Typescript Deserializer

A typescript based JSON deserializer that permits converting raw Javascript/JSON Objects into typescript classes. Using decorators it becomes simple to define which class members should be deserialized and optionaly mapped into different values.

Goals

• Class deserialization from raw Javascript/JSO Objects
• Class member deserialization using decorator for greater flexibility
• Allow key transformation to change those snake_cases into camelCases
• Allow value transformation for automatic convertions and calculations

Installation

Via yarn

yarn add typescript-deserializer

Via npm

npm install typescript-deserializer

Usage

Import

import { JsonProperty, Deserializer } from 'typescript-deserializer';

Simple usage

import { JsonProperty, Deserializer } from 'typescript-deserializer';

class ExampleClass {
    @JsonProperty()
    public prop1: string;
}

const instance = Deserializer.deserialize<ExampleClass>(ExampleClass, { prop1: 'Example Prop 1' });

instance.prop1;
// → "Example Prop 1"

Key transformation

import { JsonProperty, Deserializer } from 'typescript-deserializer';

class ExampleClass {
    @JsonProperty({ jsonKey: 'ugly_prop' })
    public prop2: string;
}

const instance = Deserializer.deserialize<ExampleClass>(ExampleClass, { ugly_prop: 'Example Prop 2' });

instance.prop2;
// → "Example Prop 2"

Value transformation

import { JsonProperty, Deserializer } from 'typescript-deserializer';

class ExampleClass {
    @JsonProperty({
        map: (value: string) => parseInt(value, 10),
    })
    public prop3: number;
}

const instance = Deserializer.deserialize<ExampleClass>(ExampleClass, { prop3: '33' });

instance.prop3;
// → 33

typeof instance.prop3;
// → "number"

Ignoring properties without decorators

import { JsonProperty, Deserializer } from 'typescript-deserializer';

class ExampleClass {
    public prop4: string;
}

const instance = Deserializer.deserialize<ExampleClass>(ExampleClass, { prop4: 'Example Prop 4' });

instance.prop4;
// → undefined

Preserving default values

import { JsonProperty, Deserializer } from 'typescript-deserializer';

class ExampleClass {
    @JsonProperty()
    public prop5: string = 'Awesome Default Value';
}

const instance = Deserializer.deserialize<ExampleClass>(ExampleClass, { otherProp: 'Other Example Prop' });

instance.prop5;
// → "Awesome Default Value"

Deserialize function has static method

import { JsonProperty, Deserializer } from 'typescript-deserializer';

class ExampleClass {
    @JsonProperty()
    public prop6: string;

    static deserialize (jsonObject: Object): ExampleClass {
        return Deserializer.deserialize<ExampleClass>(ExampleClass, jsonObject);
    }
}

const instance = ExampleClass.deserialize({ prop6: 'Example Prop 6' });
instance.prop6;

// → "Example Prop 6"

Deserialize function has static method

import { JsonProperty, Deserializer } from 'typescript-deserializer';

class ExampleClass {
    @JsonProperty()
    public prop6: string;

    static deserialize (jsonObject: Object): ExampleClass {
        return Deserializer.deserialize<ExampleClass>(ExampleClass, jsonObject);
    }
}

const instance = ExampleClass.deserialize({ prop6: 'Example Prop 6' });
instance.prop6;

// → "Example Prop 6"

Built in mapping functions

import { JsonProperty, Deserializer } from 'typescript-deserializer';

class ExampleClass {
    @JsonProperty({
        map: Deserializer.toDate,
    })
    public prop7: Date;

    @JsonProperty({
        map: Deserializer.parseInt,
    })
    public prop8: number;

    @JsonProperty({
        map: Deserializer.fromArray(OtherClass.deserialize),
    })
    public prop9: Array<OtherClass>;

    static deserialize (jsonObject: Object): ExampleClass {
        return Deserializer.deserialize<ExampleClass>(ExampleClass, jsonObject);
    }
}

const instance = ExampleClass.deserialize({
    prop7: '1995-12-17T03:24:00',
    prop8: '123',
    prop9: [
        { (...) },
        { (...) },
        { (...) },
    ],
});

instance.prop7;
// → Sun Dec 17 1995 03:24:00 GMT...

typeof instance.prop7;
// → "Object" ~ Date

instance.prop8;
// → 123

typeof instance.prop8;
// → "number"

instance.prop9;
// → [ <OtherClass>, <OtherClass>, <OtherClass> ]

Building/Testing

• Runs linter and tests with:

yarn test

• Builds library and types:

yarn build

TODO

• [ ] Remove @loopback/metadata dependency