I want to write a unit test that basically verifies an object I add to a foreign collection actually gets saved and retrieved correctly when the DAO saves retrieves the object
Here is my Entity.
#DatabaseTable
public class Question implements Question, Serializable {
#DatabaseField
private String questionText;
#ForeignCollectionField
private ForeignCollection<Answer> answers;
public void addAnswer(Answer answer) {
answers.add(answer);
}
What I want to do is create a Question instance add an Answer object to the collection and pass the Question to my DAO which will persist it. The persistence works fine on regular fields so I know there is no problem there.
How do I go about adding an Answer to the collection? When I create the Question it's answers collection is null. Is it what I have to save the new Question and then retrieve it in order for the answers collection to be non null? Or, do I set the answers to a BaseCollection, LazyCollection instance?
This is a FAQ. The right way to do it is to make use of the Dao.getEmptyForeignCollection(...) method to create a collection that you can add items to. Something like:
Question question = new Question();
query.answers = questionDao.getEmptyForeignCollection("answers");
Answer answer1 = new Answer();
query.answers.add(answer1);
// this can come before the question.answers.add()
questionDao.create(question);
Related
To make updates to a record of SQL Server using Entity Framework Core, I query the record I need to update, make changes to the object and then call .SaveChanges(). This works nice and clean.
For example:
var emp = _context.Employee.FirstOrDefault(item => item.IdEmployee == Data.IdEmployee);
emp.IdPosition = Data.IdPosition;
await _context.SaveChangesAsync();
But is there a standard method if I want to update multiple records?
My first approach was using a list passing it to the controller, but then I would need to go through that list and save changes every time, never really finished this option as I regarded it as not optimal.
For now what I do is instead of passing a list to the controller, I pass each object to the controller using a for. (kind of the same...)
for(int i = 0; i < ObjectList.Count; i ++)
{
/* Some code */
var httpResponseObject = await MyRepositories.Post<Object>(url+"/Controller", Object);
}
And then do the same thing on the controller as before, when updating only one record, for each of the records...
I don't feel this is the best possible approach, but I haven't found another way, yet.
What would be the optimal way of doing this?
Your question has nothing to do with Blazor... However, I'm not sure I understand what is the issue. When you call the SaveChangesAsync method, all changes in your context are committed to the database. You don't have to pass one object at a time...You can pass a list of objects
Hope this helps...
Updating records in bulk using Entity Framework or other Object Relational Mapping (ORM) libraries is a common challenge because they will run an UPDATE command for every record. You could try using Entity Framework Plus, which is an extension to do bulk updates.
If updating multiple records with a single call is critical for you, I would recommend just writing a stored procedure and call if from your service. Entity Framework can also run direct queries and stored procedures.
It looks like the user makes some changes and then a save action needs to persist multiple records at the same time. You could trigger multiple AJAX calls—or, if you need, just one.
What I would do is create an endpoint—with an API controller and an action—that's specific to your needs. For example, to update the position of records in a table:
Controller:
/DataOrder
Action:
[HttpPut]
public async void Update([FromBody] DataChanges changes)
{
foreach(var change in changes)
{
var dbRecord = _context.Employees.Find(change.RecordId);
dbRecord.IdPosition = change.Position;
}
_context.SaveChanges();
}
public class DataChanges
{
public List<DataChange> Items {get;set;}
public DataChangesWrapper()
{
Items = new List<DataChange>();
}
}
public class DataChange
{
public int RecordId {get;set;}
public int Position {get;set;}
}
The foreach statement will execute an UPDATE for every record. If you want a single database call, however, you can write a SQL query or have a stored procedure in the database and pass the data as a DataTable parameter instead.
I want to pass a object to workflow as input parameter, without creating instance of it, as this object is already filled up with lot of sub-objects, and I want to run lot of rules on that object. I want to use
WorkflowInvoker.Invoker(this); Is this possible in Windows Workflow Foundation 4.0, If so, what should I keep in InArguments as the type?
Thanks In Advance,
Thanks for your input....
