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marcinluczynski's avatar
New Contributor
3 years ago

Generated Java endpoints for array body

I have a following parameter definition in a PATCH request:

- name: patch_request
in: body
required: true
$ref: '#/definitions/JSONResourcePatchRequestModel'

The object in $ref is the following:

type: array
$ref: '#/definitions/JSONResourcePatchModel'

Which is converted as expected into the following model class:

public class JSONResourcePatchRequestModel extends ArrayList<JSONResourcePatchModel> implements Serializable{

The API Java method generated by old Swagger looks like this:

Response updateConnection(@ApiParam(value = "Fields to update within the connection." ,required=true) JSONResourcePatchRequestModel patchRequest)

However the very same swagger.yaml and model definitions when passed through Swagger 3.0 result with a slight change:

Response updateConnection(@Parameter(in = ParameterIn.DEFAULT, required=true) List<JSONResourcePatchModel> body)

So instead of a class put as a schema ref, we get its base type (the one that it actually extends). My hunch says that that's the cause of the error that occurs when API gets tested:

Caused by: java.lang.ClassCastException: java.util.LinkedHashMap incompatible with

Apparently the type that's supposed to be there is not exactly the same as expected, Jackson mapper has a problem with proper deserialization of a request so it goes to its fallback which means all the body's JSON content gets mapped into ArrayList<LinkedHashMap> type of the object and it causes the exception.

Why the change? Why would this method simply not receive JSONResourcePatchRequestModel type for the body content?

1 Reply

  • I found the root cause. This behavior is observed with 3.0 libraries and codegen, but with 2.0 version provided in the yaml template.