Log.emiter does not work with a Union type

[erdnaxeli]

Hi,

With this code

require "log"

a = 2
if a % 2 == 0
  a = 0_u8
end

pp typeof(a)  # => (Int32 | UInt8)
Log.info &.emit("test", a: a)

I got the following error:

Showing last frame. Use --error-trace for full trace.

In /usr/share/crystal/src/log/metadata.cr:217:42

 217 | value.is_a?(Value) ? value : Value.new(value)
                                          ^--
Error: no overload matches 'Log::Metadata::Value.new' with type (Int32 | UInt8)

Overloads are:
 - Log::Metadata::Value.new(raw : Type)
 - Log::Metadata::Value.new(hash : NamedTuple | Hash)
 - Log::Metadata::Value.new(ary : Array)
Couldn't find overloads for these types:
 - Log::Metadata::Value.new(UInt8)

I see by diging in the doc that it exists Log::Metadata::Value::Type that define all supported types but:

• this is never stated in the emit doc
• I expect it to work with any type, by defaulting to print the same output as p!

[straight-shoota]

This is not caused by a union type, but UInt8 is not supported:

Log.info &.emit("test", a: 0_u8) # Error: no overload matches 'Log::Metadata::Value.new' with type UInt8

The log metadata is represented as a relatively simple data structure which supports only a hand full of primitive data types for values. You'll have to convert the number to Int32 to pass it as log metadata. Or use some other form of serialization.

[bcardiff]

The supported types are the ones listed in https://crystal-lang.org/api/1.0.0/Log/Metadata/Value/Type.html . The actionable here is to improve the docs of emit. It is not expected for the Log::Metadata to handle arbitrary types.

[erdnaxeli]

Well, neither Union nor UInt8 feels like arbitrary types to me :p. Maybe we should add for all primitive types (U)Int?

[straight-shoota]

It is very arbitrary. For logging purposes, there's not much reason to preserve specific integer types. Just convert it to Int32.