如何在 Azure Function 隔离进程中访问服务总线消息的 ApplicationProperties？

Question

I have a service bus message that has some ApplicationProperties added to it:

ServiceBusMessage serviceBusMessage
serviceBusMessage.ApplicationProperties.Add("TenantId", tenantId);
serviceBusMessage.ApplicationProperties.Add("Serialization", "JSON");

I need to access these from my Azure function. In a class library style function app I can use ServiceBusReceivedMessage but there doesn't seem to be an equivalent in out of proc ?

Answer 1

After much much digging I realised that the a) there is an overload for the function that includes a FunctionContext class .

so my function has the following signature:

[Function("ExternalProviderChanged")]
        public void ExternalProviderChanged([ServiceBusTrigger("topic",
            "subscription",
            Connection = "ServiceBus")]
            string myQueueItem, FunctionContext context)

and b) inside the FunctionContext the application settings are available, though pretty hidden. The function context exposes the following a context.BindingContext.BindingData which is a context.BindingContext.BindingData . Inside this dictionary is a property UserProperties (yes the old name not the one MS changed it to) and that property contains the ApplicationProperties in JSON format. So for me to get property x I had to do:

IReadOnlyDictionary<string, object> bindingData = context.BindingContext.BindingData;

if (bindingData.ContainsKey("UserProperties") == false)
{
    throw new Exception("Service bus message is missing UserProperties binding data");
}

string userPropertiesStr = bindingData["UserProperties"].ToString();
if (string.IsNullOrEmpty(userPropertiesStr))
{
    throw new Exception("UserProperties is null or empty");
}

JsonDocument json = JsonDocument.Parse(userPropertiesStr);
JsonElement xProp = json.RootElement.GetProperty("x");
string x = serializationProp.GetString();

Answer 2

I might arrive after the battle but there is an easy way to get access to the ApplicationProperties . Just replace the type string (which will return you only the content of the message) with the type Azure.Messaging.ServiceBus.ServiceBusReceivedMessage .

public async Task OnServiceBusAsync(
    [ServiceBusTrigger(topicName: "TOPIC", subscriptionName: "SUBSCRIPTION", Connection = "CONNECTION")]
    Azure.Messaging.ServiceBus.ServiceBusReceivedMessage message,
    ILogger log)

Then you would be able to get access to a specific custom property

    var vcountry = message.ApplicationProperties.GetValueOrDefault("BusinessCountry").ToString();