How can I check loglevel with use of If else condition in logstash filter?

# 1. for LogLevel.Error logs
match=> ["message","%{DATESTAMP:timestamp} %{LOGLEVEL:level} %{USERNAME:logger}
%{USER:user} %{URI:url} %{USER:method} %{IPV4:clientIp} %{GREEDYDATA:message}"]
# 2. for other Level logs except Error
match=> ["message","%{DATESTAMP:timestamp} %{LOGLEVEL:level} %{USERNAME:logger}
%{USER:user} %{GREEDYDATA:message}"]

Here are two grok patterns i want to use both.
but whether loglevel is Error and Fatal I need to use number 1 grok pattern.
and the others levels like Warn Debug Trace Info I need the number 2 grok pattern.
How can I do that?

Two options I can think of

One is parse out the level before parsing the rest of the line

grok { match=> [ "message","^%{DATESTAMP:timestamp} %{LOGLEVEL:level} %{GREEDYDATA:restOfLine}" ] }
if [level] in [ "Error", "Fatal" ] {
    grok { match=> ["restOfLine", "^%{USERNAME:logger} %{USER:user} %{GREEDYDATA:message}" ] }
} else {
    grok { match=> ["restOfLine", "^%{USERNAME:logger} %{USER:user} %{URI:url} %{USER:method} %{IPV4:clientIp} %{GREEDYDATA:message}"] }

The other is to try both patterns, the more specific one first, and see which one works:

grok {
    match=> {
        "message" => [
            "%{DATESTAMP:timestamp} %{LOGLEVEL:level} %{USERNAME:logger} %{USER:user} %{URI:url} %{USER:method} %{IPV4:clientIp} % GREEDYDATA:message}",
            "%{DATESTAMP:timestamp} %{LOGLEVEL:level} %{USERNAME:logger} %{USER:user} %{GREEDYDATA:message}"

the first one you suggested it works
Thanks you !

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