fix: add validation backend check

adminforth/documentation/docs/tutorial/03-Customization/13-standardPagesTuning.md

@@ -343,7 +343,32 @@ export default {
 
 ### Validation
 
-[Documentation in progress]
+In cases when column values must follow certain format, you can add `validation` to it.
+`validation` is an array of rules, each containing `regExp` that defines a format for a value and `message` that will be displayed in case when entered value does not pass the check.
+
+```typescript title="./resources/users.ts"
+export default {
+      name: 'users',
+      columns: [
+        ...
+        {
+          name: 'email',
+          required: true,
+          isUnique: true,
+          validation: [
+            {
+              regExp: '^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}$',
+              message: 'Email is not valid, must be in format [email protected]',
+            },
+          ],
+        },
+      ],
+    },
+    ...
+  ],
+```
+
+> `validation` checks are enforced both on frontend and backend.
 
 ### Foreign resources
 

adminforth/index.ts

@@ -53,6 +53,36 @@ class AdminForth implements IAdminForth {
       return await AdminForthAuth.generatePasswordHash(password);
     },
 
+    applyRegexValidation(value, validation) {
+      if (validation?.length) {
+        const validationArray = validation;
+        for (let i = 0; i < validationArray.length; i++) {
+          if (validationArray[i].regExp) {
+            let flags = '';
+            if (validationArray[i].caseSensitive) {
+              flags += 'i';
+            }
+            if (validationArray[i].multiline) {
+              flags += 'm';
+            }
+            if (validationArray[i].global) {
+              flags += 'g';
+            }
+
+            const regExp = new RegExp(validationArray[i].regExp, flags);
+            if (value === undefined || value === null) {
+              value = '';
+            }
+            let valueS = `${value}`;
+
+            if (!regExp.test(valueS)) {
+              return validationArray[i].message;
+            }
+          }
+        }
+      }
+    },
+
     PASSWORD_VALIDATORS: {
       UP_LOW_NUM_SPECIAL: {
         regExp: '^(?=.*[A-Z])(?=.*[a-z])(?=.*[0-9])(?=.*[!@#\\$%\\^&\\*\\(\\)\\-_=\\+\\[\\]\\{\\}\\|;:\',\\.<>\\/\\?]).+$',
@@ -320,6 +350,14 @@ class AdminForth implements IAdminForth {
     { resource: AdminForthResource, record: any, adminUser: AdminUser, extra?: HttpExtra }
   ): Promise<{ error?: string, createdRecord?: any }> {
 
+    // check if record with validation is valid
+    for (const column of resource.columns.filter((col) => col.name in record && col.validation)) {
+      const error = AdminForth.Utils.applyRegexValidation(record[column.name], column.validation);
+      if (error) {
+        return { error };
+      }
+    }
+
     // check if record with minValue or maxValue is within limits
     for (const column of resource.columns.filter((col) => col.name in record
       && ['integer', 'decimal', 'float'].includes(col.type)
@@ -397,6 +435,14 @@ class AdminForth implements IAdminForth {
     { resource: AdminForthResource, recordId: any, record: any, oldRecord: any, adminUser: AdminUser, extra?: HttpExtra }
   ): Promise<{ error?: string }> {
 
+    // check if record with validation is valid
+    for (const column of resource.columns.filter((col) => col.name in record && col.validation)) {
+      const error = AdminForth.Utils.applyRegexValidation(record[column.name], column.validation);
+      if (error) {
+        return { error };
+      }
+    }
+
     // check if record with minValue or maxValue is within limits
     for (const column of resource.columns.filter((col) => col.name in record
       && ['integer', 'decimal', 'float'].includes(col.type)