CODEWITHSUNDEEP
linq
Bronzato
Bronzato

Reputation: 9362

object with the same key already exists in the ObjectStateManager

With the following code, I search for a specific Matrix in my repository and then assign it to Shuttle property.

var requestRepository = unitOfWork.Create<Request>();
var matrixRepository = unitOfWork.Create<Matrix>();
...
var matrix = matrixRepository.Find(m => m.MatrixID == matrixID).FirstOrDefault();
request.Shuttle = matrix;
....

This works. I try another alternative. With the following code, I prepare a Matrix object and try to attach it to my repository. 

var requestRepository = unitOfWork.Create<Request>();
var matrixRepository = unitOfWork.Create<Matrix>();
...
var matrix = new Matrix { MatrixID = matrixID };
matrixRepository.Attach(matrix);
request.Shuttle = matrix;
....

This don't work. On the attach statement, I got the error: object with the same key already exists in the ObjectStateManager

Does someone can explain me?

Thanks.

Upvotes: 0

Views: 205

Answers (1)

Likurg
Likurg

Reputation: 2760

At first way, you just find element and put it into matrix. But in second way you try to add matrix which can be already exists in matrixRepository.

EDIT

var matrix = matrixRepository.Find(m => m.MatrixID == matrixID).FirstOrDefault();

this show you that matrixID can be in matrixRepository if not return default.

but here 

var matrix = new Matrix { MatrixID = matrixID };
matrixRepository.Attach(matrix); //if matrixRepository allready have matrix with matrixID  you will get error

you just add it to matrixRepository

Upvotes: 1

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