public async Task <ITriggerBinding> TryCreateAsync(TriggerBindingProviderContext context)
{
// Tries to parse the context parameters and see if it belongs to this [CosmosDBTrigger] binder
if (context == null)
{
throw new ArgumentNullException("context");
}
ParameterInfo parameter = context.Parameter;
CosmosDBTriggerAttribute attribute = parameter.GetCustomAttribute <CosmosDBTriggerAttribute>(inherit: false);
if (attribute == null)
{
return(null);
}
ConnectionMode?desiredConnectionMode = _options.ConnectionMode;
Protocol? desiredConnectionProtocol = _options.Protocol;
DocumentCollectionInfo documentCollectionLocation;
DocumentCollectionInfo leaseCollectionLocation;
ChangeFeedProcessorOptions processorOptions = BuildProcessorOptions(attribute);
processorOptions.StartFromBeginning = attribute.StartFromBeginning;
if (attribute.MaxItemsPerInvocation > 0)
{
processorOptions.MaxItemCount = attribute.MaxItemsPerInvocation;
}
ICosmosDBService monitoredCosmosDBService;
ICosmosDBService leaseCosmosDBService;
try
{
string triggerConnectionString = ResolveAttributeConnectionString(attribute);
CosmosDBConnectionString triggerConnection = new CosmosDBConnectionString(triggerConnectionString);
if (triggerConnection.ServiceEndpoint == null)
{
throw new InvalidOperationException("The connection string for the monitored collection is in an invalid format, please use AccountEndpoint=XXXXXX;AccountKey=XXXXXX;.");
}
string leasesConnectionString = ResolveAttributeLeasesConnectionString(attribute);
CosmosDBConnectionString leasesConnection = new CosmosDBConnectionString(leasesConnectionString);
if (leasesConnection.ServiceEndpoint == null)
{
throw new InvalidOperationException("The connection string for the leases collection is in an invalid format, please use AccountEndpoint=XXXXXX;AccountKey=XXXXXX;.");
}
documentCollectionLocation = new DocumentCollectionInfo
{
Uri = triggerConnection.ServiceEndpoint,
MasterKey = triggerConnection.AuthKey,
DatabaseName = ResolveAttributeValue(attribute.DatabaseName),
CollectionName = ResolveAttributeValue(attribute.CollectionName)
};
documentCollectionLocation.ConnectionPolicy.UserAgentSuffix = CosmosDBTriggerUserAgentSuffix;
if (desiredConnectionMode.HasValue)
{
documentCollectionLocation.ConnectionPolicy.ConnectionMode = desiredConnectionMode.Value;
}
if (desiredConnectionProtocol.HasValue)
{
documentCollectionLocation.ConnectionPolicy.ConnectionProtocol = desiredConnectionProtocol.Value;
}
leaseCollectionLocation = new DocumentCollectionInfo
{
Uri = leasesConnection.ServiceEndpoint,
MasterKey = leasesConnection.AuthKey,
DatabaseName = ResolveAttributeValue(attribute.LeaseDatabaseName),
CollectionName = ResolveAttributeValue(attribute.LeaseCollectionName)
};
leaseCollectionLocation.ConnectionPolicy.UserAgentSuffix = CosmosDBTriggerUserAgentSuffix;
if (desiredConnectionMode.HasValue)
{
leaseCollectionLocation.ConnectionPolicy.ConnectionMode = desiredConnectionMode.Value;
}
if (desiredConnectionProtocol.HasValue)
{
leaseCollectionLocation.ConnectionPolicy.ConnectionProtocol = desiredConnectionProtocol.Value;
}
string resolvedPreferredLocations = ResolveAttributeValue(attribute.PreferredLocations);
foreach (var location in CosmosDBUtility.ParsePreferredLocations(resolvedPreferredLocations))
{
documentCollectionLocation.ConnectionPolicy.PreferredLocations.Add(location);
leaseCollectionLocation.ConnectionPolicy.PreferredLocations.Add(location);
}
if (string.IsNullOrEmpty(documentCollectionLocation.DatabaseName) ||
string.IsNullOrEmpty(documentCollectionLocation.CollectionName) ||
string.IsNullOrEmpty(leaseCollectionLocation.DatabaseName) ||
string.IsNullOrEmpty(leaseCollectionLocation.CollectionName))
{
throw new InvalidOperationException("Cannot establish database and collection values. If you are using environment and configuration values, please ensure these are correctly set.");
}
if (documentCollectionLocation.Uri.Equals(leaseCollectionLocation.Uri) &&
documentCollectionLocation.DatabaseName.Equals(leaseCollectionLocation.DatabaseName) &&
documentCollectionLocation.CollectionName.Equals(leaseCollectionLocation.CollectionName))
{
throw new InvalidOperationException("The monitored collection cannot be the same as the collection storing the leases.");
}
monitoredCosmosDBService = _configProvider.GetService(triggerConnectionString, resolvedPreferredLocations);
leaseCosmosDBService = _configProvider.GetService(leasesConnectionString, resolvedPreferredLocations);
if (attribute.CreateLeaseCollectionIfNotExists)
{
await CreateLeaseCollectionIfNotExistsAsync(leaseCosmosDBService, leaseCollectionLocation.DatabaseName, leaseCollectionLocation.CollectionName, attribute.LeasesCollectionThroughput);
}
}
catch (Exception ex)
{
throw new InvalidOperationException(string.Format("Cannot create Collection Information for {0} in database {1} with lease {2} in database {3} : {4}", attribute.CollectionName, attribute.DatabaseName, attribute.LeaseCollectionName, attribute.LeaseDatabaseName, ex.Message), ex);
}
return(new CosmosDBTriggerBinding(
parameter,
documentCollectionLocation,
leaseCollectionLocation,
processorOptions,
monitoredCosmosDBService,
leaseCosmosDBService,
_logger));
}
