Nullable variables field in request payload

[elenigen]

It looks like the specification is not clear if the client provides a request without variables, does the field "variables" should be assigned "null" or "{}" or both are valid?

Context:
In the altair tool, the default value is set to "{}" (without the double quotes) and in the graphql-java implementation, it's expecting a "null" value if not variables are needed. The result is, the queries are rejected on the server side, so does the server side is too stick or is it the client side which is providing the wrong value?

[IvanGoncharov]

AFAIK, the spec doesn't prevent null or {} and there is only one relevant place on how variables are handled:
http://facebook.github.io/graphql/June2018/#CoerceVariableValues()

So de jure even { foo: "bar" } is valid.

[elenigen]

What do you mean be

So de jure even

... but thanks, I think you answered my question:
Let coercedValues be an empty unordered Map.
I guess by empty, they mean {}, but I'm not understanding why they mention empty unordered Map, since it's empty there's nothing to sort?!

[IvanGoncharov]

TL;DR; Current spec version doesn't enforce any particular format for variableValues

What do you mean be

@elenigen I mean that nothing in the current version of GraphQL Specification prevent any value.

Let coercedValues be an empty unordered Map.
I guess by empty, they mean {}, but I'm not understanding why they mention empty unordered Map, since it's empty there's nothing to sort?!

coercedValues is the result of coercion and variableValues is what you supply to GraphQL.
variableValues is used only in 3e & 3f and they executed only if:

3. For each variableDefinition in variableDefinitions:

So with current spec text if you don't have any variableDefinition any value would work.

Moreover:

Let value be the value provided in variableValues for the name variableName.

There are no references to variableValues being object it just should match a name to a value in some way.

[RubenGamarrarodriguez-tomtom]

When using application/json' for the request. (Or if one is using GraphQL over HTTP, providing the header 'Content-Type: application/json'

The whole request has to be valid JSON.
{..., "variables": "{}" ...} Might be considered valid.
Where:
{..., "variables": {} ...} Might fail. Which I see as expected, meaning it seems to me as not a bug of the implementation.