Re: How to use the encoder for `values()` so to behave as if it's still using DRF encoder?

[Jason]

Nice work!

I think this was an explicit decision by Tom back in 2014.  Using 
https://github.com/encode/django-rest-framework/commit/040bfcc09c851bb3dadd60558c78a1f7937e9fbd
 for 
reference, you can see DecimalField 

 was 
re-written to use string coercion, though it wasn't a setting at the time.  
In the same commit, JSONEncoder changed the output of a Decimal from str to 
floa 

t

I'm not sure having the JSONEncoder know about COERCE_TO_STRING is a good 
thing.  It is True by default, which could cause some major unexpected 
behavior in JSONEncoder by taking that into consideration.  I think your 
approach of making a custom encoder for your project is the best direction.

I do have some comments about your encoder.

https://github.com/encode/django-rest-framework/blob/335054a5d36b352a58286b303b608b6bf48152f8/rest_framework/utils/encoders.py
  
is the DRF implementation.  It seems you basically duplicate the datetime 
encoding, so it seems to me you could just use the decimal conditional 
check.

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How to use the encoder for `values()` so to behave as if it's still using DRF encoder?

[TJ Simmons]

I am using DRF and i have a situation where I have too many database calls.

So I used `values()` for one of the serializers to reduce the number of 
calls.

I tweeted about it as well 
https://twitter.com/KimStacks/status/1190942972273025024

I am of course not sure if this is the best way to solve it. In Tom 
Christie's piece he mentioned about using values here 
https://www.dabapps.com/blog/api-performance-profiling-django-rest-framework/

I quote

>4. You don't always need to use serializers.
>
>For performance critical views you might consider dropping the serializers 
entirely and simply use .values() in your database queries. If you're using 
hyperlinked representations or other complex fields you might find you also 
need to do some post processing on the data structures before returning 
them in the response. REST framework is designed to make this easy.

Ok so far so good. One API i have issues with went from 800+ database 
queries to 16. I consider that a success.

Then, when I run my unit tests, things fail.

Why? Because the datetime format expected was wrong. So I used DRF's own 
JSOEncoder which fixed this issue but broke another thing.

I also have decimal values which usually converts to STRING because of the 
default COERCE_DECIMAL_TO_STRING setting. See 
https://github.com/encode/django-rest-framework/blob/b26db128135fcd10c890213d8d56af8cf0a171a0/docs/api-guide/settings.md#coerce_decimal_to_string

Now unfortunately this setting applies the coercion at the serializer 
level. Not the encoder level.

SO if i use `JSONEncoder().default(this_is_a_decimal)` i will get back 
float. Not string. So I had to write my own encoder.

https://gist.github.com/simkimsia/ab96a26bcb3a735fa416c33d75e576db

My question is is this something that can be improved within the DRF 
library? if so, I will be happy to send a PR.

I wasn't sure and I didn't want to pollute the github issues hence i posted 
here for advice.

Thank you

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