Overriding Models

Swagger uses reflection to understand the models that are required as either input parameters or model attributes. For instance, a User object might have an Address attribute. Swagger will attempt to introspect the entire object hierarchy so that all aspects of the model can be provided to the consumer.

You can control what the Swagger introspection code sees with Swagger's own ApiProperty, using JAXB, or even @JsonIgnore annotations. When you use 3rd party or even generic Java objects, this can get tricky as you may not want all aspects of the model being represented in the Swagger JSON. For example, take java.util.Date.

By default, the Date object will be introspected from public methods, and look something like this:

"Date": {
  "id": "Date",
  "properties": {
    "time": {
      "type": "long"
    },
    "minutes": {
      "type": "int"
    },
    "seconds": {
      "type": "int"
    },
    "hours": {
      "type": "int"
    },
    "month": {
      "type": "int"
    },
    "year": {
      "type": "int"
    },
    "timezoneOffset": {
      "type": "int"
    },
    "day": {
      "type": "int"
    },
    "date": {
      "type": "int"
    }
  }
}

Now you probably don't want the client to build it's own Date object from this description. If you, for instance, have configured your API to send the date in ISO-8601 format, the consumer probably wants to know that the date is coming as a string format. Thus, you really want your Date to serialize like such:

"Date": {
  "id": "Date",
  "properties": {
    "value": {
      "required": true,
      "description": "Date in ISO-8601 format",
      "notes": "Add any notes you like here",
      "type": "string"
    }
  }
}

This can be done by telling the model introspector to avoid reflecting over java.util.Date and instead to use a prescribed model representation:

import com.wordnik.swagger.core.util.JsonUtil;
import com.wordnik.swagger.core.*;

import com.fasterxml.jackson.databind.*;

import java.io.IOException;

public class DateSerializer {
  public DateSerializer() {
    try{
      String jsonString = "\n" +
        "{\n" +
        "  \\"name\\": \\"Date\\",\n" +
        "  \\"fields\\": [\n" +
        "    {\n" +
        "      \\"name\\": \\"value\\",\n" +
        "      \\"description\\": \\"Date in milliseconds since epoch\\",\n" +
        "      \\"notes\\": \\"Add any notes you like here\\",\n" +
        "      \\"paramType\\": \\"long\\",\n" +
        "      \\"required\\": true,\n" +
        "      \\"allowMultiple\\": false\n" +
        "    }\n" +
        "  ]\n" +
        "}\n";

      DocumentationObject m = JsonUtil.getJsonMapper().readValue(jsonString, DocumentationObject.class);
      String className = java.util.Date.class.getName();
      ApiPropertiesReader.add(className, "Date", m);
    }
    catch (IOException e){
      // handle this, of course!
      e.printStackTrace();
    }
  }
}

This needs to be fired on startup of the app, typically in a bootstrap servlet. Now whenever a java.util.Date is encountered by Swagger, it will use this definition.