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AJSF (Angular JSON Schema Form)

N.B: For Angular6-json-schema-form please check this documentation.

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Note: This project is a continuation to dschnelldavis/Angular2-json-schema-form and is not affiliated with any organization.

A JSON Schema Form builder for Angular, similar to, and mostly API compatible with:


Check out the live demo and play with the examples

Check out some examples here.

This example playground features over 70 different JSON Schemas for you to try (including all examples used by each of the three libraries listed above), and the ability to quickly view any example formatted with Material Design, Bootstrap 3, Bootstrap 4, or without any formatting.


To install from NPM/YARN and use in your own project

If you want to try out the libraries, you can for example install @ajsf/material package from NPM which uses material-angular UI. You can use either NPM or Yarn. To install with NPM, run the following from your terminal:

npm install @ajsf/material@latest

With YARN, run the following:

yarn add @ajsf/material@latest

Then import MaterialDesignFrameworkModule in your main application module like this:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { MaterialDesignFrameworkModule } from '@ajsf/material';

import { AppComponent } from './app.component';

  declarations: [ AppComponent ],
  imports: [
  providers: [],
  bootstrap: [ AppComponent ]
export class AppModule { }

Four framework modules are currently included, the import is the same as above :

  • MaterialDesignFrameworkModule from @ajsf/material — Material Design
  • Bootstrap3FrameworkModule from @ajsf/bootstrap3 — Bootstrap 3
  • Bootstrap4FrameworkModule from @ajsf/bootstrap4 — Bootstrap 4
  • JsonSchemaFormModule from @ajsf/core — plain HTML (for testing)

It is also possible to load multiple frameworks and switch between them at runtime, like the example playground on GitHub. But most typical sites will just load one framework.

To install from GitHub

To install the library and the example playground from GitHub, clone https://github.com/hamzahamidi/ajsf.git with your favorite git program. Or, assuming you have git and Node/YARN installed, enter the following in your terminal:

git clone https://github.com/hamzahamidi/ajsf.git ajsf
cd ajsf
yarn install
yarn start

This should start a server with the example playground, which you can view in your browser at http://localhost:4200

The source code is composed as the following:

  • projects/ajsf-core - Angular JSON Schema Form main library
  • projects/ajsf-bootstrap3 - Framework for Bootstrap 3
  • projects/ajsf-bootstrap4 - Framework for Bootstrap 4
  • projects/ajsf-material - Framework for Angular Material
  • projects/ajsf-core/src/lib/framework-library - framework library
  • projects/ajsf-core/src/lib/widget-library - widget library
  • projects/ajsf-core/src/lib/shared - various utilities and helper functions
  • demo - the demonstration playground example application
  • demo/assets/example-schemas - JSON Schema examples used in the playground

If you want detailed documentation describing the individual functions used in this library, check the README in each component. (Angular JSON Schema Form is still a work in progress, so right now this documentation varies from highly detailed to completely missing.)

Using Angular JSON Schema Form

Basic use

For basic use, after loading JsonSchemaFormModule as described above, to display a form in your Angular component, simply add the following to your component's template:


Where schema is a valid JSON schema object, and onSubmit calls a function to process the submitted JSON form data. If you don't already have your own schemas, you can find a bunch of samples to test with in the demo/assets/example-schemas folder, as described above.

framework is for the template you want to use, the default value is no-framwork. The possible values are:

  • material-design for Material Design.
  • bootstrap-3 for Bootstrap 3.
  • bootstrap-4 for 'Bootstrap 4.
  • no-framework for (plain HTML).

Setting loadExternalAssets="true" will automatically load any additional assets needed by the display framework. It is useful when you are trying out this library, but production sites should instead load all required assets separately. For full details see 'Changing or adding frameworks', below.

