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Using the canExecute Command Hook

This article will guide you through how to prevent a custom command from executing through the canExecute hook.


Create an App with an IWTM and a Custom Component#

First, let's create an app with an IWTM and a custom component that implements a simple command that displays an alert.

<?xml version="1.0" encoding="UTF-8"?><layout xmlns="" xmlns:custom="custom.abc123">    <map>        <iwtm config="iwtm-config" slot="top-left" />        <custom:custom-component margin="3" slot="top-center"/>    </map></layout>

Add a Button to Toggle the canExecute Status#

Next, let's add a button to the custom component that will toggle the canExecute status of the custom.command-with-can-execute command.

import {    LayoutElement,    LayoutElementProperties,} from "@vertigis/web/components";import Button from "@vertigis/web/ui/Button";import React from "react";
import CustomModel from "./CustomModel";
const CustomComponent = (    props: LayoutElementProperties<CustomModel>) => {    const { model } = props;
    return (        <LayoutElement {...props}>            <Button onClick={() => model.toggleCanExecute()}>                Toggle Can Execute            </Button>        </LayoutElement>    );};
export default CustomComponent;

Implement the canExecute Function#

Finally, we need to implement the canExecute method for the custom.command-with-can-execute command. This method should be decorated with @canExecute and return a boolean indicating whether the command can execute.


If the command takes an argument, the @canExecute method will also be passed that argument.

import {    ComponentModelBase,    serializable,} from "@vertigis/web/models";import { command, canExecute } from "@vertigis/web/messaging";
@serializableexport default class CustomModel extends ComponentModelBase {    private _canExecuteValue: boolean = false;
    @command("custom.command-with-can-execute")    protected _commandWithCanExecute(): void {        this.messages.commands.ui.alert.execute({            message: "Executed `custom.command-with-can-execute`",        });    }
    @canExecute("custom.command-with-can-execute")    protected _canExecuteImplementation_(): boolean {        return this._canExecuteValue;    }
    toggleCanExecute(): void {        this._canExecuteValue = !this._canExecuteValue;        this.messages            .command("custom.command-with-can-execute")            .canExecuteChanged.publish();    }}

Live Sample#

Check out a live SDK sample of a command that has a canExecute hook.

Next Steps#

Commands and Operations in Services

Learn more about commands and operations in services

Custom Services

Learn more about custom services