How do we set header value as null in apache camel exchange message from a processor. I am delivering message to a RabbitMQ exchange and it expects one of the header value to be set as null.
I have tried below approaches from my processor just before delivering the message
exchange.getOut().setHeader("headername","");
But this sets up an empty string to the header.
I also tried
exchange.getOut().setHeader("headername",null);
But in this case the header itself is not visible.
Please let me know if any more information is needed.
The camel-rabbitmq component does not support headers with null values. They are filtered out in the source code.
https://github.com/apache/camel/blob/fab7a58e56e128286f327aba16c09553b26cb846/components/camel-rabbitmq/src/main/java/org/apache/camel/component/rabbitmq/RabbitMQMessageConverter.java#L171
Its a odd requirement/use-case to have to send a null value. And hence why I ask you to explain this more. There must be very good reason to consider changing Camel.
Camel has implemented a fix for this which is backported to the 2.22.1 and 2.21.3 versions and will be available there onwards. For those who are interested to know how this can be achieved, please have a look at Camel-12654 Jira issue.
camel-rabbitmq component and endpoint now support a URI option allowNullHeaders which is false by default. If you want to send custom headers with value as null, set its value to true. For example
from("rabbitmq://hostname:port/exchangeName?allowNullHeaders=true").....
This will configure camel-rabbitmq converter to set headers with null values. Now from your processor, you can do something like this
exchange.getOut().setHeader("headername",null);
This will instruct camel-rabbitmq producer, not to skip and headers which have null values.
Related
I know how to validate property if its match regexp:
regex = "^[{]?[0-9a-fA-F]{8}-([0-9a-fA-F]{4}-){3}[0-9a-fA-F]{12}[}]?$"
for guid, but if its not send in payload - receiving error, is it a simple way to check if property exist and do validate only then?
As per now I check with choice if its exist and if so then do validation, but interested if its more smarter way to do such as if I will have 20 properties to check its becomes very messy flow.
For example 3 validations at the moment:
You could use the Validations Module All validator which seems to cover this use case. Note that you can not customize the exception or message. If this is not acceptable then you could use individual validations in the flow instead.
Example:
<validation:all doc:name="Validation">
<validation:validations>
<validation:is-not-empty doc:name="Validation" value="#[payload.firstName]" message="Firstname cannot be empty"/>
<validation:is-not-empty doc:name="Validation" value="#[payload.lastName]" message="Lastname cannot be empty"/>
<validation:is-number message="Not an adult" value="#[payload.age]" minValue="18" numberType="INTEGER"/>
<validation:is-email email="#[payload.email]" />
<validation:matches-regex message="Invalid SSN" value="#[payload.ssn]" regex="^(?!000|666)[0-8][0-9]{2}-(?!00)[0-9]{2}-(?!0000)[0-9]{4}$"/>
<validation:validate-size value="#[payload.ssn]" min="11" max="11" message="SSN too short"/>
</validation:validations>
</validation:all>
We are migrating from Mule 3 to Mule 4 and in one of our functionalities we need to publish messages to a topic and downstream another mule component is consuming from the queue which is bridged to the topic.
Nothing special here .
To ensure we are able to trace the flow via logs we were sending a 'TrackingId' attribute while publishing messages to the topic ( Mule 3 )
message.setOutboundProperty("XYZ_TrackingID", flowVars['idFromUI']);
return payload;
However when I try the same in Mule 4 we get the following exception :
ERROR 2020-12-20 10:09:12,214 [[MuleRuntime].cpuIntensive.14: [mycomponent].my_Flow.CPU_INTENSIVE
#66024695] org.mule.runtime.core.internal.exception.OnErrorPropagateHandler:
Message : groovy.lang.MissingMethodException: No signature of method:
org.mule.runtime.api.el.BindingContextUtils$MessageWrapper.setOutboundProperty() is applicable for
argument types: (java.lang.String, org.mule.weave.v2.el.ByteArrayBasedCursorStream) values:
[XYZ_TrackingID, "1234567"].\nError type : (set debug level logging or '-
Dmule.verbose.exceptions=true' for
everything)\n********************************************************************************
Checked internet and it seems in Mule4 setting outbound properties is removed as per here
So how do I achieve the same in Mule 4 ?
Don't even try to do that for several reasons. For one message structure is different, so output properties doesn't exist anymore and that method doesn't even exists. On the other hand, in Mule 4 components like the Groovy component can only return a value and cannot change the event. They can not decide to what that value is going to be assigned. You can set the target in the configuration (payload or a variable) and not change the attributes. Note that variables in Mule 4 are referenced by var., not by flowVars. like in Mule 3 (ie vars.idFromUI).