Data-only mode

Angular JSON Schema Form can also create a form entirely from a JSON object—with no schema—like so:

exampleJsonObject = {
  "first_name": "Jane", "last_name": "Doe", "age": 25, "is_company": false,
  "address": {
    "street_1": "123 Main St.", "street_2": null,
    "city": "Las Vegas", "state": "NV", "zip_code": "89123"
  "phone_numbers": [
    { "number": "702-123-4567", "type": "cell" },
    { "number": "702-987-6543", "type": "work" }
  ], "notes": ""

In this mode, Angular JSON Schema Form automatically generates a schema from your data. The generated schema is relatively simple, compared to what you could create on your own. However, as the above example shows, it does detect and enforce string, number, and boolean values (nulls are also assumed to be strings), and automatically allows array elements to be added, removed, and reordered.

After displaying a form in this mode, you can also use the formSchema and formLayout outputs (described in 'Debugging inputs and outputs', below), to return the generated schema and layout, which will give you a head start on writing your own schemas and layouts by showing you examples created from your own data.

Also, notice that the 'ngModel' input supports Angular's 2-way data binding, just like other form controls, which is why it is not always necessary to use an onSubmit function.

Advanced use

Additional inputs an outputs

For more control over your form, you may provide these additional inputs:

  • layout array with a custom form layout (see Angular Schema Form's form definitions for information about how to construct a form layout)
  • data object to populate the form with default or previously submitted values
  • options object to set any global options for the form
  • widgets object to add custom widgets
  • language string to set the error message language (currently supports 'de', 'en', 'es', 'fr', 'it', 'pt', 'zh')
  • framework string or object to set which framework to use

For framework, you can pass in your own custom framework object, or, if you've loaded multiple frameworks, you can specify the name of the framework you want to use. To switch between the included frameworks, use 'material-design', 'bootstrap-3', 'bootstrap-4', and 'no-framework'.

If you want more detailed output, you may provide additional functions for onChanges to read the values in real time as the form is being filled out, and you may implement your own custom validation indicators from the boolean isValid or the detailed validationErrors outputs.

Here is an example:


Note: If you prefer brackets around all your attributes, the following is functionally equivalent:


If you use this syntax, make sure to include the nested quotes ("' and '") around the language and framework names. (If you leave out the inner quotes, Angular will read them as a variable names, rather than strings, which will cause errors. All un-bracketed attributes, however, are automatically read as strings, so they don't need inner quotes.)

Single-input mode

You may also combine all your inputs into one compound object and include it as a form input, like so:

const yourCompoundInputObject = {
  schema:    { ... },  // REQUIRED
  layout:    [ ... ],  // optional
  data:      { ... },  // optional
  options:   { ... },  // optional
  widgets:   { ... },  // optional
  language:   '...' ,  // optional
  framework:  '...'    // (or { ... }) optional

You can also mix these two styles depending on your needs. In the example playground, all examples use the combined form input for schema, layout, and data, which enables each example to control those three inputs, but the playground uses separate inputs for language and framework, enabling it to change those settings independent of the example.

Combining inputs is useful if you have many unique forms and store each form's data and schema together. If you have one form (or many identical forms), it will likely be more useful to use separate inputs for your data and schema. Though even in that case, if you use a custom layout, you could store your schema and layout together and use one input for both.

Compatibility modes

If you have previously used another JSON form creation library—Angular Schema Form (for AngularJS), React JSON Schema Form, or JSON Form (for jQuery)—in order to make the transition easier, Angular JSON Schema Form will recognize the input names and custom input objects used by those libraries. It should automatically work with JSON Schemas in version 6, version 4, version 3, or the truncated version 3 format supported by JSON Form. So the following will all work:

Angular Schema Form (AngularJS) compatibility:


React JSON Schema Form compatibility:


JSON Form (jQuery) compatibility:

    schema: yourJsonSchema,
    form: yourJsonFormLayout,
    customFormItems: yourJsonFormCustomFormItems,
    value: yourData

Note: 2-way data binding will work with any dedicated data input, including 'data', 'model', 'ngModel', or 'formData'. However, 2-way binding will not work with the combined 'form' input.

