mobx-utils/lib/create-view-model.d.ts

Utility functions and common patterns for MobX

import { ObservableMap, IComputedValue } from "mobx";
export interface IViewModel<T> {
    model: T;
    reset(): void;
    submit(): void;
    isDirty: boolean;
    changedValues: Map<keyof T, T[keyof T]>;
    isPropertyDirty(key: keyof T): boolean;
    resetProperty(key: keyof T): void;
}
export declare class ViewModel<T> implements IViewModel<T> {
    model: T;
    localValues: ObservableMap<keyof T, T[keyof T]>;
    localComputedValues: ObservableMap<keyof T, IComputedValue<T[keyof T]>>;
    get isDirty(): boolean;
    get changedValues(): Map<keyof T, T[keyof T]>;
    constructor(model: T);
    isPropertyDirty: (key: keyof T) => boolean;
    submit(): void;
    reset(): void;
    resetProperty(key: keyof T): void;
}
/**
 * `createViewModel` takes an object with observable properties (model)
 * and wraps a viewmodel around it. The viewmodel proxies all enumerable properties of the original model with the following behavior:
 *  - as long as no new value has been assigned to the viewmodel property, the original property will be returned.
 *  - any future change in the model will be visible in the viewmodel as well unless the viewmodel property was dirty at the time of the attempted change.
 *  - once a new value has been assigned to a property of the viewmodel, that value will be returned during a read of that property in the future. However, the original model remain untouched until `submit()` is called.
 *
 * The viewmodel exposes the following additional methods, besides all the enumerable properties of the model:
 * - `submit()`: copies all the values of the viewmodel to the model and resets the state
 * - `reset()`: resets the state of the viewmodel, abandoning all local modifications
 * - `resetProperty(propName)`: resets the specified property of the viewmodel
 * - `isDirty`: observable property indicating if the viewModel contains any modifications
 * - `isPropertyDirty(propName)`: returns true if the specified property is dirty
 * - `changedValues`: returns a key / value map with the properties that have been changed in the model so far
 * - `model`: The original model object for which this viewModel was created
 *
 * You may use observable arrays, maps and objects with `createViewModel` but keep in mind to assign fresh instances of those to the viewmodel's properties, otherwise you would end up modifying the properties of the original model.
 * Note that if you read a non-dirty property, viewmodel only proxies the read to the model. You therefore need to assign a fresh instance not only the first time you make the assignment but also after calling `reset()` or `submit()`.
 *
 * @example
 * class Todo {
 *   \@observable title = "Test"
 * }
 *
 * const model = new Todo()
 * const viewModel = createViewModel(model);
 *
 * autorun(() => console.log(viewModel.model.title, ",", viewModel.title))
 * // prints "Test, Test"
 * model.title = "Get coffee"
 * // prints "Get coffee, Get coffee", viewModel just proxies to model
 * viewModel.title = "Get tea"
 * // prints "Get coffee, Get tea", viewModel's title is now dirty, and the local value will be printed
 * viewModel.submit()
 * // prints "Get tea, Get tea", changes submitted from the viewModel to the model, viewModel is proxying again
 * viewModel.title = "Get cookie"
 * // prints "Get tea, Get cookie" // viewModel has diverged again
 * viewModel.reset()
 * // prints "Get tea, Get tea", changes of the viewModel have been abandoned
 *
 * @param {T} model
 * @returns {(T & IViewModel<T>)}
 * ```
 */
export declare function createViewModel<T>(model: T): T & IViewModel<T>;