command-line-callback v2.7.1

command-line-callback

Create git-style command structure that calls functions within your application. Defined commands can also produce help output when the --help flag is used and can accept environment variables and environment files.

Usage Example

index.js

var Command = require('command-line-callback');

// define the command configuration
var configuration = {
    brief: 'Assign a random value to a person.',
    options: {
        fullName: {
            alias: 'f',
            description: "A person's full name.",
            env: 'FULL_NAME',
            type: String,
            validate: function(value) {
                return value.length >= 0;
            },
            required: true
        },
        min: {
            defaultValue: 0,
            description: 'The minimum assignable value.',
            type: Number,
            transform: function(value) {
                return Math.round(value);
            }
        },
        max: {
            alias: 'x',
            description: 'The maximum assignable value.',
            type: Number,
            required: true
        }
    }
};

// define the command callback
function assign(options) {
    var diff = options.max - options.min;
    var value = options.min + (Math.random() * diff);
    console.log(options.fullName + ' assigned value ' + value);
}

// define the command
Command.define('assign', assign, configuration);

// evaluate the command line arguments and call the associated command
Command.evaluate();

Execute the Command from the Command Line

$ node index.js assign --full-name 'Bob Smith' --min 5 -x 10

Optionally, because just one command is defined it will be called if no command is specified.

$ node index.js -f "Bob Smith" --max 10

Get Command Line Help

$ node index.js --help

Quick Links

• Explanation of all configuration settings
• Explanation of options configuration settings
• Full Example with Use Cases

API

defaultCommand

Get or set the name of the default command. If the application is stared from the command line without a command, and multiple commands are defined, then the application will attempt to execute the default command. The default command defaults to default.

Example

var command = require('command-line-callback');
command.defaultCommand = 'foo';
command.define('foo', function(config) { ... }, { ... });
command.define('bar', function(config) { ... }, { ... });
command.evaluate();

config ( commandName , options )

Get a normalized configuration for the specified command. The configuration returned from this function can be passed directly into the callback function that was defined for this command.

• commandName - The name of the command.
• options - An object with key value pairs to pass to the command callback. This object will have it's values validated and transformed, but the values will not go through the type parser.

Returns a normalized and validated configuration object.

define ( commandName, callback , configuration )

Define a git-style command, the function it should call, and the configuration options that link the command line to the callback.

Parameters

• commandName - The name of the command.
• callback - The function to call once the command line arguments have been parsed. This funciton will receive one parameter: an object that represents the values from the command line arguments.
• configuration - The command configuration. Read up on the details of the configuration.

Returns undefined.

evaluate ( args )

Evaluate input arguments to determine which command to run and with what options. The result will be logged to the console.

Parameters

• args - This optional parameter must be an array of strings. If not supplied then it will use the command line arguments used to start the application.

Returns undefined.

execute ( commandName, options )

Execute a defined command from within your code.

Parameters

• commandName - The name of the command.

• options - An object with key value pairs to pass to the command callback. This object will have it's values validated and transformed, but the values will not go through the type parser.

Returns whatever the command returns.

getCommandUsage ( commandName )

Get the help string for the command specified.

Parameters

• commandName - The name of the command. If omitted then usage for all commands will be returned.

Returns a string with the command's help.

list ( )

Get the names of all defined commands.

Returns a string with the command's help.

parser

The parser is the tool that is used to convert string values into primitives or objects. This tool is uses by the command line args tool to convert strings from the command line into usable values.

parser.define ( factory, emptyReplacement , parser )

Define a parser that converts the a string into its value equivalent.

Parameters

• factory - The function that will take parameters to make an instance.
• emptyReplacement - If the value is an empty string, this string value will be used to replace the empty string prior to conversion.
• parser - A function that parses the string value before calling the factory to create the instance. If this parameter is omitted then the factory will be called with the string value as its only parameter.

Returns undefined.

Example

var command = require('command-line-callback');
command.parser.define(Boolean, 'true', function(value, factory) {
    // Note: factory === Boolean
    if (value === 'true') return factory(true);
    if (value === 'false') return factory(false);
    if (!isNaN(value)) return factory(parseInt(value));
    return factory(!!value);
});

parser.exists ( factory )

Check if the parser has been defined.

Parameters

• factory - The function that will take parameters to make an instance.

Returns a boolean.

parser.parse ( factory, value )

Parse and string value and get back its instance value.

Parameters

• factory - The function that will take parameters to make an instance.
• value - A string value to parse.

Returns the value that the factory produces.

Example

var value = command.parser.parse(Boolean, '');  // true