Debugging inputs and outputs

Finally, Angular JSON Schema Form includes some additional inputs and outputs for debugging:

  • debug input — Activates debugging mode.
  • loadExternalAssets input — Causes external JavaScript and CSS needed by the selected framework to be automatically loaded from a CDN (this is not 100% reliable, so while this can be helpful during development and testing, it is not recommended for production)—Note: If you are using this mode and get a console error saying an external asset has not loaded (such as jQuery, required for Bootstrap 3) simply reloading your web browser will usually fix it.
  • formSchema and formLayout outputs — Returns the final schema and layout used to create the form (which will either show how your original input schema and layout were modified, if you provided inputs, or show you the automatically generated ones, if you didn't).


In addition to a large number of user-settable options, Angular JSON Schema Form also has the ability to load custom form control widgets and layout frameworks. All forms are constructed from these basic components. The default widget library includes all standard HTML 5 form controls, as well as several common layout patterns, such as multiple checkboxes and tab sets. The default framework library includes templates to style forms using Material Design, Bootstrap 3, or Bootstrap 4 (or plain HTML with no formatting, which is not useful in production, but can be helpful for development and debugging).

User settings

(TODO: List all available user settings, and configuration options for each.)

Creating custom input validation error messages

You can easily add your own custom input validation error messages, either for individual control widgets, or for your entire form.

Setting error messages for individual controls or the entire form

To set messages for individual form controls, add them to that control's node in the form layout, like this:

const yourFormLayout = [
  { key: 'name',
    title: 'Enter your name',
    validationMessages: {
      // Put your error messages for the 'name' field here
  { type: 'submit', title: 'Submit' }

To set messages for the entire form, add them to the form options, inside the defautWidgetOptions validationMessages object, like this:

const yourFormOptions = {
  defautWidgetOptions: {
    validationMessages: {
      // Put your error messages for the entire form here

How to format error messages

The validationMessages object—in either a layout node or the form options—contains the names of each error message you want to set as keys, and the corresponding messages as values. Messages may be in any of the following formats:

  • String: A plain text message, which is always the same.
  • String template: A text message that includes Angular template-style {{variables}}, which will be be replaced with values from the returned error object.
  • Function: A JavaScript function which accepts the error object as input, and returns a string error message.

Here are examples of all three error message types:

validationMessages: {

  // String error message
  required: 'This field is required.',

  // String template error message
  // - minimumLength variable will be replaced
  minLength: 'Must be at least {{minimumLength}} characters long.',

  // Function error message
  // - example error object:   { multipleOfValue: 0.01, currentValue: 3.456 }
  // - resulting error message: 'Must have 2 or fewer decimal places.'
  multipleOf: function(error) {
    if ((1 / error.multipleOfValue) % 10 === 0) {
      const decimals = Math.log10(1 / error.multipleOfValue);
      return `Must have ${decimals} or fewer decimal places.`;
    } else {
      return `Must be a multiple of ${error.multipleOfValue}.`;

(Note: These examples are from the default set of built-in error messages, which includes messages for all JSON Schema errors except type, const, enum, and dependencies.)

Available input validation errors and object values

Here is a list of all the built-in JSON Schema errors, which data type each error is available for, and the values in their returned error objects:

Error name Data type Returned error object values
required any (none)
type any requiredType, currentValue
const any requiredValue, currentValue
enum any allowedValues, currentValue
minLength string minimumLength, currentLength
maxLength string maximumLength, currentLength
pattern string requiredPattern, currentValue
format string requiredFormat, currentValue
minimum number minimumValue, currentValue
exclusiveMinimum number exclusiveMinimumValue, currentValue
maximum number maximumValue, currentValue
exclusiveMaximum number exclusiveMaximumValue, currentValue
multipleOf number multipleOfValue, currentValue
minProperties object minimumProperties, currentProperties
maxProperties object maximumProperties, currentProperties
dependencies * object (varies, based on dependencies schema)
minItems array minimumItems, currentItems
maxItems array maximumItems, currentItems
uniqueItems array duplicateItems
contains * array requiredItem
  • Note: The contains and dependencies validators are still in development, and do not yet work correctly.

