I have an existing hierarchy of Java classes that represents a model in my application.
For example, I have Account<-User Account<-Company classes.
How to store this hierarchy in OrientDB ? Is it possible to automatically create OrientDB Classes based on the existing models ?
OrientDB automatically manages POJO with no need to configure mapping before using it.
// OPEN THE DATABASE
OObjectDatabaseTx db = new OObjectDatabaseTx ("remote:localhost/petshop").open("admin", "admin");
// REGISTER THE CLASS ONLY ONCE AFTER THE DB IS OPEN/CREATED
db.getEntityManager().registerEntityClasses("foo.domain");
// CREATE A NEW PROXIED OBJECT AND FILL IT
Account account = db.newInstance(Account.class);
account.setName( "Luke" );
account.setSurname( "Skywalker" );
City rome = db.newInstance(City.class,"Rome", db.newInstance(Country.class,"Italy"));
account.getAddresses().add(new Address("Residence", rome, "Piazza Navona, 1"));
db.save( account );
For more information look at: OrientDB Object API.
Related
I'm aiming to show virtual entity records on a subgrid on the form of a custom entity (say, Client). I have created a virtual entity, custom data provider and registered the required plugin. So far things work fine; I load the form, subgrid loads with the data from external webservice.
Now, I want to pass a string field on the form (say, Client.ExternalId) as a parameter to the retrieveMultiple plugin so that I can use this field to query the datasource.
The retriveMultiple plugin steps (registered automatically when custom data provider was set up) show that it was registered on the virtual entity and not Client entity. Since it gets executed on load of the subgrid on the Client entity form I am not sure how I can pass a field to the plugin.
Can someone please give some guidance on how to achieve this?
Version 1710 (9.2.22103.194) online
Thanks
If the virtual entity has an N:1 relationship with the main entity and the subgrid is configured to show related records, then you can do like this:
// first, get the whole query
var query = context.InputParameterOrDefault<QueryExpression>("Query");
// next, get the linkEntity and then the linkFilter
var linkFilter = query.LinkEntities.FirstOrDefault(x => x.LinkToEntityName == "mainEntityLogicalName").LinkCriteria;
// next, get the main entity id
var mainEntityId = linkFilter.Conditions.FirstOrDefault(x => x.AttributeName == "mainEntityIdFieldName").Values.FirstOrDefault() as Guid?;
// finally, retreive main entity to get the Client.ExternalId
var mainEntity = orgSvc.Retrieve("mainEntityLogicalName", mainEntityId.Value, new ColumnSet("Client.ExternalId"));
var clientExternalId = mainEntity.GetAttributeValue<string>("Client.ExternalId");
I am developing an Asp.Net mvc5 project. I am using Entity Framework code first approach to interact with the database. I am using Identity System for user authentication. But I am having a problem with integrating the AspNetUsers table from identity system to my model. My identity system database context and model database context class are different because I am using built in included identity system.
But connection string are same. Both use default connection string. But model is in different project. Now I am in the middle of the project. I have existing model classes mapped with tables in database. I created an user account from UI, so required tables(AspNetUsers table included) for identity system are auto-migrated. Now I want to create model class to map AspNetUsers table because I want to create relationship with between that AspNetUsers table and one of the existing tables. So I created a model class named "AspNetUser" class in my model project. Then I created properties for that class according to AspNetUsers table in database. Then I add migration and update database for my model. It gave me following error.
There is already an object named 'AspNetUsers' in the database.
What I can think is to delete AspNetUsers table and update database. But if I delete it, I have to delete other tables required for identity system because they have FK relationship. I do not want it. Second way I can think is to delete all required tables for identity system. Then migrate AspNetUser model class. Then delete that class and register new account from UI. So all required tables for identity system will be created again.
Second way also, I have to delete tables and happen data loss. How can I migrate overriding the existing AspNetUsers table? Is it possible? What is the best way to integrate AspNetUsers table to my model?
This is Configuration class in Migration folder
internal sealed class Configuration : DbMigrationsConfiguration<PatheinFashionStore.Domain.Concrete.StoreContext>
{
public Configuration()
{
AutomaticMigrationsEnabled = true;
AutomaticMigrationDataLossAllowed = true;
}
protected override void Seed(PatheinFashionStore.Domain.Concrete.StoreContext context)
{
}
}
This is my context initializer class
public class ContextInitializer : System.Data.Entity.CreateDatabaseIfNotExists<StoreContext>
{
protected override void Seed(StoreContext context)
{
}
}
If it is not possible, what would be the best way?
I need to know information about entities, tables, mappings, keys etc for the given instance of DbContext. In Entity Framework 6 I was writing edmx like this:
System.Data.Entity.Infrastructure.EdmxWriter.WriteEdmx(dbContext, xmlWriter);
which I then used to build my own data model (this is needed for a tool which supports loading data from different sources). How do I get such information for the new EF Core (previous EF 7)? I could use Reflection, but this will give me only the conceptual schema, while I also need mappings and storage schema. I've been looking through the EF source code for a while now, but don't seem to find any object, that stores all the required data.
This should get you started
using (var ctx = new TestContext())
{
var entityType = ctx.Model.FindEntityType(typeof (Entity_Basic));
var tableName = entityType.SqlServer().TableName;
var columnName = entityType.GetProperties().ToList()[0].SqlServer().ColumnName;
}
I'm using EF5 Model First. I don't really understand what are the auto-generated classes from the EDM. According to some documentation this classes are POCOs but why are they used in the context ?
Assuming I have a Student entity, then I get a Student POCO class and a DbSet StudentSet property in my context.
Will this next instructions put a POCO in my database ?
MyContext.StudentSet.Add(johndoe);
MyContext.SaveChanges();
So EF uses POCO to transfer data ? Actually I miss the step when POCO exchange data with entities or DTO and when the entities put data in the database.
The generated classes from the EDM is the ORM / Persistence classes. You use that classes to query / make changes from / to database. You need to translate any DTO object to POCO object when about making changes to database.
ORM is about mapping object to data in database, instead of dealing with insert into syntax to insert record to database in the application, you use StudentSet.Add to add a new data. The johndoe information will be translated into sql syntax, EF will map each property to each column when translating it into query.
The Add method will store the johndoe information as Added in the memory but it will not be executed right away to the database. If you have another Add method, it will be marked as Added too. The moment you call SaveChanges, all the changes will be saved into database by sending a generated query.
The mapping between DTO and EF entity happens before you add the johndoe. You might have another DTO class that is used in the UI. You need to map it manually or using mapper library to create a POCO object from a DTO object. For example:
// studentDto as parameter
var johndoe = new Student
{
Name = studentDto.StudentName,
Age = studentDto.StudentAge
};
MyContext.StudentSet.Add(johndoe);
// studentDto might have another information as well
var johndoeSubject = new Subject
{
Name = studentDto.SubjectName,
Years = studentDto.SubjectYears
};
MyContext.SubjectSet.Add(johndoeSubject);
MyContext.SaveChanges();
I have an app engine(Java) connected android application. I have an entity with some fields. Now I want to add another field to the entity in the new version of the app engine project. But I already have existing entities in the datastore. How can I update existing entities so that it includes the new field?
Add the new field to the model. and you will have it in the datastore, if you want to assign them values , loop through the entities and assign values and put them , other wise the datastore will return None for the records where the new field is not set