[go]: Range Checks and Null Values?

[meyerdan]

We are generating Encoders/Decoders for go.

In our schema, we have a field, defined as follows:

<field name="position" id="2" type="uint64" presence="optional" />

Our question goes to the range-checking which can be enabled in the generated decoder.
We observe that the check is generated as follows, regardless whether the presence="optional" attribute is set or not:

  if s.PositionInActingVersion(actingVersion) {
        if s.Position < s.PositionMinValue() || s.Position > s.PositionMaxValue() {
            return fmt.Errorf("Range check failed on s.Position (%d < %d > %d)", s.PositionMinValue(), s.Position, s.PositionMaxValue())
        }
    }

If a null value is received, it will be s.PositionMaxValue() + 1.

Our question is: should the range check code accommodate for null values or are we maybe confusing something?

[billsegall]

I think it's a bug. I'll have a look.

[billsegall]

I'm seeing token.presence() is always REQUIRED (which is why is token.isOptionalEncoding() is returning false on me. My test file is quite simple:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<sbe:messageSchema xmlns:sbe="http://fixprotocol.io/2016/sbe"
                   package="issue472"
                   id="472"
                   version="0"
                   semanticVersion="1.0"
                   description="issue 472 test case"
                   byteOrder="bigEndian">
    <types>
        <composite name="messageHeader" description="Message identifiers and length of message root">
            <type name="blockLength" primitiveType="uint16"/>
            <type name="templateId" primitiveType="uint16"/>
            <type name="schemaId" primitiveType="uint16"/>
            <type name="version" primitiveType="uint16"/>
        </composite>
    </types>
    <sbe:message name="issue472" id="1" description="issue 472 test">
        <field name="position" type="uint64" id="2" presence="optional"/>
    </sbe:message>
</sbe:messageSchema>

[mjpt777]

The optional is applied to the field here and not the type. The IR has this reflected in the field token vs the contained type token(s). The spec has some issues here. For example, presence is available on basic types but not composites, enums, or bitsets. There are also issues with minValue, maxValue, and nullValue being available on the type but not the field. I personally believe the type should not have presence or restrictions and they should only be on the field. Maybe @donmendelson has a view here?

[donmendelson]

See issue FIXTradingCommunity/fix-simple-binary-encoding#31
This change has already been approved by working group. I'd appreciate review of the proposed change for SBE version 2.0 RC1.

[billsegall]

See #475