json2java.js

function generatePojoClass(json) {
    return parseObj(json, "MyClass");
}

function getJavaType(jsonType, key, value) {
    switch (jsonType) {
        case 'String':
            return 'String';
        case 'Long':
            return 'Long';
        case 'Double':
            return 'Double';
        case 'Boolean':
            return 'Boolean';
        case 'Object':
            return toClazzName(key);
        case 'Array':
            if (value.length === 0) {
                return 'List<Object>';
            } else {
                let arrayJsonTypes = new Set(value.map(v => getJsonType(v)));


                let arrayJavaType = arrayJsonTypes.has("Array") ? getJavaType("Array", key, value[0]) :
                    arrayJsonTypes.has("Object") ? "Object" :
                        arrayJsonTypes.has("String") ? "String" :
                            arrayJsonTypes.has("Double") ? "Double" :
                                arrayJsonTypes.has("Long") ? "Long" :
                                    "Boolean";

                return `List<${arrayJavaType}>`;
            }
    }
}

function parseObj(json, className) {
    let parsed = JSON.parse(json);
    //todo try to fix arrays in json like map them to same type
    let keys = Object.keys(parsed);
    let classBody = "";

    let additionalClasses = "";
    keys.forEach((key) => {
        let value = parsed[key];
        let jsonType = getJsonType(value);
        let javaType = getJavaType(jsonType, key, value);

        if (jsonType === 'Object') {
            let innerClass = parseObj(JSON.stringify(value), javaType);
            additionalClasses += innerClass;
        }

        classBody += `    private final ${javaType} ${camelCase(key)};\n`;
    });

    let mainClass = `class ${className} {\n${classBody}}`;

    return mainClass + "\n" + additionalClasses;
}

function getJsonType(value) {
    if (typeof value === 'string') {
        return 'String';
    } else if (Array.isArray(value)) {
        return 'Array';
    } else if (typeof value === 'number') {
        if (Number.isInteger(value)) {
            return 'Long';
        } else {
            return 'Double';
        }
    } else if (typeof value === 'boolean') {
        return 'Boolean';
    } else if (typeof value === 'object') {
        return 'Object';
    }
}

function toClazzName(str) {
    let key = camelCase(str)
    return key.charAt(0).toUpperCase() + key.slice(1);
}

function camelCase(str) {
    str = str.replace("-", " ")
    str = str.replace("_", " ")
    return str
        .replace(/\s(.)/g, function (a) {
            return a.toUpperCase();
        })
        .replace(/\s/g, '')
        .replace(/^(.)/, function (b) {
            return b.toLowerCase();
        });
}

export default generatePojoClass;

import generatePojoClass from "./PojoGenerator";

test('flat json', () => {
let input =
{ "oldestTransactionDate": "2022-08-01", "latestTransactionDate": "2023-06-30", "bankName": "CAPITAL ONE BANK", "id": "a047eb08-a564-3b10-96d6-1cc90ef91103", "source": "Bank Statement", "accountNumber": "2082743025" }

const expectedOutput =

class MyClass { private final String oldestTransactionDate; private final String latestTransactionDate; private final String bankName; private final String id; private final String source; private final String accountNumber; }
const result = generatePojoClass(input);
expect(result.trim()).toBe(expectedOutput.trim());
});

test('flat json camel case chekc', () => {
let input =
{ "oldest_TransactionDate": "2022-08-01", "latestTransactionDate": "2023-06-30", "bank-Name": "CAPITAL ONE BANK", "id": "a047eb08-a564-3b10-96d6-1cc90ef91103", "source": "Bank Statement", "account-Number": "2082743025" }

const expectedOutput =
    `class MyClass {
private final String oldestTransactionDate;
private final String latestTransactionDate;
private final String bankName;
private final String id;
private final String source;
private final String accountNumber;

}`
const result = generatePojoClass(input);
expect(result.trim()).toBe(expectedOutput.trim());
});

test('flat json with double and long', () => {
let input =
{ "oldestTransactionDate": "2022-08-01", "latestTransactionDate": "2023-06-30", "bankName": "CAPITAL ONE BANK", "doubleMeme": 1.1, "doubleMemeLong": 1, "id": "a047eb08-a564-3b10-96d6-1cc90ef91103", "source": "Bank Statement", "accountNumber": "2082743025" }

const expectedOutput =
    `class MyClass {
private final String oldestTransactionDate;
private final String latestTransactionDate;
private final String bankName;
private final Double doubleMeme;
private final Long doubleMemeLong;
private final String id;
private final String source;
private final String accountNumber;

