Constructor on typescript enum?

Question

We have a situation at the moment with our code where we are using Enums in our Java layer which store an id and a 'display value' with a constructor like below:

public enum Status implements EnumIdentity {

    Active(1, "Active"),
    AwaitingReview(2, "Awaiting Review"),
    Closed(3, "Closed"),
    Complete(4, "Complete"),
    Draft(5, "Draft"),
    InProcess(6, "In Process"),
    InReview(7, "In Review"),
    NotStarted(8, "Not Started"),
    PendingResolution(9, "Pending Resolution"),
    Rejected(10, "Rejected");

    private int id;
    private String displayValue;

    PlanStatus(final int id, String displayValue) {
        this.id = id;
        this.displayValue = displayValue;
    }

    /** {@inheritDoc} */
    @Override
    public int id() {
        return id;
    }

    public String getDisplayValue() {
        return displayValue;
    }
}

and we would like something in typescript to match this to allow for displaying the status in a meaningful way for carrying out logic and for display the value to the user on the front end. Is this possible? Is there a better way to handle this? We would like to avoid having to use logic such as does status.id() = 1 or status.name() = 'Active' hence for the push towards enums.

Thanks

Try take a look at typescriptlang.org/docs/handbook/enums.html hope this helps. — Swoox
– Swoox, Commented Dec 8, 2017 at 12:30

Titian Cernicova-Dragomir · Accepted Answer · 2017-12-08 15:28:46Z

33

Typescript does not support expanded enums such as in java. You can achieve a similar effect using a class:

interface EnumIdentity { }
class Status implements EnumIdentity {

    private static AllValues: { [name: string] : Status } = {};

    static readonly Active = new Status(1, "Active");
    static readonly AwaitingReview = new Status(2, "Awaiting Review");
    static readonly Closed = new Status(3, "Closed");
    static readonly Complete = new Status(4, "Complete");
    static readonly Draft = new Status(5, "Draft");
    static readonly InProcess = new Status(6, "In Process");
    static readonly InReview = new Status(7, "In Review");
    static readonly NotStarted = new Status(8, "Not Started");
    static readonly PendingResolution = new Status(9, "Pending Resolution");
    static readonly Rejected = new Status(10, "Rejected");

    private constructor(public readonly id: number, public readonly displayValue: string) {
        Status.AllValues[displayValue] = this;
    }

    public static parseEnum(data: string) : Status{
        return Status.AllValues[data];
    }

}

edited Dec 8, 2017 at 15:28

answered Dec 8, 2017 at 12:05

Titian Cernicova-Dragomir

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8 Comments

Rebecca Douglas Over a year ago

That's a shame, I was coming to that conclusion but thought it best to post out to the community in case someone found a similar way of working around this. Thanks

Rebecca Douglas Over a year ago

How will a json string like this {"id":1, "title":"Test","status":"AwaitingReview"}] map to a class when the status gets represented as a string?

Titian Cernicova-Dragomir Over a year ago

That will be a manual affair I'm afraid. You will need to use the parseEnum method o added to convert to the enum ..

Rebecca Douglas Over a year ago

I would never have thought how to do this, how is the AllValues defined, spitting out an error on me?

blau Over a year ago

Thanks for the answer - I am newer to TS, but have many years of Java under my belt and I asked my team this question in our last session together. I'm not sure if anyone knew exactly what I was asking because of differences in abilities, but this answered it perfectly.

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