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Working with POJO classes as schema for mongo db, specifically handling schema changes

I'm using simple Java classes which are the schema for my mongo db table.
There are several frameworks for serialization/ deserialization to/ from JSON and CRUD operations for mongo (I've looked into Jackson serializer and Morphia).
But none of them seems to provide a solution for handling changes:
Let's say I have this class as my schema:
Class Person
{
String name;
int age;
String occupation;
}
In my code, I will probably use a setter in some place for age:
Person newDbEntry = new Person();
newDbEntry.setAge(45);
newDbEntry.setOccupation("Carpenter");
Now let's say that at some point of the development process, it was decided that age field name needs to be changed to "theAge", and it was also decided to remove "occupation" field from this collection completely- to a new table.
The problem that I'm faced with is that all my queries look like this:
JsonObject query = new JsonObject().put("age",new JsonObject().put("$gte", 22);
In other words, all field names are written in queries as Strings (and also in all other mongo APIs- update, findAndModify, etc).
I'm looking for a way to "bind" all mentions of the field "age" in my code with the POJO class- so that when something in the POJO schema changes (like renaming this field), I'll have (ideally) compiler errors in all queries that mention this field.
As it currently stands, changes to schema cause no compiler errors and - more critically - usually no runtime errors. The old string query just quietly returns no results, or something similar. This makes changes to the schema very hard to implement.
How should this be done correctly?

Here's the solution that I ended up using:
Project lombok now supports FieldNames generation:
https://projectlombok.org/features/experimental/FieldNameConstants
So instead of using the name hardcoded as string:
serviceRepository.setField(id, “service.serviceName”, “newName”);
I use:
serviceRepository.setField(id, ConnectivityServiceDetails.Fields.service + "." + ConnectivityService.Fields.serviceName, “newName”);
This way, when we search in Intellij for usages of this field (or try to refactor it), it will find those places also automatically.

How do I configure JPA table name at runtime?

I have an issue where I have only one database to use but I have multiple servers where I want them to use a different table name for each server.
Right now my class is configured as:
#Entity
#Table(name="loader_queue")
class LoaderQueue
I want to be able to have dev1 server point to loader_queue_dev1 table, and dev2 server point to loader_queue_dev2 table for instance.
Is there a way i can do this with or without using annotations?
I want to be able to have one single build and then at runtime use something like a system property to change that table name.

For Hibernate 4.x, you can use a custom naming strategy that generates the table name dynamically at runtime. The server name could be provided by a system property and so your strategy could look like this:
public class ServerAwareNamingStrategy extends ImprovedNamingStrategy {
#Override
public String classToTableName(String className) {
String tableName = super.classToTableName(className);
return resolveServer(tableName);
}
private String resolveServer(String tableName) {
StringBuilder tableNameBuilder = new StringBuilder();
tableNameBuilder.append(tableName);
tableNameBuilder.append("_");
tableNameBuilder.append(System.getProperty("SERVER_NAME"));
return tableNameBuilder.toString();
}
}
And supply the naming strategy as a Hibernate configuration property:
<property
name="hibernate.ejb.naming_strategy"
value="my.package.ServerAwareNamingStrategy"
/>

I would not do this. It is very much against the grain of JPA and very likely to cause problems down the road. I'd rather add a layer of views to the tables providing unified names to be used by your application.
But you asked, so have some ideas how it might work:
You might be able to create the mapping for your classes, completely by code. This is likely to be tedious, but gives you full flexibility.
You can implement a NamingStrategy which translates your class name to table names, and depends on the instance it is running on.
You can change your code during the build process to build two (or more) artefacts from one source.

Filter custom fields not present in database using Apache Cayenne

In my API it is currently possible to filter on all fields that exists in the database.
Filtering is implemented in FilterUtils.java in the API project. This translates the url parameters to a Apache Cayenne search and returns the result to the resource.
In the "Main" project there are generated classes for each database table in com.foo.bar.auto these are extended by classes in com.foo.bar.
The classes in com.foo.bar can have custom functions. An example is Document.getAccount.
Document.getAccount is exposed in the API, but it is not able to filter it because it's not a database field. I need to be able to filter fields like Document.getAccount.
Is it possible to register these functions in Cayenne somehow?
The syntax for searching on custom fields needs to be equal to todays filtering syntax. So when searching for account it should look like this: Document?filter=account(EQ)1234.
Any ideas? All help is appreciated.