There is a simpler way to set message properties in the Mule 4 JMS connector. Use the properties element and pass it an object with the properties.
For example it could be something like this:
<jms:publish config-ref="JMS_config" destination="${bridgeDestination}" destinationType="TOPIC">
<jms:message>
<jms:body>#["bridged_" ++ payload]</jms:body>
<jms:properties>#[{
XYZ_TrackingID: vars.idFromUI
}]</jms:properties>
</jms:message>
</jms:publish>
It is in the documentation: https://docs.mulesoft.com/jms-connector/1.0/jms-publish#setting-user-properties. I adapted my example from there.
I am not sure if Correlation Id serves the purpose of a tracking ID for your scenario. But you can pass a CID as below. It's there in the mule documentation.
https://docs.mulesoft.com/jms-connector/1.7/jms-publish
<jms:publish config-ref="JMS_config" sendCorrelationId="ALWAYS" destination="#[attributes.headers.replyTo.destination]">
<jms:message correlationId="#[attributes.headers.correlationId]"/>
</jms:publish>
If your priority is to customise the Tracking ID you want to publish, then try passing below format. The key names may differ as per your use case.
<jms:publish config-ref="JMS_config" destination="${bridgeDestination}" destinationType="TOPIC">
<jms:message>
<jms:body>#["bridged_" ++ payload]</jms:body>
<jms:properties>#[{
AUTH_TYPE: 'jwt',
AUTH_TOKEN: attributes.queryParams.token
}]</jms:properties>
</jms:message>
</jms:publish>
In the above the expression attributes.queryParams.token is basically trying to access a token query parameters which is passed to JMS as a property AUTH_TOKEN key-name , consumed by the API through a HTTP Listener or Requestor earlier.
However, attributes.headers.correlationId is a header. Both queryParams and headers are part of attributes in Mule 4.
I am getting some attributes in an API but all getting lost after an HTTP request connector in mule4.
why is it happening?
Look in the connector's configuration properties -> advanced tab for the connector configuration (in this case the HTTP connector's "request" operation) and you'll find a target variable and target value. If you fill in the target with a name - this does an enrichment to avoid overwriting the Mule message. If you leave it blank (the default) it will save the message (attributes, payload) over the top of the existing one - which is what you're seeing now. This mirrors the old mule 3 functionality, but sometimes you want it to leave what you have there alone.
So for the target value you get to pick exactly what gets saved.. If you want just payload: put that in. If you want both payload and attributes - I'd use "message" as that will mean you get both payload and attributes saved in the variable. Of course you may not want as much saved, so feel free to put in whatever dataweave expression you like - so you could even create something with bits from anywhere like:
{
statusCode: attributes.statusCode,
headers: attributes.headers,
payload: payload
}
A connector operation may replace the attributes with those of the operation. If you need to preserve the previous attributes you need to save them to a variable.
This is a default behaviour of MuleSoft. Whenever request crosses to transport barrier it losses existing attributes. You need to preserve attribute before HTTP Request.
When I create a API resource in WSO2 ESB with the uri-template as:
/getbypage_xml/{usid}/{level}/{pageNum}/{lineNum}/?zzjgbm={zzjgbm}
thus, we plan the zzjgbm parameter is enable null, like
/getbypage_xml/{usid}/{level}/{pageNum}/{lineNum}
However, WSO2 ESB response 202 status code, means unacceptable.
Furthermore, if I use the following template
/getbypage_xml?usid={usid}&level={level}&pageNum={pageNum}&lineNum={lineNum}&zzjgbm={zzjgbm}
When I invoke
/getbypage_xml?usid={usid}&level={level}&pageNum={pageNum}&lineNum={lineNum}
or I change the order of parameters, the result is the same.
So, How do I set a uri-template enable the parameter is enable, and at once, when the parameter is existed, I can use get-property('uri.var.zzjgbm') to get
the value of it.
Can someone suggest correct HTTP request header field to use to pass some flag using Rest API call. Can I use 'expect' request element for this use case?
Use Case:
Read client request header-->read the flag(say value is 1 or 0) --> do task A for value=1 or task B for value=0
No, that is not an appropriate use of the Expect header. Depending on your exact use case, you can use (a) a custom header, (b) a query parameter, or (c) embed the flag in the entity being sent to the server. Without more information, it's impossible to say which is most appropriate for your situation.