Question

Has anyone written a utility that will convert Breeze metadata (captured from entity framework data attributes) into knockout validation extensions (using knockout.validation)?

Answer 1

I have made an function that reads the metadata from an entity and adds validation rules.

app.domain.indicador = (function () {
"use strict";
var constructor = function () {...}
var initializer = function indicadorInitializer(entity) {
    var entityType = entity.entityType;
    if (entityType) {
        console.log(entityType);
        for (var i = 0; i < entityType.dataProperties.length; i++) {
            var property = entityType.dataProperties[i];
            console.log(property);
            var propertyName = property.name;

            var propertyObject = entity[propertyName];
            if (!property.isNullable) {
                propertyObject.extend({ required: true });
            }
            if (property.maxLength) {
                propertyObject.extend({ maxLength: property.maxLength });
            }
        }

        for (var i = 0; i < entityType.foreignKeyProperties.length; i++) {
            var property = entityType.foreignKeyProperties[i];
            console.log(property);
            var propertyName = property.name;

            var propertyObject = entity[propertyName];
            if (!property.isNullable) {
                propertyObject.extend({ required: true });
            }
            if (property.maxLength) {
                propertyObject.extend({ maxLength: property.maxLength });
            }
            //Bussines rule
            propertyObject.extend({ notEqual: 0 });
        }
    }
};
return {
    constructor: constructor,
    initializer: initializer
};
})();

I use the function as initializer:

store.registerEntityTypeCtor("Indicador", domain.indicador.constructor, domain.indicador.initializer);

It’s just a start but for the time is useful for me.

Update:

I changed the way I add validation. I share it here in case it is useful to someone:

Helper object:

app.validatorHelper = (function (breeze) {
var foreignKeyInvalidValue = 0;

function addDataTypeRules(dataType, property) {
    switch (dataType) {
        case breeze.DataType.DateTime:
            //TODO: implement my function to validate dates. This validator is too permissive
            property.extend({ date: true });
            break;
        case breeze.DataType.Int64:
        case breeze.DataType.Int32:
        case breeze.DataType.Int16:
            //it's needed to accept negative numbers because of the autogenerated keys
            property.extend({ signedDigit: true });
            break;
        case breeze.DataType.Decimal:
        case breeze.DataType.Double:
        case breeze.DataType.Single:
            property.extend({ number: true });
            break;
    }
};

function addValidationRules(entity) {
    var entityType = entity.entityType;
    if (entityType) {
        for (var i = 0; i < entityType.dataProperties.length; i++) {
            var property = entityType.dataProperties[i];
            //console.log(property);
            var propertyName = property.name;
            var propertyObject = entity[propertyName];

            addDataTypeRules(property.dataType, propertyObject);

            if (!property.isNullable) {
                propertyObject.extend({ required: true });
            }
            if (property.maxLength) {
                propertyObject.extend({ maxLength: property.maxLength });
            }
        }

        for (var i = 0; i < entityType.foreignKeyProperties.length; i++) {
            var property = entityType.foreignKeyProperties[i];
            //console.log(property);
            var propertyName = property.name;
            var propertyObject = entity[propertyName];

            addDataTypeRules(property.dataType, propertyObject);

            if (!property.isNullable) {
                propertyObject.extend({ required: true });
                //Bussiness Rule: 0 is not allowed for required foreign keys
                propertyObject.extend({ notEqual: foreignKeyInvalidValue });
            }
            if (property.maxLength) {
                propertyObject.extend({ maxLength: property.maxLength });
            }
        }
    }
};

return {
    addValidationRules: addValidationRules
};
})(breeze);

The custom validator:

(function (ko) {
ko.validation.rules['signedDigit'] = {
    validator: function (value, validate) {
        if (!validate) return true;
        return ko.validation.utils.isEmptyVal(value) || (validate && /^-?\d+$/.test(value));
    },
    message: 'Please enter a digit'
};

ko.validation.registerExtenders();
})(ko);

Using the helper at the initializer:

app.domain.valorIndicador = (function (vHelper) {
"use strict";
var constructor = function () {
};

var initializer = function indicadorInitializer(entity) {
    vHelper.addValidationRules(entity);
};

return {
    constructor: constructor,
    initializer: initializer
};
})(app.validatorHelper);

And setting the initializer:

store.registerEntityTypeCtor("ValorIndicador", domain.valorIndicador.constructor, domain.valorIndicador.initializer);