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I have a entity class User. I want to add some more properties but to keep them nullable.
What is the annotation used for this in JPA?
I am using JPA in Google App Engine.
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A field can be set to null just by creating an empty Value object. Here is the snippet which would help. Field field = arserveruser. getField("FORM_NAME", 536870915, null);
The JPA specification defines that during ordering, NULL values shall be handled in the same way as determined by the SQL standard. The standard specifies that all null values shall be returned before or after all non-null values. It's up to the database to pick one of the two options.
The normal behavior is indeed returning an empty list if no results are found. If a List<Object> is the return value of the method in the defined interface, the method should never return Null .
@Column(nullable = false) is the JPA way of declaring a column to be not-null. I.e. the former is intended for validation and the latter for indicating database schema details.
Properties are nullable by default in JPA, except primitive types. You can control nullability using the nullable property of the @Column annotation, like so:
//not nullable @Column(nullable = false) private String prop1; //nullable @Column(nullable = true) private String prop2; //default = nullable @Column private String prop3; In your Entity class use Integer, Double, rather than int and double.
@Entity public class AnyTable { ... public double myValue; // !! dont use in this way - this can never be null! public Double myValue; // BETTER ! If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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