[JAVA] How to create member variables with JPA Model

I am a beginner with less than a month of java history. I will leave it as a memorandum for myself.


What I wanted to do

To the model class found from table I wanted to have a parameter with a field name that doesn't exist in the column. In php (I can't recommend it very much), if you declare the variable as it is, you can use it normally. I thought I could do it with java.

A bad example

There is no name column in the Hoge table When you want to get it from the outside or dynamically process it with hoge

@Entity
public class hoge {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    private String name;

If this happens

Caused by: java.sql.SQLException: Column 'name' not found.

I got scolded. Like PHP, it doesn't come in as null It seems to be useless because there is no data to see

Solution

Use the @Transient annotation to exclude it from mapping. Originally it seems to be an annotation to exclude it from persistence It seems that it will be excluded from mapping due to that effect (I'm sorry if it is different)

@Entity
public class hoge {
    @Id
    @Column(name = "id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Integer id;

    @Transient
    private String name;

I'm no longer angry


When studying java You can see how well I was coding in PHP.

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