The purpose of this repo is to demonstrate a problem that I ran into while trying to support
the OpenAPI oneOf feature in Go. Along with the description of the problem in this README,
the "deser_problem" package contains some example code along with a testcase that (hopefully) illustrates what I'm trying to accomplish.
In the problem I'm trying to solve, I have an example struct defined with two fields like this:
type Resource struct{
ID *string`json:"id" validate:"required"`
Info InfoIntf `json:"info,omitempty"`
}
plus three other structs:
type Info struct{
Foo *string`json:"foo,omitempty"`
Bar *string`json:"bar,omitempty"`
}
type Foo struct{
Foo *string`json:"foo" validate:"required"`
}
type Bar struct{
Bar *string`json:"bar" validate:"required"`
}
The "Info" field in the Resource struct models a schema property that uses "oneOf" (Info is expressed as being "one of" either Foo or Bar) and so in this example I want the user to be able to supply an instance of the Foo struct or an instance of the Bar struct wherever the Info struct is called for. So to accomplish this, I define an interface (InfoIntf) along with the Info, Foo and Bar structs which all "implement" the interface. This allows for the correct serialization of the Resource struct regardless of whether the Info field is a pointer to a Foo or a Bar.
Unfortunately (and unsurprisingly), the deserialization doesn't work because the default json deserializer doesn't know how to deserialize the "Info" field into the "InfoIntf" interface. To support the deserialization of a schema property that uses oneOf such as the "Resource.Info" field, we generate the "parent" Info struct (i.e. "parent" of both Foo and Bar) so that it contains the union of the properties found in the Foo and Bar structs. Assuming that we have a JSON string that represents a valid instance of the Resource schema (i.e. the "info" field contains either a "Foo" or "Bar" instance), we should be able to deserialize into the Info struct. The problem is that the default json deserializer gets tripped up because of the use of the interface (InfoIntf) when declaring the Info field (which is done to support the serialization side of the equation).
So... the crix of the problem is... how can I implement a custom deserializer/unmarshaller that will accomplish this?