Azure Table Storage: adding item if it does not exist

Question

I'm using Azure Table Storage and using CloudTable object (in Microsoft's library Microsoft.Azure.Cosmos.Table) to add a record. At the moment I have this:

Given my CloudTable object is this: private readonly CloudTable cloudTable;

I have the following code to Upsert a record:

var upsertOp = TableOperation.InsertOrReplace(myRecord);
cloudTable.ExecuteAsync(upsertOp);

However, what I want to do is add a new record only if a record does not already exist. If one already exists then I do not want to add or update the existing.

What is the right approach to doing this? Do I use transactions in some way or can I use the TableOperation.Insert() method (I'm assuming this will throw an exception if an item already exists)?

Answer 1

There is no direct way to check if a record is in the azure table storage or not.

So here are 2 ways to do that:

1.As you mentioned, you can directly use TableOperation.Insert() method with try-catch. If the record already exists, it will throw an error:

   try
    {
        var op1 = TableOperation.Insert(c1);
        table.Execute(op1);
    }
    catch (Exception ex)
    {
        //if the record already exists, an error will be thrown.

    }

2.You can also use the TableOperation.Retrieve() method. If there is no record returned, you can insert a new one. Otherwise, you don't need to insert a new one:

        TableOperation retrieveOperation = TableOperation.Retrieve<CustomerEntity>("partition_key", "row_key");
        TableResult result = table.Execute(retrieveOperation);

        CustomerEntity customer = result.Result as CustomerEntity;
        if (customer != null)
        {
            //if it's not null, you don't need to insert a new record.
        }
        else
        {
            //if it's null, you can insert a new record.
        }