Why is my ReadyAPI Swagger Complience Assertion failing

We are building a bunch of APIs and coming into a strange issue when testing them.

In our swagger file we have the following:

"CustomerAddress": {
    "type": "object",
    "properties": {
        "id": {
            "$ref": "#/components/schemas/StringSettable"
        },

And this references the following:

"StringSettable": {
    "type": "object",
    "properties": {
        "hasValue": {
            "type": "boolean"
        },
        "value": {
            "type": "string",
            "nullable": true
        }
    },
    "additionalProperties": false
},

This all looks OK to us but when we run a ReadyAPI test we get the following error:

instance type (string) does not match any allowed primitive type (allowed ["object"]) checked node: [/id] corresponding schema: [/properties/id]

This is the response payload in JSON:

{
         "id" : "thisisanid",
         "flat" : "Flat",
         "buildingName" : "Building",
         "houseNumber" : 11,
         "addressLine1" : "Line 1",
         "addressLine2" : "Line 2",
         "town" : "Town",
         "county" : "County",
         "locality" : "Locality",
         "district" : "District",
         "postcode" : "TE57 ING",
         "validFrom" : null,
         "country" : "United Kingdom",
         "isForeignAddress" : false,
         "isUnknownAddress" : false,
         "addressType" : 1,
         "op" : "add"
      },

We have tried editting the Swagger to be the following:

"id": {
  "type": "string",
  "nullable": true
}

This then passes with no issues so not 100% sure where the assertion is being tripped up on this. Has anyone else encountered this?

The reason this is not working is:

id in the OpenAPI specification is defined as an object:

"StringSettable": {
    "type": "object", // <-- it's an object
    ...
}

but, id in the request payload is defined as a string:

{
    "id" : "thisisanid", // <-- it's a string
    ... 
}

In this context, the error message you are getting makes quite a lot of sense:

instance type (string) does not match any allowed primitive type (allowed ["object"])

If you want to fix this problem you have two choices. The first choice you have already discovered - redefine the id type in the OpenAPI specification.

The second choice is to change the request payload so that the schema definition is satisfied:

{
    "id" : { // <-- now it's an object!
         "hasValue": true,
         "value": "thisisanid"
    },
    ... 
}