HQL對象命名參數

Question

我想知道是否可以從HQL中的名爲參數的對象檢索特定的列。

例

public class Product 
{ 
    private int id; 
    private Supplier supplier; 

    private String name; 
    private String description; 
    private double price; 

    public Product() 
    { 
     super(); 
    } 

    public Product(String name, String description, double price) 
    { 
     super(); 
     this.name = name; 
     this.description = description; 
     this.price = price; 
    } 

    public String getDescription() 
    { 
     return description; 
    } 
    public void setDescription(String description) 
    { 
     this.description = description; 
    } 
    public int getId() 
    { 
     return id; 
    } 
    public void setId(int id) 
    { 
     this.id = id; 
    } 
    public String getName() 
    { 
     return name; 
    } 
    public void setName(String name) 
    { 
     this.name = name; 
    } 

    public Supplier getSupplier() 
    { 
     return supplier; 
    } 
    public void setSupplier(Supplier supplier) 
    { 
     this.supplier = supplier; 
    } 

    public double getPrice() 
    { 
     return price; 
    } 
    public void setPrice(double price) 
    { 
     this.price = price; 
    } 
} 

，你可以看到我創建的產品，並在其內具有一個供應商對象。 所以，當我做HQL，並呼籲

String hql = "from Product as product where product.supplier=:supplier"; 
     Query query = session.createQuery(hql); 
     query.setEntity("supplier",supplier); 
     List results = query.list(); 
     displayProductsList(results); 

但有可能只得到產品的供應商的名稱？ 而不只是整個供應商？

Answer 1

只是不要一個供應商實例傳遞給您的查詢，而是直接通過供應商名稱：

String hql = "from Product as product where product.supplier.name = :supplierName"; 
Query query = session.createQuery(hql); 
query.setString("supplierName", supplier.getName()); 
List results = query.list(); 
displayProductsList(results);