Sorry, I think I haven't kept the question correctly, I had a business class used by bank customers, class is like this,
public partial class BankName.DTOS.clsCardDetails : BaseClass
{
public string _mBankStatusCode;
protected override string IsCreditCard(HttpContext ctx)
{
Status = ctx.Request.Form["Trans_Status"];
_mBankStatusCode = Status.ToString();
}
}
Now, I have to pass this class object to workflow foundation, I should not create new instance of this class in workflow again. Because in workflow, I want to get the status, so ideally what I thought of passing to workflow is object of "BankName.DTOS.clsCardDetails". That is my question.
InArguments<> to workflow is object of BankName.DTOS.clsCardDetails
Arguments passed into a workflow need to be put into a dictionary and the dictionary is passed into the workflow.
var dictionary = new Dictionary<string, object> { { "BankName", _bankNameObject } };
WorkflowInvoker.Invoke(this, dictionary);
The key must have the same name as your InArgument and your object must have the same type as your InArgument.
You can pass as many arguments as you like into the workflow via the dictionary.
See http://blogs.msdn.com/b/rjacobs/archive/2011/05/26/passing-arguments-to-workflow-activities-again.aspx
I am storing a hash-map in a riak bucket like this:
bucket.store(key, docHashMap).execute();
I would like to store the object with a secondary index.
How would I accomplish this? I am aware that the IRiakObject has a addIndex method, but how do I access the IRiakObject before it is stored?
I would think that what I am trying to do is the expected use-case, yet I am not able to find any documentation or examples on this. If you can point me to one that would be greatly appreciated.
Thanks!
Update:
#Brian Roach answered this on the Riak mailing list and below. Here is the custom class that I wrote that extends the HashMap:
class DocMap extends HashMap<String, Object> {
/**
* Generated id
*/
private static final long serialVersionUID = 5807773481499313384L;
#RiakIndex(name="status") private String status;
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
}
I can still use the object as an ordinary hashmap and store keys and values, but it will also write "status" to a secondary index (and actually end up being called "status_bin" since it's a string.
If you're just passing in an instance of the core Java HashMap ... you can't.
The way the default JSONConverter works for metadata (such as indexes)
is via annotations.
The object being passed in needs to have a field annotated with
#RiakIndex("index_name"). That field can be a Long/Set<Long> or
String/Set<String> (for _int and _bin indexes respectively).
These are not converted to JSON so they won't affect your serialized
data. You can have multiple fields for multiple indexes.
You don't have to append "_int" or "_bin" to the index name in the
annotation - it's done automatically based on the type.
Easiest thing to do woud be to extend HashMap and simply add the
annotated field(s).
I'll preface this question with the following: I know there are a million posts on the internet about the old "An object with the same key already exists in the ObjectStateManager" issue. My scenario is a bit more complicated, I think.
I have a UnitOfWork class which creates a DbContext and passes it to any repository which is called. The pattern I'm using closely follows the Unit of Work tutorial on the ASP.NET site. Unlike the tutorial, my repositories take in Business entities, map them to data entities, and perform some CRUD action. My Business logic only works with Business entities. Here is what I'm trying to do in a sample Business Manager class:
_unitOfWork.Repository.Add(entity);
_unitOfWork.Save(); // context.SaveChanges() under the hood
...Perform some operations on the model...
_unitOfWork.Repository.Update(entity);
_unitOfWork.Save();
Here is a sample Update method from the repository:
public virtual void Update(entity)
{
var dataEntity = // map from business entity to data;
_context.Entry(dataEntity).State = EntityState.Modified;
}
It obviously fails on the last line. Here is where my confusion sets in:
The entity's State is Detached
When I attempt to change the State to Modified or Unchanged, it gives me the ObjectStateManager exception above.
When I attempt to detach the entity from the context (((IObjectContextAdapter)_context).ObjectContext.Detach(entity);) I get an exception about how the entity is not attached to the context, therefore, it cannot detach it. Very confusing (something fundamental I'm missing, for sure).
Many other posts suggest I make a database call, update that entity in the repository, then _unitOfWork.Save(). I don't like this approach. I shouldn't need to make an unnecessary network call to update an entity.
