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Comment: Made some additional minor changes

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To explain what occurs in the the the index.js file, we will break the file down piece by piece.

  1. Describe the node, name, description, category, and icon:

    Code Block
    .add('encodeuri', {
            name: 'Encode URI',
            icon: 'icon.svg',
            description: 'URI encoder.',
            category: 'utils'
    })

    The name is the text that is displayed in the Flow Editor. The default icon is a placeholder (a star) that should be replaced with a graphic that represents the action of the node. The icon is displayed at 28 pixels x 28 pixels. The category is the section in the Flow Editor tool panel where the node is contained.

  2. Add a method to the node and describe its parameters:

    Code Block
    .method('encode', {
            name: 'Encode URI',
            description: 'Encodes a URI by replacing each instance of certain characters with UTF-8 encodings.'
        })
        .parameter('uri', {
            description: 'The URI to encode.',
            type: 'string'
    })

    A method called encode, that is displayed in the Flow Editor as Encode URI, was added. The encode method has a single parameter. If there was more than one parameter, we would repeat the .parameter(name, schema) block. The second value in the parameter method is a JSON Schema that describes the parameter type.

  3. Describe the possible outputs from the method:

    Code Block
    .output('next', {
        name: 'Next',
        description: 'The URI was encoded successfully.',
        context: '$.encodedURI',
        schema: {
            type: 'string'
        }
    })

    The outputs section defines what the possible outcomes of the node are. In this simple case there is just one output; however, however nodes can have multiple outputs with different return types. For example, this node could have added an error output to indicate that encoding failed.

  4. Define the implementation:

    Code Block
    .action(action);

    The action() expects a function that will be passed the request details parameter and a callback object parameter.

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To simplify management of the code, the starter project puts the implementation of the methods in the action.js file. There is not a requirement to follow this pattern, you can structure your project however how best suits your needs.

Code Block
exports = module.exports = function (req, cb) {
        const uri = req.params.uri;
        if (!uri) {
                return cb('invalid argument');
        }
        cb.next(null, encodeURI(uri));
};

This is a simple scenario, but it highlights the main features. The parameters for the node method are accessed under the req.params parameter. In this example, the parameter for the encode method is defined as uri:

Code Block
    .parameter('uri', {
        description: 'The URI to encode.',
        type: 'string'
    })

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These errors are not handled and will abort the flow execution. In general, avoid doing this for any expected error scenarios. If there are known error situations, it is better to define an output for those scenarios and allow the flow designer the flexibility to specify what to do on when an error occurs.

If uri is set, the fallback for the next output is fired. The name of this callback will match the name of the output defined in the method. For example, if you defined an output encoderError, then there would be a callback cb.encoderError(). The encoded string is passed to the callback as the methods output value.

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