Python Support

[kothariaditya]

Approach discussed here: #237

Rules supported for now:

• String
• Bool
• Numbers
• Messages
• Wrapper
• Duration
• Timestamp
• Enums
• Any

Rules to be supported in next iteration:

• Maps
• Repeated
• Oneofs
• Bytes

[dkunitsk]

High level feedback: let's transition the string building to a templating engine, maybe Jinja

[dkunitsk]

High level question: is it possible to somehow group the various templates into classes?? So it's clear how they fit together.

[dkunitsk]

Also, one thing that could be helpful. For each tests, could you output a string of the validate function and then post the output here for us.

[rodaine]

Can you confirm for me that this works for 2.x as well as 3.x? Do we have a test covering both versions?

[rodaine]

Please take a look at the exceptions from the other languages and include the other ancillary information that will help developers track down the source of their errors.

[kothariaditya]

Have included the ancillary info while raising the exception. For example here:
https://github.com/envoyproxy/protoc-gen-validate/pull/238/files#diff-2c27ae30e4a405617a8988599f7e85f9R88

raise ValidationFailed(\"{{ name }} not equal to {{ o.string['const'] }}\")

This can then be caught and read as follows:

except ValidationFailed as e:
    reason = str(e)

Please let me know if you think I missed anything here.

[kothariaditya]

Generated code for KitchenSinkMessage would be:

# Validates KitchenSinkMessage
def validate(p):

    if _has_field(p, "val"):
        embedded = generate_validate(p.val)(p.val)
        if embedded is not None:
            return embedded
    return None

# Validates ComplexTestMsg
def validate(p):

    if p.const != "abcd":
        raise ValidationFailed("const not equal to abcd")

    if _has_field(p, "nested"):
        embedded = generate_validate(p.nested)(p.nested)
        if embedded is not None:
            return embedded
    if p.int_const != 5:
        raise ValidationFailed("int_const not equal to 5")

    if p.bool_const != False:
        raise ValidationFailed("bool_const not equal to False")

    if p.HasField("float_val"):
            if p.float_val.value <= 0.0:
                raise ValidationFailed("float_val.value is not greater than 0.0")

    if not _has_field(p, "dur_val"):
        raise ValidationFailed("dur_val is required.")
    if _has_field(p, "dur_val"):
        dur = p.dur_val.seconds + round((10**-9 * p.dur_val.nanos), 9)
        lt = 17.0
        if dur >= lt:
            raise ValidationFailed("dur_val is not lesser than 17.0")

    if _has_field(p, "ts_val"):
        ts = p.ts_val.seconds + round((10**-9 * p.ts_val.nanos), 9)
        gt = 7.0

        if ts <= gt:
            raise ValidationFailed("ts_val is not greater than 7.0")

    if _has_field(p, "another"):
        embedded = generate_validate(p.another)(p.another)
        if embedded is not None:
            return embedded

    if p.float_const >= 8.0:
        raise ValidationFailed("float_const is not lesser than 8.0")

    if p.double_in not in [456.789, 123.0]:
        raise ValidationFailed("double_in not in [456.789, 123.0]")

    if p.enum_const != 2:
        raise ValidationFailed("enum_const not equal to 2")


    if _has_field(p, "any_val"):
        if p.any_val.type_url not in ['type.googleapis.com/google.protobuf.Duration']:
            raise ValidationFailed("any_val not in ['type.googleapis.com/google.protobuf.Duration']")

    return None

[kothariaditya]

@rodaine confirming this works for Python 2.x and 3.x. The version is set by default to PY2AND3 as per https://docs.bazel.build/versions/master/be/python.html.

[rodaine]

This looks great! And I think we can continue to iterate on it to make it better.

[kothariaditya]

Awesome, thanks a bunch!