如何在 Bloomberg Python API 订阅中检查订阅状态是否错误？

Question

I am writing a program for doing Bloomberg data-feed check using the subscription method of Python API. I am close to finishing it and I am now trying to cover edge cases such as a failed subscription. I want to check if a subscription has failed. If it fails, I will write it into a file named BadSubscription.txt.

One of he example programs that come with Bloomberg API package, SimpleSubcriptionExample.py, has just 1 line of code for Subscription Status so it doesn't give me a clear idea.

try:
    # Process received events
    eventCount = 0
    while(True):
       # We provide timeout to give the chance to Ctrl+C handling:
       event = session.nextEvent(15000)
       for msg in event:
           if event.eventType() == blpapi.Event.SUBSCRIPTION_STATUS or \
                   event.eventType() == blpapi.Event.SUBSCRIPTION_DATA:
               print("%s - %s" % (msg.correlationIds()[0].value(), msg))
           else:
               print(msg)

The above code prints the following when a subscription fails for subscribing to a security/equity that doesn't exist:

SubscriptionFailure = {
    reason = {
        errorCode = 2
        description = "Invalid security, rcode = -11"
        category = "BAD_SEC"
        source = " [nid:3924]:bbdbm10"
    }
}

And when a subscription is successful it prints:

SubscriptionStarted = {
    exceptions[] = {
    }
    streamIds[] = {
        "1"
    }
    receivedFrom = {
        address = "localhost:8194"
    }
    reason = "Subscriber made a subscription"
}

What I want to do is write an if statement for my program to catch the SubscriptionFailure and write the message to the file:

for msg in event:
    if (event.eventType() == blpapi.Event.SUBSCRIPTION_STATUS 
           and (**the condition to catch the error**)):
        f = open("BadSubscription.txt", "a+")
        f.write(msg)

I am looking for a condition to use in my if statement.

I tried reading the following repository but it doesn't explain much, too. https://bloomberg.github.io/blpapi-docs/python/3.13/_autosummary/blpapi.Session.html?highlight=subscription%20status

Answer 1

I first tried

msg.correlationIds()[0].value().find("SubscriptionFailure")!=-1

as the condition but that didn't work.

Thanks to @assylias I found the solution.

for msg in event:
    if (event.eventType() == blpapi.Event.SUBSCRIPTION_STATUS 
            and msg.messageType() == "SubscriptionFailure"):
        f = open("BadSubscription.txt", "a+")
                    s = ""
                    if msg.getElement("reason").getElement("errorCode").getValueAsInteger() !=12:
                        s = msg.toString()
                    f.write(s)

The above code writes the following to my file:

SubscriptionFailure = {
    reason = {
        errorCode = 2
        description = "Invalid security, rcode = -11"
        category = "BAD_SEC"
        source = " [nid:235]:bbdbm10"
    }
}