How can multiple DbContexts work together same application? #2598

6 Answer(s)

• 

  0

  ismcagdas created 7 years ago

  Support Team

  Hi,

  We register them for each dbContext seperately. You can see it here <a class="postlink" href="https://github.com/aspnetboilerplate/aspnetboilerplate/blob/master/src/Abp.EntityFramework/EntityFramework/AbpEntityFrameworkModule.cs#L53">https://github.com/aspnetboilerplate/as ... ule.cs#L53</a>

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• 

  0

  bilalhaidar created 7 years ago

  Great.

  Assuming I have 2 business modules.

  Module 1: Contains entities like Car, Driver, etc. (all detailed properties) Module 2: Requires an entity Car but not all of the properties maybe only Id, Name.

  I could create 2 DB Contexts, one in each project. Also, I will have entity Car defined in 2 places, in the first module with all properties and in the second module with only Id and Name.

  Module 1 will be responsible for creating the tables in DB in this case.

  So, in this case, I have 2 BaseRepositories each targeting a different DbContext. However, same entity like Car will appear in 2 DbContext.

  Going back to the source code you referred me to,:

  var primaryKeyType = EntityHelper.GetPrimaryKeyType(entityTypeInfo.EntityType);
                  if (primaryKeyType == typeof(int))
                  {
                      var genericRepositoryType = autoRepositoryAttr.RepositoryInterface.MakeGenericType(entityTypeInfo.EntityType);
                      if (!iocManager.IsRegistered(genericRepositoryType))
                      {
                          var implType = autoRepositoryAttr.RepositoryImplementation.GetGenericArguments().Length == 1
                                  ? autoRepositoryAttr.RepositoryImplementation.MakeGenericType(entityTypeInfo.EntityType)
                                  : autoRepositoryAttr.RepositoryImplementation.MakeGenericType(entityTypeInfo.DeclaringType, entityTypeInfo.EntityType);
  
                          iocManager.Register(
                              genericRepositoryType,
                              implType,
                              DependencyLifeStyle.Transient
                              );
                      }
                  }
  

  This means that IRepository<Car> would map to EfRepository<Module1DbContext, Car, int>. So Module1RepositoryBase will be created based on EfRepository<Module1DbContext, Car, int>.

  Now, in Module 2, given the code referenced above, we will have something similar: IRepository<Car> would map to EfRepository<Module3DbContext, Car, int>. So Module3RepositoryBase will be created based on EfRepository<Module2DbContext, Car, int>.

  Now, in the code, how would it know which DbContext to use?

  Thanks

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• 

  0

  ismcagdas created 7 years ago

  Support Team

  Hi,

  In this case you can create two different Car entitys for each module and map them to same database table. Otherwise it is not possible to find right DbContext in this case.

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• 

  0

  bilalhaidar created 7 years ago

  Excellent! That's what I was hoping it will work.

  Then, I will use one of the DbContexts only to update database, not both will do that.

  Shall I set "SetInitializer(null)" in the Module class, inside the module that I want it to just "READ" from the db and ot change any table structure? Or no need?

  Regards Bilal

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• 

  0

  ismcagdas created 7 years ago

  Support Team

  Hi,

  I think there is no need for that but I couldn't be sure, it is better to try and see :)

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• 

  0

  bilalhaidar created 7 years ago

  Thanks :) As long as I don't hit Update-Database should be fine :)

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