protected async Task CreateDocumentAttachmentAsync <TDocument, TAttachment>(
string documentRecordId,
string partitionKey,
AttachmentTypeMapping <TDocument, TAttachment> attachmentMapping,
TAttachment attachment)
{
var client = GetClient();
var documentUri = UriFactory.CreateDocumentUri(
_dbAccess.DbConfig.DatabaseId, _dbAccess.DbConfig.CollectionName, documentRecordId);
await MakeClientCall(async() =>
{
await client.CreateAttachmentAsync(
documentUri,
attachmentMapping.Writer(attachment),
new MediaOptions
{
// Managed attachments are always stored as octet streams by CosmosDb. The value for content
// type must be set to `application/octet-stream` when storing managed attachments otherwise
// the CosmosDb API produces an error stating that the payload is invalid. This is not the
// case for unmanaged attachments which require the content type to be set for the externally
// stored data.
ContentType = "application/octet-stream",
// The (poorly) named `Slug` property is what CosmosDb uses as the unique identifier for the
// attachment. This is the ID that is used for direct attachment retrieval and must be unique
// within the context of the parent document.
Slug = CreateAttachmentId(documentRecordId, attachmentMapping.AttachmentName)
}, new RequestOptions
{
PartitionKey = new PartitionKey(partitionKey)
});
}, "Failed to create document attachment");
}
private TAttachment DeserialiseAttachment <TDocument, TAttachment>(
AttachmentTypeMapping <TDocument, TAttachment> attachmentMapping,
MediaResponse mediaResponse)
{
try
{
return(attachmentMapping.Reader(mediaResponse.Media));
}
catch (Exception e)
{
throw new NebulaStoreException("Failed to deserialise document attachment", e);
}
}
protected async Task <TAttachment> GetDocumentAttachmentAsync <TDocument, TAttachment>(
string documentRecordId,
string partitionKey,
AttachmentTypeMapping <TDocument, TAttachment> attachmentMapping)
{
var client = GetClient();
var attachmentUri = UriFactory.CreateAttachmentUri(
_dbAccess.DbConfig.DatabaseId,
_dbAccess.DbConfig.CollectionName,
documentRecordId,
CreateAttachmentId(documentRecordId, attachmentMapping.AttachmentName));
var requestOptions = new RequestOptions {
PartitionKey = new PartitionKey(partitionKey)
};
var attachmentResponse = await MakeClientCall(
async() => await client.ReadAttachmentAsync(attachmentUri, requestOptions),
"Failed to read document attachment");
if (attachmentResponse == null)
{
// Attachment not found.
return(default(TAttachment));
}
var mediaResponse = await MakeClientCall(
async() => await client.ReadMediaAsync(attachmentResponse.Resource.MediaLink),
"Failed to read document attachment media");
if (mediaResponse == null)
{
// Media link not found. This would indicate a bug in attachment storage process.
return(default(TAttachment));
}
return(DeserialiseAttachment(attachmentMapping, mediaResponse));
}