我的查询 return 一个空列表而不是一个条目

Question

我正在尝试从 table 获取我的用户：

我通过表格保存了这些值（所以 cayenne 配置似乎不错）。

UserInfoFactory class 是：

public class UserInfoFactory extends _UserInfo implements Serializable {
    private static final long serialVersionUID = 1L;

    public static ObjectContext getContext() {
        @SuppressWarnings("deprecation")
        ServerRuntime runtime = new ServerRuntime("cayenne-myapplication.xml");
        return runtime.newContext();
    }

    @SuppressWarnings("unchecked")
    public static List<UserInfoFactory> getUsersInfo() {

        SQLTemplate select = new SQLTemplate(UserInfoFactory.class,
                "SELECT * FROM mam.userinfo");

        return getContext().performQuery(select);
    }
}

我的 _UserInfo class 是：

package com.example.myapplication.model;

import org.apache.cayenne.CayenneDataObject;

/**
 * Class _UserInfo was generated by Cayenne.
 * It is probably a good idea to avoid changing this class manually,
 * since it may be overwritten next time code is regenerated.
 * If you need to make any customizations, please use subclass.
 */
public abstract class _UserInfo extends CayenneDataObject {

    public static final String ADDRESS_PROPERTY = "address";
    public static final String EMAIL_PROPERTY = "email";
    public static final String FIRSTNAME_PROPERTY = "firstname";
    public static final String LASTNAME_PROPERTY = "lastname";
    public static final String PHONENUMBER_PROPERTY = "phonenumber";
    public static final String USERPASSWORD_PROPERTY = "userpassword";
    public static final String USERPRIVILEGES_PROPERTY = "userprivileges";

    public static final String USERID_PK_COLUMN = "USERID";

    public void setAddress(String address) {
        writeProperty(ADDRESS_PROPERTY, address);
    }
    public String getAddress() {
        return (String)readProperty(ADDRESS_PROPERTY);
    }

    public void setEmail(String email) {
        writeProperty(EMAIL_PROPERTY, email);
    }
    public String getEmail() {
        return (String)readProperty(EMAIL_PROPERTY);
    }

    public void setFirstname(String firstname) {
        writeProperty(FIRSTNAME_PROPERTY, firstname);
    }
    public String getFirstname() {
        return (String)readProperty(FIRSTNAME_PROPERTY);
    }

    public void setLastname(String lastname) {
        writeProperty(LASTNAME_PROPERTY, lastname);
    }
    public String getLastname() {
        return (String)readProperty(LASTNAME_PROPERTY);
    }

    public void setPhonenumber(Integer phonenumber) {
        writeProperty(PHONENUMBER_PROPERTY, phonenumber);
    }
    public Integer getPhonenumber() {
        return (Integer)readProperty(PHONENUMBER_PROPERTY);
    }

    public void setUserpassword(String userpassword) {
        writeProperty(USERPASSWORD_PROPERTY, userpassword);
    }
    public String getUserpassword() {
        return (String)readProperty(USERPASSWORD_PROPERTY);
    }

    public void setUserprivileges(Short userprivileges) {
        writeProperty(USERPRIVILEGES_PROPERTY, userprivileges);
    }
    public Short getUserprivileges() {
        return (Short)readProperty(USERPRIVILEGES_PROPERTY);
    }

}

我正在调用这样的方法：

List<UserInfoFactory> users = UserInfoFactory.getUsersInfo();

但用户列表 return 为空。

那不应该是空的，而是一个值（测试用户）。

我做错了什么？

谢谢，

Answer 1

Cayenne 使用 return null 而不是对象的原因是 PK 字段在结果集中未找到或其值为 NULL。在你的情况下，我认为 Cayenne 在结果中找不到 PK，因为它似乎被定义为 userid id DB，在 Cayenne 代码中我看到它是 USERID.

请允许我就您的代码给您一些一般性建议。为每个请求创建 ServerRuntime 并不是真正有效的解决方案，您应该将其保留为应用程序单例，如果您使用的是旧版本的 Cayenne，请参阅 for details. Moreover ObjectSelect (or SelectQuery）是一种更好（并且确实更灵活）的选择对象的方式。

你可以这样使用它：

List<UserInfoFactory> result = ObjectSelect.query(UserInfoFactory.class)
                                     .select(context);

我的查询 return 一个空列表而不是一个条目

My query return a null list instead of one entry

mysql

jakarta-ee

apache-cayenne