The Update method in the repository needs to handle two scenarios: 1) updating an entity which is not currently tracked by the context, and 2) updating an entity which IS currently tracked by the context. The second piece is what I'm struggling with.
Any help or insight is appreciated.
Thanks!
This means that there already is an object attached to the context with the same key as the new dataEntity. The existing object and the new entity both represent the same entry in the database but they are two different objects.
This may indicate that the lifespan of your _context is too long, but that's hard to judge from your code. It is certain though that the context was previously used to fetch an entity from the database that is subsequently duplicated by var dataEntity = ....
You may have to shorten the lifespan of the context, I can't tell. If you think it's OK you may want to use the Local collection to check whether the entity is already there. That will save the database round trip that Find may still make.
I found a hybrid solution which appears to work:
public virtual void Update(TB entity)
{
var dataEntity = Mapper.Map<TB, TD>(entity);
var pkey = _dbSet.Create().GetType().GetProperty("Id").GetValue(dataEntity);
var entry = _context.Entry(dataEntity);
if (entry.State == EntityState.Detached)
{
var attachedEntity = _dbSet.Find(pkey);
if (attachedEntity != null)
{
var attachedEntry = _context.Entry(attachedEntity);
attachedEntry.CurrentValues.SetValues(dataEntity);
}
else
{
entry.State = EntityState.Modified;
}
}
else
{
entry.State = EntityState.Modified;
}
}
I have some e-commerce code that I use often that uses Linq To SQL for saving orders to the database. I want to remove the tightly coupled Linq to SQL bit and pass in an IRepository instead but I am still a little confused on things.
Say I have a GetCustomer() method on my ICustomerRepository that returns a Customer object.
Do I need it to really return an ICustomer object that gets passed back from that method so if I switch from Linq To SQL to say SubSonic it's not a problem?
I believe I do, if that is the case is there a way in Linq To SQL to easily convert my Linq To SQL Customer object to my ICustomer object like SubSonics ExecuteSingle(Of ) method?
If you want your Customer class to be a plain object with no attachment to LINQ, then you will most likely need to write a mapper method to convert your LINQ-based Customer object to your plain Customer domain object. LINQ to SQL does not have such functionality built-in.
I have begun to wrap my mapping methods in an extension method for readability, and it really helps to keep the Repository code simple. For instance, an example CustomerRepository method my look like:
public Customer GetById(int id)
{
return dataContext.LINQCustomers.Where(c => c.Id == id)
.Single()
.ToDomainObject();
}
and the ToDomainObject() method is defined in an extension method like:
public static class ObjectMapper
{
public static Customer ToDomainObject(this Customer linqObject)
{
var domainObject = null
if (linqObject != null)
{
domainObject = new Customer
{
Id = linqObject.Id,
FirstName = linqObject.FirstName,
LastName = linqObject.LastName
}
}
return domainObject;
}
}
or something similar. You can do the same to convert your domain object back to a LINQ object to pass back into your repository for persistence.
You can have it return a Customer as long as Customer is a plain old .NET object, and not some db-generated entity. Your Customer domain object should have no knowledge about how (or if) it might be persisted to a database, and this is what should be returned from your repository. In your repository you might have some mapping code - this is quite common - that maps from [however you get the data back from its storage location] to your domain object. If you're using Linq-to-sql then this mapping would be from the Linq-To-Sql generated Customer table (and perhaps other tables - your Customer domain object likely won't map 1:1 to a particular table in the database) to your Customer domain object, which would live in a different namespace (and most likely, assembly).
There is no need to make it an ICustomer at all. A repository acts in a way as to make it look as though your persistent instances are in memory.
public interface ICustomerRepository
{
Customer GetByID(int id);
IEnumerable<Customer> GetByName(string name);
Customer GetByVatCode(string vatCode);
}
Some people would additionally include methods such as
void Add(Customer newCustomer);
void Delete(Customer deleted);
void Update(Customer modified);
The latter method implementations would most likely just update a unit of work.
The concept though is that these are just common ways of asking for Customer instances, the repository acts as a way of asking for them without defining how to ask for them.