Tips on utilizing knockout validation

I stumbled upon this source for creating validations.

However, I am struggling to grasp the concept of implementing the extend method in my code.

I populate my observable with data received from a Breeze query.

The loading process looks like this:

dataObsArray = ko.observableArray()

datacontext.getData(id, dataObsArray)
                   .then(function () {

          // some logic


 })
        .fail("Data not found");

Subsequently, I connect this observable array to my view in the following way:

<tbody data-bind="with: dataObsArraay">
            <tr>
                <td>name</td>
                <td> <input data-bind="  value: Name" ></td>
                <td> <input data-bind="  value: Age" ></td>

            </tr>
</tbody>

Given this setup, I am confused about the implementation of the extend method since I am simply binding my view to the properties in the observable array.

I would greatly appreciate any guidance on this matter.

Answer №1

If you're tired of putting validation logic in your UI code using knockout extenders, consider utilizing breeze validation instead. By using breeze validation, you can ensure that rules are always evaluated and avoid the need to create an additional model for validation purposes.

Here's an example of how to use breeze's built-in stringLength validator:

var entityType = entityManager.metadataStore.getEntityType('????'),
    nameProperty = entityType.getProperty('Name'),
    nameLengthValidator = breeze.Validator.stringLength({ maxLength: 10, minLength: 2 });
nameProperty.validators.push(nameLengthValidator);

For a custom required validator that prevents whitespace-only values for strings, you can create and register a validator like this:

// make a reusable validator
var myRequiredValidator = breeze.Validator.makeRegExpValidator(
    "myRequiredValidator",  
    /\S/,  
    "The %displayName% '%value%' cannot be blank or entirely whitespace");

// register it with the breeze Validator class.
breeze.Validator.register(myRequiredValidator);

// add the validator to the Name property...
var entityType = entityManager.metadataStore.getEntityType('????'),
    nameProperty = entityType.getProperty('Name');
nameProperty.validators.push(nameLengthValidator);

Take a look at the documentation for creating regex validators. Additionally, you can develop custom validators by referring to the breeze docs and exploring the Write a custom validator section.

Answer №2

To effectively organize your information, it is recommended to establish a model for your dataset. Here is an example:

function individual(name, age) {
    this.name = ko.observable(name).extend({ minLen: 2, maxLen: 10 });
    this.age = ko.observable(age).extend({ minimum: 18, maximum: 99 });
}

var dataset = [],
    individualsList = ko.observableArray();

datacontext.getData(identity, dataset)
    .then(function (dataset) {
        for (x = 0; x < dataset.length; x++) {
            individualsList.push(new individual(dataset.Name, dataset.Age));
        }
    })
    .fail("Information not located");

<tbody data-bind="foreach: individualsList">
    <tr>
        <td>name</td>
        <td> <input data-bind="  value: name" ></td>
        <td> <input data-bind="  value: age" ></td>
    </tr>
</tbody>

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