Your best bet is to split your filter keys into persistent and non-persistent properties. Then you'd build 2 expressions, one for each subset of keys. Use the first expression to build a query to fetch from DB, and the second one - to filter the returned result in memory:
Expression p = ...
Expression np = ...
SelectQuery query = new SelectQuery(Document.class, p);
List<Document> docs = context.performQuery(query);
List<Document> filteredDocs = np.filterObjects(p);

How to tell Hibernate annotation #Column to be case-sensitive?

I'm trying to do a simple SELECT query in a table named ECM (in uppercase) on a Sybase db with Hibernate. I've annotated my DBO this way :
#Entity
#Table(name="ECM")
public class RelationshipDbo {
...
}
However, I'm facing a "table not found" error : the generated SQL has the table name in lowercase. I cannot change the database configuration to tell it to be case-insensitive.
I've also tried putting quotes like this :
#Table(name="`ECM`")
and this :
#Table(name="'ECM'")
Result : the quotes are added in the query, but the table name is still converted from uppercase to lowercase.
Technical information :
Hibernate 4.3
JPA 1.2
org.hibernate.dialect.SybaseDialect
Have you guys any idea?
EDIT: Also tried this Hibernate changes #Table(name) to lowercase
Then my columns names and table name are automatically quoted, but the names still get lowercased.

I think I have your answer:
Basically, you need to change the naming strategy for you JPA provider. How you do this will depend on how you setup your project.
In my case, using spring boot data I set a property in my application.properties to
spring.jpa.hibernate.naming-strategy=org.hibernate.cfg.EJB3NamingStrategy
Without more details from you I can't give more specifics on how to do this.

My goal is a little different since was trying to create tables upper case and hibernate created them in lower case. Also i was using MySQL not Sybase.
But for me quoting the names like this worked:
#Entity
#Table(name="\"ECM\"")
public class RelationshipDbo {
...
}
Then tables were created upper case. Maybe that helps also for the queries.

What is your Sybase db version ?
SybaseDialect has been deprecated in Hibernate 3.5 and then refactored since Hibernate 4.1 with a bunch of subclasses matching different versions of Sybase. Have you tried one of the subclasses to see if it makes any difference?
org.hibernate.dialect.Sybase11Dialect
org.hibernate.dialect.SybaseAnywhereDialect
org.hibernate.dialect.SybaseASE15Dialect

Try this:
Use backticks as in #Table(name="`ECM`")?
This must work from Hibernate point. If not then problem should be in DB (if i'm not wrong)

Unit testing Hibernate with multiple database catalogs

I have an issue testing a Hibernate application which queries multiple catalogs/schemas.
The production database is Sybase and in addition to entities mapped to the default catalog/schema there are two entities mapped as below. There are therefore three catalogs in total.
#Table(catalog = "corp_ref_db", schema = "dbo", name = "WORKFORCE_V2")
public class EmployeeRecord implements Serializable {
}
#Table(catalog = "reference", schema = "dbo", name="cntry")
public class Country implements Serializable {
}
This all works in the application without any issues. However when unit testing my usual strategy is to use HSQL with hibernate's ddl flag set to auto and have dbunit populate the tables.
This all works fine when the tables are all in the same schema.
However, since adding these additional tables, testing is broken as the DDL will not run as HSQL only supports one catalog.
create table corp_ref_db.dbo.WORKFORCE_V2
user lacks privilege or object not found: CORP_REF_DB
If there were only two catalogs then I think it would maybe be possible to get round this by changing the default catalog and schema in the HSQL database to that one explicitly defined:
Is there any other in-memory database for which this might work or is there any strategy for getting the tests to run in HSQL.
I had thought of providing an orm.xml file which specified the default catalog and schema (overiding any annotations and having all the defined tables created in the default catalog/schema) however these overrides do not seem to be observed when the DDL is executed i.e. I get the same error as above.
Essentially, then I would like to run my existing tests and either somehow have the tables created as they are defined in the mappings or somehow override the catalog/schema definitions at the entity level.
I cannot think of any way to achieve either outcome. Any ideas?

I believe H2 supports catalogs. I haven't used them in it myself, but there's a CATALOGS table in the Information Schema.

I managed to achieve something like this in H2 via IGNORE_CATALOGS property and version 1.4.200
However, the url example from their docs did not seem to work for me, so I added a statement in my schema.xml:
SET IGNORE_CATALOGS = true;