simplymequeeny/json-string-schema-generator

Generates JSON Schema based from JSON data using JAVA

json-string-schema-generator

Generates JSON Schema or POJO based from JSON data using JAVA

Motivation

I have been googling a lot to find a library in JAVA that would generate me a JSON Schema based on the JSON data I have. But most of the libraries I found need to have a JAVA class in order to generate a JSON schema. So I made a simple JSON Schema Generator based on JSON data. If there is a library that already exists please let me know (via posting an Issue here) and I will be happy to use it in the current project I am working on. Thanks!

Features

1. Generates JSON Schema (output as String or File)
2. Generates POJOs

Usage

Just call the static method JsonSchemaGenerator.outputAsString or JsonSchemaGenerator.outputAsFile

public class GenerateSchema {
    public static void main(String[] args) throws IOException {
        String json = "{\"sectors\": [{\"times\":[{\"intensity\":30," +
                "\"start\":{\"hour\":8,\"minute\":30},\"end\":{\"hour\":17,\"minute\":0}}," +
                "{\"intensity\":10,\"start\":{\"hour\":17,\"minute\":5},\"end\":{\"hour\":23,\"minute\":55}}]," +
                "\"id\":\"dbea21eb-57b5-44c9-a953-f61816fd5876\"}]}";
        String result = JsonSchemaGenerator.outputAsString("Schedule", "this is a test", json);
            /* sample output
            {
              "title": "Schedule",
              "description": "this is a test",
              "type": "object",
              "properties": {
                "sectors": {
                  "type": "array",
                  "items": {
                    "properties": {
                      "times": {
                        "type": "array",
                        "items": {
                          "properties": {
                            "intensity": {
                              "type": "number"
                            },
                            "start": {
                              "type": "object",
                              "properties": {
                                "hour": {
                                  "type": "number"
                                },
                                "minute": {
                                  "type": "number"
                                }
                              }
                            },
                            "end": {
                              "type": "object",
                              "properties": {
                                "hour": {
                                  "type": "number"
                                },
                                "minute": {
                                  "type": "number"
                                }
                              }
                            }
                          }
                        }
                      },
                      "id": {
                        "type": "string"
                      }
                    }
                  }
                }
              } 
            }
             */

        // To generate JSON schema into a file
        JsonSchemaGenerator.outputAsFile("Schedule", "this is a test", json, "output-schema.json");
        
        // To generate POJO(s)
        JsonSchemaGenerator.outputAsPOJO("Schedule", "this is a test", json, "com.example", "generated-sources");
    }
}

Author

• Quennie Teves - initial work

Built With

1. Java 8
2. Jackson Databind
3. JSON Schema Validator
4. jsonschema2pojo

License

This project is licensed under the MIT License - see the LICENSE file for details

json-string-schema-generator's Issues

type:string missing

Hi, i am a user of this project.
i realized that if I add below....

{
"vegetables":
{
"veggieName": "potato",
"size":[""]
}

}

generated schema looks like this..

{
"title": "test",
"description": "new test",
"type": "object",
"properties": {
"vegetables": {
"type": "object",
"properties": {
"veggieName": {
"type": "string"
},
"size": {
"type": "array",
"items": {
"properties":{}
}
},
}
},
}
}

the items don't have --type:object -- and
unnecessary commas also be located

If Type Array is empty then it is failing.

For Example if my input JSON is below :
{
"metadata": {
"properties": []
}
}
Then schema is not generating properly . we are getting below exception
"main" java.lang.NullPointerException.
Because in code we have taken directly
node = jsonNode.get(key).get(0);

Do you have any solution for this ?

Current implemenation is not having support for adding "additionalProperties" field in schema