CODEWITHSUNDEEP
.netentity-frameworkrepository
Jekas
Jekas

Reputation: 578

General persist method in Entity Framework - inserting or updating (if exists) entity

What is the best solution in entity framework to implement generic persist method?

For example there is a Company entity:

public class Company
{
    public Company()
    {
        Id = Guid.NewGuid();
    }

    public Guid Id { get; set; }

    public string Name { get; set; }
}

The Id property can be generated before entity is stored into the Database.

So the task is to implement Persist method:

public class Repository
{
    private DbSet<Company> _dbSet;

    public void Persist(Company company)
    {
        // How to implement body here to Add entity if it doesn't exists yet
        // or Modify it in opposit case?
        // In terms of database entity record is required to be inserted or updated.
    }
}

Thanks!

Upvotes: 2

Views: 795

Answers (1)

Slauma
Slauma

Reputation: 177133

In your example where you can't recognize if a Company instance is new or has been formerly loaded from the database you must query the DB:

public void Persist(Company company)
{
    var companyInDb = _dbSet.SingleOrDefault(c => c.Id == company.Id);
    if (companyInDb != null)
    {
        _context.Entry(companyInDb).CurrentValues.SetValues(company);
    }
    else
    {
        _dbSet.Add(company);
    }
    _context.SaveChanges();
}

As you can see, you need a reference to the context _context in your repository.

An alternative approach is possible if you mark the company as new or loaded from the DB, for example with a special constructor:

public class Company
{
    public Company()
    {
    }

    public Company(bool isNew)
    {
        Id = Guid.NewGuid();
        _isNew = isNew;
    }

    public Guid Id { get; set; }
    public string Name { get; set; }

    private bool _isNew;
    public IsNew { get { return _isNew; } }
}

The Persist method wouldn't then need to load the original:

public void Persist(Company company)
{
    if (!company.IsNew)
    {
        _context.Entry(company).State = EntityState.Modified;
    }
    else
    {
        _dbSet.Add(company);
    }
    _context.SaveChanges();
}

Note that all this only updates scalar properties of the company, not relationships.

Upvotes: 4

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