Changing or adding widgets

To add a new widget or override an existing widget, either add an object containing your new widgets to the widgets input of the <json-schema-form> tag, or load the WidgetLibraryService and call registerWidget(widgetType, widgetComponent), with a string type name and an Angular component to be used whenever a form needs that widget type.


import { YourInputWidgetComponent } from './your-input-widget.component';
import { YourCustomWidgetComponent } from './your-custom-widget.component';
const yourNewWidgets = {
  input: YourInputWidgetComponent,          // Replace existing 'input' widget
  custom-control: YourCustomWidgetComponent // Add new 'custom-control' widget




import { WidgetLibraryService } from '@ajsf/core';
constructor(private widgetLibrary: WidgetLibraryService) { }
// Replace existing 'input' widget:
widgetLibrary.registerWidget('input', YourInputWidgetComponent);
// Add new 'custom-control' widget:
widgetLibrary.registerWidget('custom-control', YourCustomWidgetComponent);

To see many examples of widgets, explore the source code, or call getAllWidgets() from the WidgetLibraryService to see all widgets currently available in the library. All default widget components are in the projects/json-schema-form/src/lib/widget-library folder, and all custom Material Design widget components are in the projects/json-schema-form/src/lib/framework-library/material-design-framework folder. (The Bootstrap 3 and Bootstrap 4 frameworks just reformat the default widgets, and so do not include any custom widgets of their own.)

Changing or adding frameworks

To change the active framework, either use the framework input of the <json-schema-form> tag, or load the FrameworkLibraryService and call setFramework(yourCustomFramework), with either the name of an available framework ('bootstrap-3', 'bootstrap-4', 'material-design', or 'no-framework'), or with your own custom framework object, like so:

import { YourFrameworkComponent } from './your-framework.component';
import { YourWidgetComponent } from './your-widget.component';
const yourCustomFramework = {
  framework: YourFrameworkComponent,                                // required
  widgets:     { 'your-widget-name': YourWidgetComponent,   ... },  // optional
  stylesheets: [ '//url-to-framework-external-style-sheet', ... ],  // optional
  scripts:     [ '//url-to-framework-external-script',      ... ]   // optional




import { FrameworkLibraryService } from '@ajsf/core';
constructor(private frameworkLibrary: FrameworkLibraryService) { }

The value of the required framework key is an Angular component which will be called to format each widget before it is displayed. The optional widgets object contains any custom widgets, which will override or supplement the built-in widgets. And the optional stylesheets and scripts arrays contain URLs to any additional external style sheets or JavaScript libraries required by the framework. These are the external stylesheets and scripts that will be loaded if the "loadExternalAssets" option is set to "true".

Loading external assets required by a framework

Most Web layout framework libraries (including both Bootstrap and Material Design) need additional external JavaScript and/or CSS assets loaded in order to work properly. The best practice is to load these assets separately in your site, before calling Angular JSON Schema Form. (For the included libraries, follow these links for more information about how to do this: Bootstrap and Material Design.)

Alternately, during development, you may find it helpful to let Angular JSON Schema Form load these resources for you (as wed did in the 'Basic use' example, above), which you can do in several ways:

  • Call setFramework with a second parameter of true (e.g. setFramework('material-design', true)), or
  • Add loadExternalAssets: true to your options object, or
  • Add loadExternalAssets="true" to your <json-schema-form> tag, as shown above

Finally, if you want to see what scripts a particular framework will automatically load, after setting that framework you can call getFrameworkStylesheets() or getFrameworkScritps() from the FrameworkLibraryService to return the built-in arrays of URLs.

However, if you are creating a production site you should load these assets separately, and make sure to remove all references to loadExternalAssets to prevent the assets from being loaded twice.

contributing guide

If you like this project and want to contribute you can check this documentation.



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