I am trying to generate schema from the DataNucleus SchemaTool for a mysql database, that will store countries and states. Here is a sample of that code:
#PersistenceCapable
Public class State{
private String shortCode;
private String fullName;
#Column(allowsNull = "true",name="country_id")
private Country countryId;
}
The following are my schemaGeneration properties:
datanucleus.ConnectionDriverName=com.mysql.jdbc.Driver
datanucleus.ConnectionURL=jdbc:mysql://localhost:3306/geog
datanucleus.ConnectionUserName=geog
datanucleus.ConnectionPassword=geogPass
datanucleus.schema.validateTables=true
datanucleus.mapping.Catalog=geog
datanucleus.mapping.Schema=geog
In my Country class as well, I have a mapping from a Collection, so that the FK reference for States to the Country table is built correctly.
But there is one problem. In the SQL script generated, the Index part has the Schema name as part of the index name itself, which fails the entire script. Here is that piece:
CREATE INDEX `GEOG`.`MST_STATE_N49` ON `GEOG`.`MST_STATE` (`COUNTRY_ID`);
Notice the schema name in the GEOG.MST_STATE_N49 part of the index' name.
I tried setting the schema and catalog name to blank but that yields a ''.MST_STATE_N49 which still fails.
I am using MySQL Server 5.7.17 using the 5.1.42 version of the JDBC driver (yes, not the latest) on Data nucleus JDO 3.1
Any hints on how I can get rid of the schema/catalog name in the generated DDL?
Why are you putting "datanucleus.mapping.Schema" when using MySQL ? MySQL doesnt use schema last I looked. Similarly the "datanucleus.mapping.Catalog" is effectively defined by your URL! MySQL only actually supports JDBC catalog, mapping on to "database", as per this post. Since DataNucleus simply uses the JDBC driver then catalog is the only useful input.
Consequently removal of both schema and catalog properties will DEFAULT to the right place.
After the comment above from Neil Stockton, I commented out both the properties and it worked. Effectively, this is what is needed:
datanucleus.ConnectionDriverName=com.mysql.jdbc.Driver
datanucleus.ConnectionURL=jdbc:mysql://localhost:3306/geog
datanucleus.ConnectionUserName=geog
datanucleus.ConnectionPassword=geogPass
datanucleus.schema.validateTables=true
Hopefully, I can get the answer to the other question (Pt. 2 in my reply-comment above) as well.
Related
I have to do a project using JPA + Hibernate in which I'm using 3 dialects: MySQL5InnoDBDialect, MSSQL2012Dialect and Oracle12cDialect.
Right now I have a specification which is telling me that for some column from:
Oracle database, I have to use NVARCHAR2(LENGTH) data type
MySql database, I have to use VARCHAR(LENGTH) data type
MSSQL database, I have to use NVARCHAR(LENGTH) data type
... and here is my problem..
If I use:
#Column(name="columnName" length = 255)
private String columnName;
hibernate generates varchar(255) and this is good just for MySQL
If I use:
#Column(name="columnName", columnDefinition="nvarchar2(255)")
private String columnName;
it's not possible in MySQL, i get error because of columnDefinition, but in oracle is okay
I tried to customize MySQL dialect creating
public class CustomMySQL5InnoDBDialect extends MySQL5InnoDBDialect{
public CustomMySQL5InnoDBDialect() {
super();
registerColumnType(Types.NVARCHAR, "nvarchar2($l)");//$l not $1
registerHibernateType(Types.NVARCHAR, StandardBasicTypes.STRING.getName());
}
}
and giving this class in hibernate configuration for MySQL dialect.
I have the same problem in MySQL if I'm using columnDefinition property.
Can you help with this problem please?
The solution is to make use of the feature that the JPA API spec provides you with for just this situation. Define a file orm.xml for each datastore that you need to support, and enable the requisite one when using each database. See this link for details of the file format. That way you don't need to think about hacking the internal features of whichever JPA provider you are using, and you also retain JPA provider portability, as well as database portability
The idea of putting schema specific information info (static) Java annotations is an odd one, even more so when wanting database portability.
I have transfered my project from MySQL to PostgreSQL and tried to drop the column as result of previous issue, because after I removed the problematic column from models.py and saved. error didn't even disappear. Integer error transferring from MySQL to PostgreSQL
Tried both with and without quotes.
ALTER TABLE "UserProfile" DROP COLUMN how_many_new_notifications;
Or:
ALTER TABLE UserProfile DROP COLUMN how_many_new_notifications;
Getting the following:
ERROR: relation "UserProfile" does not exist
Here's a model, if helps:
class UserProfile(models.Model):
user = models.OneToOneField(User)
how_many_new_notifications = models.IntegerField(null=True,default=0)
User.profile = property(lambda u: UserProfile.objects.get_or_create(user=u)[0])
I supposed it might have something to do with mixed-case but I have found no solution through all similar questions.
