diff --git a/docs/features/software-templates/writing-custom-field-extensions.md b/docs/features/software-templates/writing-custom-field-extensions.md
index 1d28bd5db9..be00453795 100644
--- a/docs/features/software-templates/writing-custom-field-extensions.md
+++ b/docs/features/software-templates/writing-custom-field-extensions.md
@@ -23,18 +23,19 @@ the `Scaffolder` frontend plugin in your own `App.tsx`.
You can create your own Field Extension by using the
[`createScaffolderFieldExtension`](https://backstage.io/docs/reference/plugin-scaffolder.createscaffolderfieldextension)
-`API` like below:
+`API` like below.
+
+As an example, we will create a component that validates whether a string is in the `Kebab-case` pattern:
```tsx
-//packages/app/src/scaffolder/MyCustomExtension/MyCustomExtension.tsx
+//packages/app/src/scaffolder/ValidateKebabCase/ValidateKebabCaseExtension.tsx
import React from 'react';
import { FieldProps, FieldValidation } from '@rjsf/core';
import FormControl from '@material-ui/core/FormControl';
-import { KubernetesValidatorFunctions } from '@backstage/catalog-model';
/*
This is the actual component that will get rendered in the form
*/
-export const MyCustomExtension = ({
+export const ValidateKebabCaseExtension = ({
onChange,
rawErrors,
required,
@@ -45,8 +46,17 @@ export const MyCustomExtension = ({
margin="normal"
required={required}
error={rawErrors?.length > 0 && !formData}
- onChange={onChange}
- />
+ >
+ Name
+ onChange(e.target?.value)}
+ />
+
+ Use only letters, numbers, hyphens and underscores
+
+
);
};
@@ -55,20 +65,22 @@ export const MyCustomExtension = ({
You will get the value from the `onChange` handler before as the value here to make sure that the types are aligned\
*/
-export const myCustomValidation = (
+export const validateKebabCaseValidation = (
value: string,
validation: FieldValidation,
) => {
- if (!KubernetesValidatorFunctions.isValidObjectName(value)) {
+ const kebabCase = /^[a-z0-9-_]+$/g.test(value);
+
+ if (kebabCase === false) {
validation.addError(
- 'must start and end with an alphanumeric character, and contain only alphanumeric characters, hyphens, underscores, and periods. Maximum length is 63 characters.',
+ `Only use letters, numbers, hyphen ("-") and underscore ("_").`,
);
}
};
```
```tsx
-// packages/app/src/scaffolder/MyCustomExtension/extensions.ts
+// packages/app/src/scaffolder/ValidateKebabCase/extensions.ts
/*
This is where the magic happens and creates the custom field extension.
@@ -81,21 +93,24 @@ import {
scaffolderPlugin,
createScaffolderFieldExtension,
} from '@backstage/plugin-scaffolder';
-import { MyCustomExtension, myCustomValidation } from './MyCustomExtension';
+import {
+ ValidateKebabCase,
+ validateKebabCaseValidation,
+} from './ValidateKebabCase';
-export const MyCustomFieldExtension = scaffolderPlugin.provide(
+export const ValidateKebabCaseFieldExtension = scaffolderPlugin.provide(
createScaffolderFieldExtension({
- name: 'MyCustomExtension',
- component: MyCustomExtension,
- validation: myCustomValidation,
+ name: 'ValidateKebabCase',
+ component: ValidateKebabCase,
+ validation: validateKebabCaseValidation,
}),
);
```
```tsx
-// packages/app/src/scaffolder/MyCustomExtension/index.ts
+// packages/app/src/scaffolder/ValidateKebabCase/index.ts
-export { MyCustomFieldExtension } from './extensions';
+export { ValidateKebabCaseFieldExtension } from './extensions';
```
Once all these files are in place, you then need to provide your custom
@@ -117,7 +132,7 @@ const routes = (
Should look something like this instead:
```tsx
-import { MyCustomFieldExtension } from './scaffolder/MyCustomExtension';
+import { ValidateKebabCaseFieldExtension } from './scaffolder/ValidateKebabCase';
import { ScaffolderFieldExtensions } from '@backstage/plugin-scaffolder';
const routes = (
@@ -125,7 +140,7 @@ const routes = (
...
}>
-
+
...
@@ -158,7 +173,9 @@ spec:
title: Name
type: string
description: My custom name for the component
- ui:field: MyCustomExtension
+ ui:field: ValidateKebabCaseExtension
+ steps:
+ [...]
```
## Access Data from other Fields