Configuring message filtering

The plugin makes use of different filters to filter messages.

Topic filtering

For topic filtering, the Filter_topic and Filter_topic_exact_match tags are used.

• Filter_topic

Regular expression or exact text that must match the message topic for the filter to be satisfied. This is optional. By default it would match any topic.

• Filter_topic_exact_match

Indicates whether what is specified in filter_topic will be treated as a regular expression (0) or as an exact text (1). It is optional. Default value is 0.

Examples

Using the Filter_topic and Filter_topic_exact_match filters we can choose the topic to subscribe to.

We can directly indicate the name of the topic or look for a regex pattern in it.

Suppose you have a MQTT topic called:

sensors/temperature/livingroom

EXAMPLE 1 filter_topic_exact_match 1 (Exact text)

You could configure filter_topic by specifying the topic name.

filter_topic sensors/temperature/livingroom

and set filter_topic_exact_match to 1, so that it searches only that topic.

filter_topic_exact_match 1

If instead of specifying the complete topic name, we specify only a part of the topic:

filter_topic sensors/temperature/

I would also agree.

EXAMPLE 2 filter_topic_exact_match 0 (Regular Expression)

You could configure filter_topic by specifying a regular expression that matches the name of the topic you want to subscribe to. For example, the following, which would look to start with “sensors” and end with “livingroom”.

filter_topic ^sensors/.*?/livingroom$

and set filter_topic_exact_match to 0, so that it filters by regular expression, instead of exact text.

filter_topic_exact_match 0

Message filtering

For topic filtering, the Filter_topic and Filter_topic_exact_match tags are used.

• Filter_message

Regular expression or exact text that must match the message for the filter to be satisfied. This is optional. By default it would match any message.

• FIlter_message_exact_match

Indicates whether what is specified in filter_message will be treated as a regular expression (0) or as an exact text (1). It is optional. Default value is 0.

Ejemplos

Using the filters Filter_message and Filter_message_exact_match we can filter the messages to be received.

We can indicate directly the content of the message or look for a regex pattern in it.

Suppose you have a message like this:

{"message":"Move up right",
"status":"active",
"datetime":"2025-02-11T14:30:54.260Z",
"data":{"yaw_rate":0.11466979980468749,
"pitch_rate":0.6159210205078126,
"yaw_direction":"right",
"pitch_direction":"up"}}

EXAMPLE filter_message_exact_match 1 (exact wording)

We could configure filter_message by specifying the message text.

filter_message Move up right

and set filter_topic_exact_match to 1, so that it searches only that topic.

filter_message_exact_match 1

filter_message_exact_match 1

If instead of specifying the complete topic name, we specify only a part of the topic:

filter_message Move up

It would also match