Support embeddable structs

[dranikpg]

Hi! I've added support for embedded structs as discussed in this issue.

Both pointers and plain fields are supported.

type Person struct {
	ID   int
	Name string
}

type Employee struct {
	Person
	Salary int
}

By default embedded field names are added without prefixes. Name prefixes can be set like for other fields:

type Employee struct {
	Person   `db:"person_"`
	Salary int
}

If two fields have the same name, REL panics during construction:

What I've changed

• documentData indices now store full field paths as []int
• documentDatas are merged for embedded fields during creation
• Embedded pointers are initialized during document creation

Tests

I've added tests for all main cases

[Fs02]

Thank you, this looking great 👍

A few things to improve, can you add:

• Test case for getting value/primary key/primary field from embedded struct
• Test case for setting value to embedded struct
• How to handle embedded struct with duplicate fields

[codecov]

Codecov Report

Merging #262 (415ef5d) into master (1bbbcfd) will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #262   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           47        47           
  Lines         3092      3135   +43     
=========================================
+ Hits          3092      3135   +43     

Impacted Files	Coverage Δ
association.go	100.00% <100.00%> (ø)
collection.go	100.00% <100.00%> (ø)
document.go	100.00% <100.00%> (ø)
util.go	100.00% <100.00%> (ø)

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[dranikpg]

I've added support for name prefixes and updated the description.

How to handle embedded struct with duplicate fields

This is now checked. I've also added some more tests.

---

document.go is now three lines over 500 and codeclimate is complaining. I'd suggest moving pure reflect helper functions, like this to utils.

[Fs02]

document.go is now three lines over 500 and codeclimate is complaining. I'd suggest moving pure reflect helper functions, like this to utils.

Agreed 👍

[dranikpg]

I've moved embedded pointer initialization to document creation. This is a more "eager" approach, but traversing reflect Values and checking nils for field reads is somewhat costly

[Fs02]

I've moved embedded pointer initialization to document creation

hmm, not sure about the correctness of this behavior.
for example if we query/preload a record, and it's not found, then we shouldn't modify the struct

[dranikpg]

I've moved embedded pointer initialization to document creation

hmm, not sure about the correctness of this behavior. for example if we query/preload a record, and it's not found, then we shouldn't modify the struct

So all field reads/writes should be wrapped with pointer checks? Not a problem, I just thought it's somewhat costly.
I guess reads should init pointers, or else functions like PrimaryValue() could fail to return a value 😶

We could Value() make only check for pointers without intializing them. But this would be inconvenient as there is no other way to initialize it other than setting one of its nested values

[Fs02]

Not a problem, I just thought it's somewhat costly

yes right, but it's for the correctness, unless there's better way to implement it 🤔

[Fs02]

So all field reads/writes should be wrapped with pointer checks? Not a problem, I just thought it's somewhat costly.
I guess reads should init pointers, or else functions like PrimaryValue() could fail to return a value 😶

after giving it some thought and re-reading existing implementation, I think reads shouldn't initialize pointer
it should just returns nil if the embedded struct in path is nil

[Fs02]

Thank you!!
just some more small comments, but overall already looking good 🎉

[Fs02]

Thanks for your contribution ❤️
if you have time, maybe you can also help updating the documentation?
https://github.com/go-rel/doc

[dranikpg]

No problem, I'll have a look at it soon