thesimplevalidation

The simple validation service

Installation

npm install --save thesimplevalidation

Setup

There are paar steps to enable validation.

1. Create a model

interface IModel {
    title: string;
    description: string;
}

2. Create or use state, or something similar where we store user model values

this.model: IModel = {
    title: "",
    description: ""
};

3. Create validation model, validation errors model

import { ValidationModel } from "thesimplevalidation";

this.validation: ValidationModel<IModel> = {
    title: false,
    description: true
};

this.validationErrors: ValidationErrorsModel<IModel> = {
    title: [];
    description: [];
};

this.allValidationErrors: string [] = [];

this.isValid: boolean = false;

4. Creating Validation Scope

import { ValidationScope } from "thesimplevalidation";

const scope = new ValidationScope<IModel>({
    getModel: (): IModel => this.model
});

5. Add validators to model property(ies)

There are some built-in validators like RequiredValidator, MinValidator, MaxValidator, SimpleValidator, BooleanValidator. You can create own by yourself. It is easy. So. To add validators we use validation scope method useValidators.

import { RequiredValidator } from "thesimplevalidation";

this.scope.useValidators("title", new RequiredValidator());

6. Do validation

const result: IValidationResult<IModel> = await this.scope.isValid();
console.log(result.isValid, result); 
// -> false, { isValid: false, properties: { title: { isValid: false, errors: [] }, description: { isValid: true, errors: [] } }, errors: [] }

Usage

ValidationScope

This class is main point to define validation. Possible to define more than one scope in the form. As you wish.

const scope = new ValidationScope<IModel>({
    getModel: (): IModel => this.model
    onValidationChanged: async (result: IValidationResult<TModel>): Promise<void> => {
        const properties: Array<keyof TModel> = keys(result.properties) as Array<keyof TModel>;
        const validation: ValidationModel<TModel> = {} as ValidationModel<TModel>;
        const validationErrors: ValidationErrorsModel<TModel> = {} as ValidationErrorsModel<TModel>;

        for (const property of properties) {
            if (!result.properties.hasOwnProperty(property)) continue;
            
            validation[property] = result.properties[property].isValid;
            validationErrors[property] = result.properties[property].errors;
        }

        this.isValid = result.isValid;
        this.validation = validation;
        this.validationErrors = validationErrors;
        this.allValidationErrors = result.errors;
    }
});

getModel is invoked on validation by method isValid. onValidationChanged Optional. To handle validation result. It is invoked before isValid method is completed.

isValid

Validates the whole model.

const result: IValidationResult<IModel> = await this.scope.isValid();
console.log(result.isValid); // -> false

isPropertyValid

Validates only a specific property.

const propertyResult: IValidationPropertyResult = await this.scope.isPropertyValid("description");
console.log(propertyResult.isValid); // -> false

useValidators

Use this method to set validators for property.

this.scope.useValidators(
    "title", // property
    new RequiredValidator(), 
    new MaxValidator({ maxValue: () => 10 }),
    // add more validators if you need
);

useOriginal

You have built-in ability to check if the property has been changed or not. isDirty. To do it scope save a deep cloned copy of the model on init. When we invoke isDirty, then isDirty method compares value to saved copy. useOriginal resets saved cloned copy of model.

this.scope.useOriginal(newModel);

isPropertyDirty

The method of the validation scope allows to check if property has been changed (dirty).

this.model.title = "New Title";
let isTitleDirty: boolean = this.scope.isPropertyDirty("title");
console.log(isTitleDirty); // -> true

this.scope.useOriginal(this.model);
isTitleDirty = this.scope.isPropertyDirty("title");
console.log(isTitleDirty); // -> false

This method has optional key parameter. It uses to use nested value if property is object with nested object-properties. Example someProperty.someNestedProperty.key, arrayProperty.key.

getOriginalProperty

Gets property from saved cloned model.

const originalTitle = this.scope.getOriginalProperty("title");

isDirty

Checks if model or model properties have been changed (dirty).

Checks the whole model

this.scope.isDirty();

or checks only title property

this.scope.isDirty("title");

or checks multiple properties

this.scope.isDirty("title", "description");

Validators

You can create own validator using the followed template:

import { IValidationPropertyResult, IValidatorSetup, Validator } from "thesimplevalidation";

// if you need to pass extra data you can put here.
export interface IMyValidatorSetup<TModel, K extends keyof TModel> extends IValidatorSetup<TModel, K> {
    extraParam: () => number;
}

export class MyValidator<TModel, K extends keyof TModel> extends Validator<TModel, K, IMyValidatorSetup<TModel, K>> {
    constructor(setup: IMyValidatorSetup<TModel, K>) {
        super(setup);
    }

    public async isValidInternal(_value: TModel[K]): Promise<IValidationPropertyResult> {
        let isValid: boolean = true;

        //... add validation core here to set isValid

        return {
            isValid: isValid,
            errors: [] // You can add errors here, or use `setup.getErrors` method
        };
    }
}

IMyValidatorSetup<TModel, K>

The base options of validators.

isDisabled?: (value: TModel[K]) => boolean; is used to disable validator based on some logic-function. Could be nice if validation logic is depended on some values, logic, etc...

getErrors?: (value: TModel[K]) => string[]; is used to define error messages.

RequiredValidator

Validates property against "", null, undefined, 0, array.length.

MinValidator

Validates the minimum value of property.

Property value is a string then the validator checks the string length. If an array then the validator checks the array length. If a number then the validator validate against min value.

new MinValidator({
    minValue: () => 10
});

MaxValidator

Validates the maximum value of property.

Property value is a string then the validator checks the string length. If an array then the validator checks the array length. If a number then the validator validate against max value.

new MaxValidator({
    maxValue: () => 255
});

BooleanValidator

Validates if the model boolean property value is the same if some boolean value

new MaxValidator({
    target: () => true
});

SimpleValidator

The simpliest validator that option getValidation boolean value will be used as isValid of validation. The model property value is not used. See implementation:

export interface ISimpleValidatorSetup<TModel, K extends keyof TModel> extends IValidatorSetup<TModel, K> {
    getValidation: () => boolean;
}

export class SimpleValidator<TModel, K extends keyof TModel> extends Validator<TModel, K, ISimpleValidatorSetup<TModel, K>> {
    constructor(setup: ISimpleValidatorSetup<TModel, K>) {
        super(setup);
    }

    public async isValidInternal(_value: TModel[K]): Promise<IValidationPropertyResult> {
        const isValid: boolean = this.setup.getValidation();

        return {
            isValid: isValid,
            errors: []
        };
    }
}

Example:

new SimpleValidator({
    getValidation: () => true
});
// -> isValid = true

or

new SimpleValidator({
    getValidation: () => false
});
// -> isValid = false

Credits

Alexey Ripenko, GitHub

License

MIT