Text input fields

AI-generated Key Takeaways

• A text input field stores both a string value and a string text, where the value is always valid but the text can be any entered string.

• Text input fields can be created using either JSON or JavaScript, with options for setting a default value and disabling spellcheck.

• The value of a text input field is serialized in both JSON and XML formats.

• Spellcheck is enabled by default but can be toggled on or off for individual fields or globally.

• Validators can be used to modify the input text of a text input field before it is stored as the value.

A text input field stores a string as its value and a string as its text. Its value is always a valid string, while its text could be any string entered into its editor.

Text input field

Text input field with editor open

Text input field on collapsed block

Creation

JSON

{
  "type": "example_textinput",
  "message0": "text input: %1",
  "args0": [
    {
      "type": "field_input",
      "name": "FIELDNAME",
      "text": "default text",
      "spellcheck": false
    }
  ]
}

JavaScript

Blockly.Blocks['example_textinput'] = {
  init: function() {
    this.appendDummyInput()
        .appendField("text input:")
        .appendField(new Blockly.FieldTextInput('default text'),
            'FIELDNAME');
  }
};

The text input constructor takes in an optional value and an optional validator. The value should cast to a string. If it is null or undefined, an empty string will be used.

The JSON definition also allows you to set the spellcheck option.

Serialization and XML

JSON

The JSON for a text input field looks like so:

{
  "fields": {
    "FIELDNAME": "text"
  }
}

Where FIELDNAME is a string referencing a text input field, and the value is the value to apply to the field. The value follows the same rules as the constructor value.

XML

The XML for a text input field looks like so:

<field name="FIELDNAME">text</field>

Where the field's name attribute contains a string referencing a text input field, and the inner text is the value to apply to the field. The inner text value follows the same rules as the constructor value.

Customization

Spellcheck

The setSpellcheck function can be used to set whether the field spellchecks its input text or not.

Text input fields with and without spellcheck

Spellchecking is on by default.

This applies to individual fields. If you want to modify all fields change the Blockly.FieldTextInput.prototype.spellcheck_ property.

Creating a text input validator

Note: For information on validators in general see Validators.

A text input field's value is a string, so any validators must accept a string and return a string, null, or undefined.

Here is an example of a validator that removes all a characters from the string:

function(newValue) {
  return newValue.replace(/a/g, '');
}