Question

Accordingly to protocol buffer python generated code documentation,
I can add a object to a repeated message field this way:

foo = Foo()
bar = foo.bars.add()        # Adds a Bar then modify
bar.i = 15
foo.bars.add().i = 32       # Adds and modify at the same time

but:

1. how can I remove bar from bars?

2. how can I remove the n-th bar element from bars?

Answer 1

It took me more than a few minutes to get the proto buffer compiler installed correctly, so that may be reason enough to ignore this 🙂

Although it isn’t in the documentation, you can actually treat a repeated field much like a normal list. Aside from its private methods, it supports add, extend, remove and sort, and remove is what you are looking for in the first case:

foo.bars.remove(bar)

Here is the output when printing foo before the above line (as defined by your code above) and after:

Original foo:
bars {
  i: 15
}
bars {
  i: 32
}

foo without bar:
bars {
  i: 32
}

As for removing the nth element, you can use del and the index position you want to delete:

# Delete the second element
del foo.bars[1]

And the output:

Original foo:
bars {
  i: 15
}
bars {
  i: 32
}

Removing index position 1:
bars {
  i: 15
}

Hope that helps!