Instead of using filter_by I would recommend using filter, it gives you a lot more options. For example (from the manual): db.session.query(MyClass).filter( MyClass.name == ‘some name’, MyClass.id > 5, ) In relation to your case: filters = ( Transaction.amount > 10, Transaction.amount < 100, ) db.session.query(Transaction).filter(*filters)
When you use a Map you always need to associate at least two entities. Let’s say we have an Owner entity that relates to the Car entity (Car has a FK to Owner). So, the Owner will have a Map of Car(s): Map<X, Car> @MapKey The @MapKey will give you the Car’s property used to … Read more
The issue can be a conflict between a java version and a javaassist version. If you’re using the java 8 on your server you should make sure to use the latest javassist version as well. This blog shows the origin of a conflict being inside the thymeleaf which pulls in an older javassist, the solution … Read more
I don’t think there is a blanket statement that you should only ever use a single primary key named id. Most people use a surrogate primary key as an auto generate int, because it isolates the primary key from ever needing to be changed, like if you make the PK the user name and they … Read more
I had the same problem. It is related to the id allocating strategies of Hibernate. Whe n you choose GenerationType.SEQUENCE, Hibernate uses HiLo strategy which allocates IDs in blocks of 50 by default. So you can explicitly set allocationSize value like this: @Id @SequenceGenerator(name=”pk_sequence”,sequenceName=”entity_id_seq”, allocationSize=1) @GeneratedValue(strategy=GenerationType.SEQUENCE,generator=”pk_sequence”) @Column(name=”id”, unique=true, nullable=false) public int getId() { return this.id; … Read more
I solved my problem placing the insertable=false, updatable=false in the @JoinColumn annotation in both classes, Person and Company.
equals() and hashCode() should be implemented using a business key – i.e. a set of properties that uniquely identify the object, but are not its auto-generated ID. in toString() you can put whatever information is interesting – for example all fields. Use your IDE (Eclipse, NetBeans, IntelliJ) to generate all these for you. In order … Read more
Generally, setting batch size to reasonable size and order_insert, order_updates to true can significantly improve performance. In all my projects, I use this configuration as basis: hibernate.jdbc.batch_size = 100 hibernate.order_inserts = true hibernate.order_updates = true hibernate.jdbc.fetch_size = 400 But, yes – there can be memory impact when using batching. But this depends on jdbc driver. … Read more
A simple solution that worked for me was: users = session.query(User.userid, User.name) for user in users: print user would print: <User(1, ‘bob’)> <User(2, ‘joe’)> …
The error ERROR: missing FROM-clause entry for table “agency” …should hint that somewhere in your query you have mistakenly used agency as a table name, without pluralizing it. But where exactly did you do that? The only difference between working and non-working snippets of yours are these bits: joins(:agency). where(agency: {state: ‘active’}). …a-and both lines … Read more