Improve data marshaling between Perl and GraphQL

[stevan]

We need to be able to marshal our input data from Perl. Currently we handle simple scalar type literals for input (ex: query { setName(10, "Alice") }), but we cannot handle complex types like lists, object literals or Schema::InputObject types (ex: query { setAttr({ "id" : 10, "name" : "Bob" }) }).

AST nodes

We need to improve the type checking of Literal values in AST nodes, this is covered with issue #15.

The AST nodes for the complex types are actually already defined, we just do not handle the conversion of these types into Perl values.

Graph::QL::AST::Node::ListValue
    values => [ Graph::QL::AST::Node::Role::Value ]

Graph::QL::AST::Node::ObjectValue
    fields => [ 
        Graph::QL::AST::Node::ObjectField {
             name  => Graph::QL::AST::Node::Name
             value => Graph::QL::AST::Node::Role::Value
        }
    ]

AST to Perl Literal conversion

Our existsing conversions between AST nodes and Perl literals is pretty sloppy, you can see this if you look at the comments in the Graph::QL::Util::AST package.

Here is the Input Values section of the spec, which basically tells us exactly what we need to do.

Validation & Internal representations

Here is the spec from the Schema point of view, which include information like parsing input, coercions, etc.

Tests

An example test case for more complex input to arguments is currently commented out, but can be added.

See Also

This code can also be referred to for "inspiration":

• https://github.com/graphql/graphql-js/blob/master/src/utilities/valueFromAST.js#L25-L44
• https://github.com/graphql/graphql-js/blob/master/src/utilities/valueFromASTUntyped.js#L16-L31

Related Issues

This is related to the Schema::InputObject work in #28 in that it is about parsing argument input data, but InputObjects are just an extra layer, so not critical (hence the separate ticket).