently this PR is under development and should be considered Work in Progress. Suggestions and enhancements are welcome.

• creating valid architecture
• implemented features
• test code
• document interface
• write unit test files

[codecov]

Codecov Report

Merging #407 (8e731e3) into master (f717e11) will decrease coverage by 0.24%.
The diff coverage is 0.00%.

@@             Coverage Diff             @@
##             master    #407      +/-   ##
===========================================
- Coverage      0.87%   0.62%   -0.25%     
- Complexity      436     600     +164     
===========================================
  Files            14      30      +16     
  Lines          1375    1914     +539     
===========================================
  Hits             12      12              
- Misses         1363    1902     +539     

Flag	Coverage Δ	Complexity Δ
integration	0.00% <0.00%> (ø)	0.00 <199.00> (ø)
unittests	0.62% <0.00%> (-0.25%)	0.00 <199.00> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ	Complexity Δ
lib/Db/AbstractDbWrapper.php	0.00% <0.00%> (ø)	8.00 <8.00> (?)
lib/Db/CategoryDbWrapper.php	0.00% <0.00%> (ø)	8.00 <8.00> (?)
lib/Db/CategoryMappingDbWrapper.php	0.00% <0.00%> (ø)	11.00 <11.00> (?)
lib/Db/DbWrapperServiceLocator.php	0.00% <0.00%> (ø)	6.00 <6.00> (?)
lib/Db/KeywordDbWrapper.php	0.00% <0.00%> (ø)	8.00 <8.00> (?)
lib/Db/KeywordMappingDbWrapper.php	0.00% <0.00%> (ø)	11.00 <11.00> (?)
lib/Db/RecipeDbWrapper.php	0.00% <0.00%> (ø)	31.00 <31.00> (?)
lib/Entity/RecipeJSONEntity.php	0.00% <0.00%> (ø)	26.00 <26.00> (?)
lib/Entity/impl/AbstractEntity.php	0.00% <0.00%> (ø)	7.00 <7.00> (?)
lib/Entity/impl/CategoryEntityImpl.php	0.00% <0.00%> (ø)	11.00 <11.00> (?)
... and 31 more

[seyfeb]

What about creating categories as actual objects that can have, e.g., a description or other metadata? 😇

[christianlupus]

Simply put: No. 😁

The current DB schema has only a category name stored in a mapping type table. I kept with that for now. See also #300.

I was planning to proceed as follows:

1. Create the entities and a DB abstraction layer parallel to the current main work.
2. Deprecate major parts of the current RecipeDbService and refactor the DbCacheService that use direct DB operations.
3. Migrate and refactor any current usage of any of these methods in the codebase
4. Migrate any pending PRs to the new system
5. Remove the direct DB access

After the DB access has been encapsulated as described here, we can add further setter/getter and fields in the DB without affecting the functionality of other parts.