Yes, Postgresql is a case aware database but django is smart enough to know that. It converts all field and it generally converts the model name to a lower case table name. However the real problem here is that your model name will be prefixed by the app name. generally django table names are like:
<appname>_<modelname>
You can find out what exactly it is by:
from myapp.models import UserProfile
print (UserProfile._meta.db_table)
Obviously this needs to be typed into the django shell, which is invoked by ./manage.py shell the result of this print statement is what you should use in your query.
Client: DataGrip
Database engine: PostgreSQL
For me this worked opening a new console, because apparently from the IDE cache it was not recognizing the table I had created.
Steps to operate with the tables of a database:
Database (Left side panel of the IDE) >
Double Click on PostgreSQL - #localhost >
Double Click on the name of the database >
Right click on public schema >
New > Console
GL
I am trying to create mysql table using groovy domain class. I have one master table and other table with has reference to field in the master table.
Let me explain more clearly. I have a master table
QualificationMaster
`````````````````
QualificaitonID
QualificationName
QualificaitonDuration
UserQualificationMap
```````````````````
Username
Email
QualificationID (this field refers to QualificationID in QualificationMaster)
Please help me in getting this done by using groovy domain class with sample snippet...I searched a lot but I find it so confusing..please help me as i am very new to groovy and helps me a lot. I am using GGTS IDE for this.
Check this out:
class QualificationMaster{
String QualificationName
Integer QualificaitonDuration
}
class UserQualificationMap{
String Username
String Email
QualificationMaster Qualification
}
You do not have to use QualificationMaster.QualificaitonID as primary key for QualificationMaster. QualificationMaster.id is created by default for each domain class (you can check it in your db).
Therefore you can make a reference to QualificationMaster from UserQualificationMap. It will be mapped as QualificationMaster's primary key in UserQualificationMap table.
Moreover try to use shorter and lowercased names for properties in your domain classes. For example change QualificationMaster.QualificationName to QualificationMaster.name and QualificationMaster.QualificaitonDuration to QualificationMaster.duration.
I am new to Java EE (and to Netbeans). I have am trying to automatically generate entity classes from my mysql database... For simple relationships it works, but for the following it always fails:
i get the following error:
Internal Exception: Exception [EclipseLink-7220] (Eclipse Persistence Services - 2.3.2.v20111125-r10461): org.eclipse.persistence.exceptions.ValidationException
Exception Description: The #JoinColumns on the annotated element [field tblExpandituresTranx] from the entity class [class entities.restaurant.TblContents] is incomplete. When the source entity class uses a composite primary key, a #JoinColumn must be specified for each join column using the #JoinColumns. Both the name and the referencedColumnName elements must be specified in each such #JoinColumn.. Please see server.log for more details.
I think... I have some error in my database or perhaps EclipseLink JPA tool is kaput!
please help!
Could be that your schema is upside down.
Or you could actually read the exception you're getting and figure out what it's telling you:
The #JoinColumns on the annotated element [field tblExpandituresTranx] from the entity class [class entities.restaurant.TblContents] is incomplete. When the source entity class uses a composite primary key, a #JoinColumn must be specified for each join column using the #JoinColumns. Both the name and the referencedColumnName elements must be specified in each such #JoinColumn
Looks like you've got an incomplete specification for the JOIN.
I solved the problem myself...
Apparently JPA has a problem with multiple primary keys in bridge tables. So, instead of having foreign keys as primaries I just converted them to unique indexed and everything worked just fine!! wuhu!!
I am using LINQ to SQL to connect to database from my application. When I am changing environment from production to staging, I can update my connection string in web.config.
But there is one more value I need to update when environment changes. That is database name. In LINQ to SQL designer file, database name is mentioned as attribute like-
[System.Data.Linq.Mapping.DatabaseAttribute(Name="somedbname")]
How can I pick up value of Name dynamically from some config file?
Any help is really appreciated.
as mentioned on the
http://msdn.microsoft.com/en-us/library/system.data.linq.mapping.databaseattribute.name.aspx
"The DatabaseName is used only if the connection itself does not specify the database name."
so you can delete this attribute and all is gonna work fine!
I've used a wrapper class to provide a context along the lines of
public DataContext Context = new DataContext(SqlConnectionString); //much simplified
I fixed this problem by editing the .dbml file outside of Visual Studio (the designer doesn't seem to allow access to the DatabaseAttribute) and getting rid of the name property here:
<Database Name="BadName" Class="OutputDataContext" xmlns="http://schemas.microsoft.com/linqtosql/dbml/2007">
(note that the accepted answer is no longer correct: this attribute was overriding my connection string)