change validation

shared/src/validators/compose.validator.ts

@@ -0,0 +1,10 @@
+
+export const ComposeValidators = (...validators: PropertyDecorator[]): () => PropertyDecorator => {
+  return () => {
+    const decorators = [...validators];
+
+    return (target: Object, propertyKey: string | symbol): void => {
+      decorators.forEach((decorator) => decorator(target, propertyKey));
+    };
+  } 
+};

shared/src/validators/entity-id.validator.ts

@@ -0,0 +1,5 @@
+import { IsInt, IsNotEmpty, IsOptional, Min } from 'class-validator';
+import { ComposeValidators } from './compose.validator';
+
+export const EntityID = ComposeValidators(IsOptional(), IsInt(), Min(0));
+export const EntityIDRequired = ComposeValidators(IsNotEmpty(), IsInt(), Min(0));

shared/src/validators/user.validators.ts

@@ -0,0 +1,18 @@
+import { IsAlphanumeric, IsNotEmpty, IsString, Length } from 'class-validator';
+import { ComposeValidators } from './compose.validator';
+
+// Match this with user validators in frontend
+// (Frontend is not security focused, but it tells the user what is wrong)
+
+export const IsUsername = ComposeValidators(
+  IsNotEmpty(),
+  IsString(),
+  Length(4, 32),
+  IsAlphanumeric(),
+);
+
+export const IsPlainTextPwd = ComposeValidators(
+  IsNotEmpty(),
+  IsString(),
+  Length(4, 1024),
+);