IMPR: Documentation for populate generator

[CBroz1]

Improvement Request

Problem

#1204 added the ability to delay the transaction within a populate call until needed, but did not provide instructions/documentation on proper use of this feature.

Does it require two yields? Before and after the inserts, but what should I yield to preserve referential integrity?

class MyTable(dj.Computed):
    ...
    def make(self, key):
        ret = some_processing(key)
        yield key # ?
        self.insert1(ret)
        yield key # ?

In an initial implementation attempt, I saw a StopIteration error with only one yield.

Requirements

A description of how to implement/benefit from this feature

Related Errors

Please include steps to reproduce provided errors as follows:

• OS Linux
• Python Version: 3.9.18
• MySQL Version: 8.0.34
• MySQL Deployment Strategy: local-docker
• DataJoint Version: 0.14.4
• Minimum number of steps to reliably reproduce the issue: n/a
• Complete error stack as a result of evaluating the above steps: n/a

Screenshots

n/a

[dimitri-yatsenko]

This was improved in #1241.

[CBroz1]

Ah, ok. Thanks, @dimitri-yatsenko. I was under the impression that this feature was available in 0.14.4, but I'm hitting the bug that #1241 fixed in my CICD. It looks like I'll have to wait for the next release to put this in practice

Appropriate syntax for anyone on pre-release...

@schema
class MyTable(dj.Computed): 
    ...

    class MyPart(dj.Part): 
        ...

   def make_fetch(self, key):
        some_data = Upstream().fetch_relevant(key)
        return [some_data] # I hit an error if a single item was not passed as a list

    def make_compute(self, key, some_data):
        some_insert_1 = self.computation1(some_data)
        some_insert_2 = self.computation2(some_data)
        return some_insert_1, some_insert_2

    def make_insert(self, key, some_insert_1, some_insert_2):
        self.insert1(some_insert_1)
        self.MyPart.insert1(some_insert_2)

[dimitri-yatsenko]

Yes, @CBroz1, and thank you. I missed one merge before making release 0.14.4, so only the generative version made it into the release. We are preparing a new release, including the documentation shortly. 0.14.5