plexus-form

A dynamic form component for react using JSON-Schema.

plexus-form

A dynamic form component for React using a specification format based on JSON-Schema.

Demo

The full code for the demo can be found at https://github.com/AppliedMathematicsANU/plexus-form/blob/master/demos/demo.jsx.

Plexus-form takes a JavaScript object describing the shape of the data we want a user to provide - a schema - and automatically creates a form based on that schema. It also validates user inputs by calling a pluggable validator which uses the same schema.

var React    = require('react');
var validate = require('plexus-validate');
var Form     = require('plexus-form');

var schema = {
  title      : "My pretty form",
  description: "Declarative pure data DSLs are the best.",
  type       : "object",
  properties : {
    comment: {
      title      : "Your comment",
      description: "Type something here.",
      type       : "string",
      minLength  : 1
    }
  }
};

var onSubmit = function(data, buttonValue, errors) {
  alert('Data  : '+JSON.stringify(data)+'\n'+
        'Button: '+buttonValue+'\n'+
        'Errors: '+JSON.stringify(errors));
};

React.render(<Form
               schema   = {schema}
               validate = {validate}
               onSubmit = {onSubmit} />,
             document.body);

Plexus-form and plexus-validate take a plain JavaScript data object as input rather than a JSON-formatted string.

The following JSON-Schema properties are supported:

  • description
  • enum
  • enumNames
  • items
  • oneOf
  • properties
  • title
  • type
  • $ref

Additional properties relevant to data validation are implemented by plexus-validate.

JSON-Schema references can only point to elements within the schema object itself. URI references are not supported.

Plexus-form extends the JSON-Schema specification with two new properties x-hints and x-ordering. The latter, x-ordering, specifies a default order for the elements under the current object. The former, x-hints, can be used to annotate a schema with additional hints on how the data is to be handled or displayed. The relevant pieces of information for plexus-form are found under schema["x-hints"].form. We'll explore these extension in more detail in the following sections.

var schema = {
  type      : "object",
  properties: {
    comment: { title: "Comment" },
    email  : { title: "Email" },
    name   : { title: "Name" }
  },
  "x-ordering": ["name", "email", "comment"]
};

Plexus-form assigns the following CSS classes automatically:

  • form-section
  • form-subsection
  • form-section-title
  • form-element

Additional CSS classes can be specified via x-hints like so:

var schema = {
  type      : "object",
  properties: {
    name : {
      title: "Name",
      "x-hints": {
        form: {
          classes: [ "form-text-field", "form-name-field" ]
        }
      }
    },
    email: {
      title: "Email",
      "x-hints": {
        form: {
          classes: [ "form-text-field", "form-email-field" ]
        }
      }
    }
  },
  "x-hints": {
    form: {
      classes: [ "form-person-section" ]
    }
  }
};
var schema = {
  type      : "object",
  properties: {
    contact: {
      title      : "Contact details",
      description: "How would you like to be contacted?",
      type       : "object",
      properties : {
        contactType: {
          title      : "Contact medium",
          description: "Please pick your preferred medium"
        }
      },
      oneOf: [
        {
          properties: {
            contactType: { enum: [ "Email" ] },
            email      : { title: "Email address" }
          }
        },
        {
          properties: {
            contactType: { enum: [ "Telephone" ] },
            phoneNumber: { title: "Telephone number" }
          }
        },
        {
          properties: {
            contactType: { enum: [ "Physical mail" ] },
            address    : { title: "Street address" },
            postcode   : { title: "Post or area code" },
            state      : { title: "State or province" },
            country    : { title: "Country" }
          }
        }
      ],
      "x-hints": { form: { selector: "contactType" } }
    }
  }
};

The following example shows how to associate a user-defined input handler with a data element. The association happens indirectly via a symbolic name and a handler object that assigns functions to names so that the schema itself remains easily serializable. We use a very simplistic file uploader component as a demonstration case. Other useful applications of these technique could be an autocompleting text field or a color picker.

The React component handling a data element (here Uploader) must call this.props.onChange whenever the data has changed. It should delegate low-level key press events it does not handle itself to this.props.onKeyPress, which enables the <Form> component to handle the "Enter" key consistently throughout the form.

var schema = {
  "x-hints" : {
    form: {
      inputComponent: "uploader"
    }
  }
};

var Uploader = React.createClass({
  componentDidMount: function() {
    var input = document.createElement('input');
    input.type = 'file';
    input.multiple = false;
    input.addEventListener('change', this.loadFile);
    this._input = input;
  },

  loadFile: function(event) {
    var files = event.target.files;
    var handleData = this.handleData;
    var file = files[0];
    var reader = new FileReader();

    reader.onload = function(event) {
      handleData(file, event.target.result);
    };

    reader.readAsText(file);
  },

  handleData: function(file, data) {
    this.props.onChange({
      name: file.name,
      type: file.type,
      size: file.size,
      data: data.slice(0, 1000) // truncate data in this demo
    });
  },

  openSelector: function() {
    this._input.click();
  },

  handleKeyPress: function(event) {
    this.props.onKeyPress(event);
  },

  render: function() {
    return (
      <button onClick = { this.openSelector }>
        Select a file
      </button>
    );
  }
});

var onSubmit = function(data, buttonValue, errors) {
  alert('Data  : '+JSON.stringify(data)+'\n'+
        'Button: '+buttonValue+'\n'+
        'Errors: '+JSON.stringify(errors));
};

var handlers = {
  uploader: Uploader
};

React.render(<Form
               buttons  = {[]}
               schema   = {schema}
               validate = {validate}
               onSubmit = {onSubmit}
               handlers = {handlers}
               submitOnChange = {true} />,
             document.body);

License

The MIT License (MIT)

Copyright (c) 2015 The Australian National University

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.