Super Enum Factory: SEnum(list)

Enums are great, for reducing a list of values, keys, labels, etc

In computer programming, an enumerated type (also called enumeration or enum, or factor in the R programming language, and a categorical variable in statistics) is a data type consisting of a set of named values called elements, members or enumerators of the type. https://en.wikipedia.org/wiki/Enumerated_type

You should always use enums when a variable (especially a method parameter) can only take one out of a small set of possible values. Examples would be things like type constants (contract status: "permanent", "temp", "apprentice"), or flags ("execute now", "defer execution"). http://stackoverflow.com/a/4709224/194105

You end up with values which are smaller, so less goes into your database, and less "over the wire", from server to client and back.

The translation from values to labels is all in very small application code, cached on the client.

Install

npm install --save s-enum

Terms

• key should be a camelCase string selector for any node.
• if you provide one, we don't do anything to it
• if you do not provide one, we attempt to translate label to camelCase
• value can be anything... usually a number or string or function
• if you don't provide one, we attempt to create a numerical value incrementing from 0
• label should be a human readable string
• if you don't provide one, we use key

Usage Example: Days of the Week (basics)

First you create your enum object... this can happen anywhere

var Days = SEnum([
  "Sunday",
  "Monday",
  "Tuesday",
  "Wednesday",
  "Thursday",
  "Friday",
  "Saturday"
]);

// now you can access:
Days.values() === [0, 1, 2, 3, 4, 5, 6];
Days.keys() === ["sunday", "monday", "tuesday", "wednesday", "thursday", "friday", "saturday"];
Days.labels() === ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];
Days.options() === {0: "Sunday", 1: "Monday", 2: "Tuesday", 3: "Wednesday", 4: "Thursday", 5: "Friday", 6: "Saturday"};

// and via aliases on the value
Days.0.label === "Sunday";
Days.0.key === "sunday";
Days.0.value === 0;

// and via aliases on the key
Days.sunday.label === "Sunday"
Days.sunday.key === "sunday"
Days.sunday.value === 0;

// and use a get() to return any specific field, from value or key
Days.get("sunday", "value") === 0;
Days.get(0, "label") === "Sunday";
Days.get("not-found", "value", "defaultValue") === "defaultValue";

Usage Example: Status

First you create your enum object... this can happen anywhere, but in this example we are going to think about attaching this to an Object (a data model / Collection object).

Tasks.Statuses = SEnum([
  { key: "submitted", value: 1,  label: "Submitted",
    icon: "fa fa-check" },
  { key: "accepted",  value: 2,  label: "Accepted",
    icon: "fa fa-check-circle" },
  { key: "completed", value: 31, label: "All Done Yo",
    icon: "fa fa-check-square", finished:  true }
]);

// NOTE in additiion to the basics above, you can get to any field configured

Tasks.Statuses.get("submitted", "icon") === "fa fa-check";
Tasks.Statuses.get(1, "icon") === "fa fa-check";
Tasks.Statuses.get(31, "finished") === true;
Tasks.Statuses.get(1, "finished") === undefined;
Tasks.Statuses.get(1, "finished", "defaultValue") === "defaultValue";

// and via aliases on the value
Tasks.Statuses.1.icon === "fa fa-check";
Tasks.Statuses.submitted.icon === "fa fa-check";

Integrating into Meteor (optional)

When this was originally written, it was for a MeteorJS application. The following logic is how you can automatically translate/transform inputs into SEnum values before writing to the database. You can also validate to only allow these values.

If you want, you can setup a simple-schema to only allow values from the SEnum.

// allow all values
allowedValues: Tasks.Statuses.values(),
// or allow all values AND all keys [1, 2, 31, "submitted", "accepted", "completed"]
allowedValues: Tasks.Statuses.values().concat(Tasks.Statuses.keys()),

You can setup a transform, translating all keys & labels into values

If you want to, you can setup a Mongo.Collection transform This will allow a user to pass in any value or key, and verify that it's got a valid, value; if not it changes to 0.

Tasks = new Mongo.Collection('tasks', {
  transform:  function(doc) {
    if (_.has(doc, "status")) {
      doc.status = Tasks.Statuses.value(doc.status, 0);
    }
    return doc;
  }
});

If you're using autoform/schemas you can setup autoValue something like the following.

This will allow a user to pass in any value or key, and verify that it's got a valid, value; if not it unsets... (you could choose not to unset, and instead get validation errors based on allowedValues).

status: {
  type: Number,
  optional: true,
  autoValue: function() {
    var autoFormField = this.field("status");
    if (!autoFormField.isSet) {
      this.unset();
      return;
    }
    var status = Tasks.Statuses.value(autoFormField.value);
    if (typeof status === "undefined") {
      this.unset();
      return;
    }
    return status;
  }
}

And for any template, you can easily translate value -> label or any value -> any other field...

This allows some fancy and simple comparable translations.

Template.Example.helpers({

  // value -> label
  status: function() {
    return Tasks.Statuses.label(this.status);
  },

  // value -> <i> font awesome icon (with default=?)
  statusIcon: function() {
    var icon = Tasks.Statuses.get(this.status, "icon");
    if (!icon) {
      icon = "fa fa-question";
    }
    return '<i class="' + icon '"></i>';
  },

  // value -> <span class="label {{finished?}}"><i> text
  statusLabelAndIcon: function() {
    var label = Tasks.Statuses.label(this.status, "Unknown");
    var icon = Tasks.Statuses.get(this.status, "icon");
    if (!icon) {
      icon = "fa fa-question";
    }
    var finished = Tasks.Statuses.get(this.status, "finished");
    var className = finished ? 'success' : 'default';
    return '<span class="label label-' + className + '">' +
      '<i class="' + icon '"></i> ' + label +
      '</span>';
  }
});

TODO / Roadmap

• [x] Construct support for full nodes, simple [value, ...] lists, and {value: lable, ...} lists
• [x] Object helper methods: keys(), values(), labels()
• [x] Object helper methods: get(), value(), label()
• [x] Fully tested
• [x] README w/ real world usage examples
• [ ] Meteor ui helper (maybe as extra optional package) {{SEnum status Tasks.Statuses}}