}`
const result = generatePojoClass(input);
expect(result.trim()).toBe(expectedOutput.trim());
});

test('flat json with arrays', () => {
let input =
{ "oldestTransactionDate": "2022-08-01", "latestTransactionDate": "2023-06-30", "bankName": "CAPITAL ONE BANK", "doubleMeme": 1.1, "doubleMemeLong": 1, "doubleMemeLongArr": [1,2,3], "doubleMemeLongArrDouble": [1.1,2.2,3.0], "strArr": ["1.1","2.2","3.0", "false"], "id": "a047eb08-a564-3b10-96d6-1cc90ef91103", "source": "Bank Statement", "accountNumber": "2082743025" }

const expectedOutput =
    `class MyClass {
private final String oldestTransactionDate;
private final String latestTransactionDate;
private final String bankName;
private final Double doubleMeme;
private final Long doubleMemeLong;
private final List<Long> doubleMemeLongArr;
private final List<Double> doubleMemeLongArrDouble;
private final List<String> strArr;
private final String id;
private final String source;
private final String accountNumber;

}`
const result = generatePojoClass(input);
expect(result.trim()).toBe(expectedOutput.trim());
});

test('flat json with array of arrays', () => {
let input =
{ "oldestTransactionDate": "2022-08-01", "latestTransactionDate": "2023-06-30", "bankName": "CAPITAL ONE BANK", "doubleMeme": 1.1, "doubleMemeLong": 1, "doubleMemeLongArr": [1,2,3], "doubleMemeLongArrDouble": [1.1,2.2,3.0], "strArr": ["1.1","2.2","3.0", "false"], "arrOfArr": [["1.1"],["2.2","3.0"], ["false"]], "arrOfArrOfArr": [[["1.1"]],[["2.2"],["3.0"]], [["false"]]], "arrOfArrDiffTypes": [[[1.1]],[["2.2"],["3.0"]], [["false"]]], "id": "a047eb08-a564-3b10-96d6-1cc90ef91103", "source": "Bank Statement", "accountNumber": "2082743025" }

const expectedOutput =
    `class MyClass {
private final String oldestTransactionDate;
private final String latestTransactionDate;
private final String bankName;
private final Double doubleMeme;
private final Long doubleMemeLong;
private final List<Long> doubleMemeLongArr;
private final List<Double> doubleMemeLongArrDouble;
private final List<String> strArr;
private final List<List<String>> arrOfArr;
private final List<List<List<String>>> arrOfArrOfArr;
private final List<List<List<Double>>> arrOfArrDiffTypes;
private final String id;
private final String source;
private final String accountNumber;

}`
const result = generatePojoClass(input);
expect(result.trim()).toBe(expectedOutput.trim());
});

test('flat json with simple object', () => {
let input =
{ "godObj": { "field1": "1", "field2": 2, "field3": 2.2 }, "oldestTransactionDate": "2022-08-01", "latestTransactionDate": "2023-06-30", "bankName": "CAPITAL ONE BANK", "doubleMeme": 1.1, "doubleMemeLong": 1, "doubleMemeLongArr": [1,2,3], "doubleMemeLongArrDouble": [1.1,2.2,3.0], "strArr": ["1.1","2.2","3.0", "false"], "arrOfArr": [["1.1"],["2.2","3.0"], ["false"]], "arrOfArrOfArr": [[["1.1"]],[["2.2"],["3.0"]], [["false"]]], "arrOfArrDiffTypes": [[[1.1]],[["2.2"],["3.0"]], [["false"]]], "id": "a047eb08-a564-3b10-96d6-1cc90ef91103", "source": "Bank Statement", "accountNumber": "2082743025" }

const expectedOutput =
    `class MyClass {
private final GodObj godObj;
private final String oldestTransactionDate;
private final String latestTransactionDate;
private final String bankName;
private final Double doubleMeme;
private final Long doubleMemeLong;
private final List<Long> doubleMemeLongArr;
private final List<Double> doubleMemeLongArrDouble;
private final List<String> strArr;
private final List<List<String>> arrOfArr;
private final List<List<List<String>>> arrOfArrOfArr;
private final List<List<List<Double>>> arrOfArrDiffTypes;
private final String id;
private final String source;
private final String accountNumber;

}
class GodObj {
private final String field1;
private final Long field2;
private final Double field3;
}`
const result = generatePojoClass(input);
expect(result.trim()).toBe(expectedOutput.trim());
});