FRONTEND-8638 :: Feature :: Add Custom Angular Validation Patterns

packages/angular/src/form-validation/form-validators.ts

@@ -0,0 +1,45 @@
+import { AbstractControl, ValidationErrors, ValidatorFn } from '@angular/forms';
+
+export class FormValidators {
+    private static readonly ERROR_BODY = { valid: false };
+
+    /**
+     * Substitution of the native `Validations.pattern` that allows
+     * an id as an input so multiple patterns can be used and identified.
+     * It also allows a string pattern or a RegExp.
+     */
+    private static pattern(pattern: RegExp | string, id = 'pattern'): ValidatorFn {
+        return (control: AbstractControl): ValidationErrors | null => {
+            return FormValidators.isPatternFound(control, pattern)
+                ? null
+                : {
+                      [id]: FormValidators.ERROR_BODY,
+                  };
+        };
+    }
+
+    /**
+     * Unlike "pattern" validator, "errorPattern" uses the pattern
+     * to identify the errors in the FormControl value.
+     */
+    private static errorPattern(pattern: RegExp | string, id = 'errorPattern'): ValidatorFn {
+        return (control: AbstractControl): ValidationErrors | null => {
+            return FormValidators.isPatternFound(control, pattern)
+                ? {
+                      [id]: FormValidators.ERROR_BODY,
+                  }
+                : null;
+        };
+    }
+
+    private static isPatternFound(control: AbstractControl, pattern: RegExp | string): boolean {
+        const value = control.value;
+        if (!value) {
+            return false;
+        }
+
+        const regex = typeof pattern === 'string' ? new RegExp(pattern) : pattern;
+
+        return regex.test(value);
+    }
+}