Tutorial_03_Explicit_Employee()
{
//----------------------------------------------------------------------------------------------------------
// Create the Stash Client.
StashClient <Employee>
client = StashConfiguration.GetClient <Employee>();
//----------------------------------------------------------------------------------------------------------
// Create the underlying table if it does not already exists
client.CreateTableIfNotExist();
//----------------------------------------------------------------------------------------------------------
// Create an instance of the class
const
string departmentDev = "Dev";
Employee
dataWritten = new Employee {
Department = departmentDev,
EmployeeId = Guid.NewGuid().ToString(),
Name = "John Doe",
SkillLevel = 8,
DateOfBirth = new DateTime(1990, 1, 1)
};
// update the private field
dataWritten.SetAnnualSalary();
//----------------------------------------------------------------------------------------------------------
// Stash it
client.Insert(dataWritten);
// Note: On inserts, updates and merges, the ETag is overwritten from the ETag returned to keep the data
// in sync.
//----------------------------------------------------------------------------------------------------------
// And read it back
Employee
dataRead = client.Get(dataWritten.Department, dataWritten.EmployeeId);
//----------------------------------------------------------------------------------------------------------
// Verify we got back what we put in
Assert.IsTrue(dataWritten.Equals(dataRead));
// Verify that the 2 ETags are identical
Assert.IsTrue(dataRead.ETagInternal == dataWritten.ETagInternal);
//----------------------------------------------------------------------------------------------------------
// Change the Skill level and update the Stash
dataWritten.SkillLevel += 1;
dataWritten.SetAnnualSalary();
client.Update(dataWritten);
//----------------------------------------------------------------------------------------------------------
// Read back the data but this time lets use LINQ
Employee
dataReadUpdated = client.CreateQuery()
.Where(imp => imp.Department == departmentDev &&
imp.EmployeeId == dataWritten.EmployeeId)
.FirstOrDefault();
//----------------------------------------------------------------------------------------------------------
// Again verify that we got back what we put in
Assert.IsTrue(dataWritten.Equals(dataReadUpdated));
// Verify that the 2 ETags are identical
Assert.IsTrue(dataWritten.ETagInternal == dataReadUpdated.ETagInternal);
//----------------------------------------------------------------------------------------------------------
// now attempt to update the data read the first time around
// this should fail and throw an exception since the data was updated since the row was last read and
// so has a stale ETag.
// Uses the implied update mode here by default. That is, if the StashETag attribute is applied to a
// member in the class, implies ETag must match,
bool isSuccess;
try
{
client.Update(dataRead);
isSuccess = false;
}
catch (Exception ex)
{
Assert.IsTrue((ex as StashException).Error == StashError.ETagMatchFailed);
isSuccess = true;
}
Assert.IsTrue(isSuccess);
//----------------------------------------------------------------------------------------------------------
// attempt to update it again but this time ignore ETag matching. This should succeed.
// and dataRead has the latest ETag
client.UpdateUnconditional(dataRead);
//----------------------------------------------------------------------------------------------------------
// now attempt to delete the entity using the data written entity
// this should fail and throw an exception since the data was recently updated and so has a new ETag
// Uses the implied update mode here by default. That is, if the StashETag attribute is applied to a
// member in the class, implies ETag must match,
try
{
client.Delete(dataReadUpdated);
isSuccess = false;
}
catch (Exception ex)
{
Assert.IsTrue((ex as StashException).Error == StashError.ETagMatchFailed);
isSuccess = true;
}
Assert.IsTrue(isSuccess);
//----------------------------------------------------------------------------------------------------------
// now delete the entity unconditionally without the need for ETag Matching.
// Can instead also use client.DeleteUnconditional here too.
client.Delete(dataRead, ETagMatch.Unconditional);
//----------------------------------------------------------------------------------------------------------
// And verify that it was actually deleted
// by attempting to read back the data
var queryable = from imp in client.CreateQuery()
where imp.Department == dataWritten.Department &&
imp.EmployeeId == dataWritten.EmployeeId
select imp;
Assert.IsTrue(queryable.ToList().Count == 0);
//----------------------------------------------------------------------------------------------------------
// Essentially the ETag gist is this.
// Define and decorate a member in your type with an ETag if you want to optimistic concurrency support.
// Stash will keep you ETag in sync across inserts, updates and merges.
// There are multiple ways to implicitly override ETag matching if that is what is wanted.
// The implicit way to disable optimistic concurrency support is not to define an ETag member.
//----------------------------------------------------------------------------------------------------------
// So far so good. This concludes this part of the tutorial. Go Stash!
}
