diff --git a/Tests.http b/Tests.http
new file mode 100644
index 0000000..e69de29
diff --git a/src/main/java/de/szut/webshop/controller/SupplierController.java b/src/main/java/de/szut/webshop/controller/SupplierController.java
index c0a6585..952019d 100644
--- a/src/main/java/de/szut/webshop/controller/SupplierController.java
+++ b/src/main/java/de/szut/webshop/controller/SupplierController.java
@@ -1,6 +1,8 @@
 package de.szut.webshop.controller;
 
 import de.szut.webshop.dto.AddSupplierDto;
+import de.szut.webshop.model.ContactEntity;
+import de.szut.webshop.model.SupplierEntity;
 import de.szut.webshop.service.SupplierService;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
@@ -18,7 +20,19 @@ public class SupplierController {
 
     @PostMapping
     public String createSupplier(@RequestBody AddSupplierDto dto) {
-        supplierService.createSupplier(dto);
+        SupplierEntity supplier = new SupplierEntity();
+        ContactEntity contact = new ContactEntity();
+
+        contact.setCity(dto.getCity());
+        contact.setPostcode(dto.getPostcode());
+        contact.setStreet(dto.getStreet());
+        contact.setPhone(dto.getPhone());
+
+        supplier.setName(dto.getName());
+        supplier.setContact(contact);
+
+        supplierService.createSupplier(supplier);
+
         return "Supplier created";
     }
 }
diff --git a/src/main/java/de/szut/webshop/model/ArticleEntity.java b/src/main/java/de/szut/webshop/model/ArticleEntity.java
index 0cea4cc..45fe9c7 100644
--- a/src/main/java/de/szut/webshop/model/ArticleEntity.java
+++ b/src/main/java/de/szut/webshop/model/ArticleEntity.java
@@ -1,6 +1,8 @@
 package de.szut.webshop.model;
 
 import jakarta.persistence.*;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.NotNull;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
 import lombok.Setter;
@@ -15,14 +17,16 @@ import java.time.LocalDateTime;
 public class ArticleEntity {
 
     @Id
-    @GeneratedValue
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
+    @NotBlank(message = "Designation is mandatory")
     private String designation;
 
+    @NotNull
     private double price;
 
-    @Column(name = "name", nullable = false)
+    @Column(name = "created_at", nullable = false)
     private LocalDateTime createdAt = LocalDateTime.now();
 
     @Column(name = "updated_at", nullable = false)
diff --git a/src/main/java/de/szut/webshop/model/ContactEntity.java b/src/main/java/de/szut/webshop/model/ContactEntity.java
index b399585..c36161c 100644
--- a/src/main/java/de/szut/webshop/model/ContactEntity.java
+++ b/src/main/java/de/szut/webshop/model/ContactEntity.java
@@ -2,6 +2,8 @@ package de.szut.webshop.model;
 
 
 import jakarta.persistence.*;
+import jakarta.validation.constraints.NotBlank;
+import jakarta.validation.constraints.Size;
 import lombok.Data;
 
 @Data
@@ -12,15 +14,21 @@ public class ContactEntity {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long cid;
 
+    @NotBlank(message = "Street is mandatory")
+    @Size(max = 50, message = "Street must not exceed 50 characters")
     private String street;
 
     @Column(name="postcode")
+    @NotBlank(message = "Postcode is mandatory")
+    @Size(min = 5, max = 5, message = "Postcode must have 5 characters")
     private String postcode;
 
+    @NotBlank(message = "City is mandatory")
+    @Size(max = 50, message = "City must not exceed 50 characters")
     private String city;
 
     private String phone;
 
-    @OneToOne(fetch = FetchType.LAZY, mappedBy = "contact", cascade = CascadeType.ALL)
+    @OneToOne(mappedBy = "contact", cascade = CascadeType.ALL)
     private SupplierEntity supplier;
 }
\ No newline at end of file
diff --git a/src/main/java/de/szut/webshop/model/SupplierEntity.java b/src/main/java/de/szut/webshop/model/SupplierEntity.java
index fc15eaf..649d143 100644
--- a/src/main/java/de/szut/webshop/model/SupplierEntity.java
+++ b/src/main/java/de/szut/webshop/model/SupplierEntity.java
@@ -1,6 +1,8 @@
 package de.szut.webshop.model;
 
 import jakarta.persistence.*;
+import jakarta.validation.constraints.NotNull;
+import jakarta.validation.constraints.Size;
 import lombok.Data;
 import lombok.Getter;
 import lombok.Setter;
@@ -14,14 +16,13 @@ import java.util.Set;
 @Table(name = "Supplier")
 public class SupplierEntity {
     @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
+    @NotNull
+    @Size(max = 50, message = "Name must be less than 50 characters")
     private String name;
 
-    private String address;
-
-    private String phone;
-
     @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
     private ContactEntity contact;
 
diff --git a/src/main/java/de/szut/webshop/service/SupplierService.java b/src/main/java/de/szut/webshop/service/SupplierService.java
index ab3f998..a719fa2 100644
--- a/src/main/java/de/szut/webshop/service/SupplierService.java
+++ b/src/main/java/de/szut/webshop/service/SupplierService.java
@@ -1,6 +1,5 @@
 package de.szut.webshop.service;
 
-import de.szut.webshop.dto.AddSupplierDto;
 import de.szut.webshop.model.SupplierEntity;
 import de.szut.webshop.repository.SupplierRepository;
 import org.springframework.stereotype.Service;
@@ -18,22 +17,14 @@ public class SupplierService {
         return supplierRepository.findById(id).orElseThrow();
     }
 
-    public void createSupplier(AddSupplierDto supplier) {
-        SupplierEntity supplierEntity = new SupplierEntity();
-
-        supplierEntity.setName(supplier.getName());
-        supplierEntity.setAddress(supplier.getStreet());
-        supplierEntity.setPhone(supplier.getPhone());
-
-        supplierRepository.save(supplierEntity);
+    public void createSupplier(SupplierEntity supplier) {
+        supplierRepository.save(supplier);
     }
 
     public SupplierEntity updateSupplier(Long id, SupplierEntity supplier) {
         SupplierEntity supplierToUpdate = supplierRepository.findById(id).orElseThrow();
 
         supplierToUpdate.setName(supplier.getName());
-        supplierToUpdate.setAddress(supplier.getAddress());
-        supplierToUpdate.setPhone(supplier.getPhone());
 
         return supplierRepository.save(supplierToUpdate);
     }