/// <summary>
/// Writes storage items to storage.
/// </summary>
/// <param name="changes">The items to write to storage, indexed by key.</param>
/// <param name="cancellationToken">A cancellation token that can be used by other objects
/// or threads to receive notice of cancellation.</param>
/// <returns>A task that represents the work queued to execute.</returns>
/// <seealso cref="DeleteAsync(string[], CancellationToken)"/>
/// <seealso cref="ReadAsync(string[], CancellationToken)"/>
public async Task WriteAsync(IDictionary <string, object> changes, CancellationToken cancellationToken)
{
if (changes == null)
{
throw new ArgumentNullException(nameof(changes), "Please provide a StoreItems with changes to persist.");
}
// Ensure Initialization has been run
await InitializeAsync().ConfigureAwait(false);
foreach (var change in changes)
{
var json = JObject.FromObject(change.Value, _jsonSerializer);
// Remove etag from JSON object that was copied from IStoreItem.
// The ETag information is updated as an _etag attribute in the document metadata.
json.Remove("eTag");
var documentChange = new DocumentStoreItem
{
Id = CosmosDBKeyEscape.EscapeKey(change.Key),
ReadlId = change.Key,
Document = json,
};
var etag = (change.Value as IStoreItem)?.ETag;
if (etag == null || etag == "*")
{
// if new item or * then insert or replace unconditionaly
await _client.UpsertDocumentAsync(
_collectionLink,
documentChange,
disableAutomaticIdGeneration : true,
cancellationToken : cancellationToken).ConfigureAwait(false);
}
else if (etag.Length > 0)
{
// if we have an etag, do opt. concurrency replace
var uri = UriFactory.CreateDocumentUri(_databaseId, _collectionId, documentChange.Id);
var ac = new AccessCondition {
Condition = etag, Type = AccessConditionType.IfMatch
};
await _client.ReplaceDocumentAsync(
uri,
documentChange,
new RequestOptions { AccessCondition = ac },
cancellationToken : cancellationToken).ConfigureAwait(false);
}
else
{
throw new Exception("etag empty");
}
}
}
/// <summary>
/// Deletes storage items from storage.
/// </summary>
/// <param name="keys">keys of the <see cref="IStoreItem"/> objects to remove from the store.</param>
/// <param name="cancellationToken">A cancellation token that can be used by other objects
/// or threads to receive notice of cancellation.</param>
/// <returns>A task that represents the work queued to execute.</returns>
/// <seealso cref="ReadAsync(string[], CancellationToken)"/>
/// <seealso cref="WriteAsync(IDictionary{string, object}, CancellationToken)"/>
public async Task DeleteAsync(string[] keys, CancellationToken cancellationToken)
{
if (keys == null || keys.Length == 0)
{
return;
}
// Ensure Initialization has been run
await InitializeAsync().ConfigureAwait(false);
// Parallelize deletion
var tasks = keys.Select(key =>
_client.DeleteDocumentAsync(
UriFactory.CreateDocumentUri(_databaseId, _collectionId, CosmosDBKeyEscape.EscapeKey(key)),
cancellationToken: cancellationToken));
// await to deletion tasks to complete
await Task.WhenAll(tasks).ConfigureAwait(false);
}
public static string SanitizeKey(string key) => CosmosDBKeyEscape.EscapeKey(key);
/// <summary>
/// Reads storage items from storage.
/// </summary>
/// <param name="keys">keys of the <see cref="IStoreItem"/> objects to read from the store.</param>
/// <param name="cancellationToken">A cancellation token that can be used by other objects
/// or threads to receive notice of cancellation.</param>
/// <returns>A task that represents the work queued to execute.</returns>
/// <remarks>If the activities are successfully sent, the task result contains
/// the items read, indexed by key.</remarks>
/// <seealso cref="DeleteAsync(string[], CancellationToken)"/>
/// <seealso cref="WriteAsync(IDictionary{string, object}, CancellationToken)"/>
public async Task <IDictionary <string, object> > ReadAsync(string[] keys, CancellationToken cancellationToken)
{
if (keys == null || keys.Length == 0)
{
// No keys passed in, no result to return.
return(new Dictionary <string, object>());
}
// Ensure Initialization has been run
await InitializeAsync().ConfigureAwait(false);
var storeItems = new Dictionary <string, object>(keys.Length);
var parameterSequence = string.Join(",", Enumerable.Range(0, keys.Length).Select(i => $"@id{i}"));
var parameterValues = keys.Select((key, ix) => new SqlParameter($"@id{ix}", CosmosDBKeyEscape.EscapeKey(key)));
var querySpec = new SqlQuerySpec
{
QueryText = $"SELECT c.id, c.realId, c.document, c._etag FROM c WHERE c.id in ({parameterSequence})",
Parameters = new SqlParameterCollection(parameterValues),
};
var query = _client.CreateDocumentQuery <DocumentStoreItem>(_collectionLink, querySpec).AsDocumentQuery();
while (query.HasMoreResults)
{
foreach (var doc in await query.ExecuteNextAsync <DocumentStoreItem>(cancellationToken).ConfigureAwait(false))
{
var item = doc.Document.ToObject(typeof(object), _jsonSerializer);
if (item is IStoreItem storeItem)
{
storeItem.ETag = doc.ETag;
}
// doc.Id cannot be used since it is escaped, read it from RealId property instead
storeItems.Add(doc.ReadlId, item);
}
}
return(storeItems);
}
