# Referencing msg variable in environment type parameter

**URL:** <https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786>\
**Category:** General\
**Created:** [29 May 2023 13:45 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786 "2023-05-29T13:45:21Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![elia-sysdesign](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/elia-sysdesign/32/80174_2.png) [@elia-sysdesign](https://discourse.nodered.org/u/elia-sysdesign)\
**Post date:** [29 May 2023 13:45 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786/1 "2023-05-29T13:45:22Z")

</div>

Hello.

I have defined a subflow that logs a message to a table in a database by calling a stored procedure _sp\_write\_execution\_log_.

I have configured the following environment variables:  
 ![Screenshot from 2023-05-29 15-34-48](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/f/0/f07de24bfe4018df878e779b73981b44de3f758a.png)

Here's an export of the subflow.

```auto
[{"id":"fa1cba182af4c59b","type":"subflow","name":"writeLogMessage","info":"","category":"","in":[{"x":180,"y":180,"wires":[{"id":"f5777903346cf866"}]}],"out":[{"x":1040,"y":180,"wires":[{"id":"132992b4fc8fd735","port":0}]}],"env":[{"name":"subprocedureName","type":"str","value":""},{"name":"messageType","type":"num","value":""},{"name":"message","type":"str","value":""}],"meta":{},"color":"#C0DEED","icon":"node-red/db.svg"},{"id":"0edb2e0176656a33","type":"Stackhero-MySQL","z":"fa1cba182af4c59b","server":"","name":"insert_log","x":700,"y":180,"wires":[["132992b4fc8fd735"]]},{"id":"85c39fcb98799607","type":"function","z":"fa1cba182af4c59b","name":"set_query","func":"// create temporary object\nmsg.tmp = {};\n\n// move current topic to temporary location\nif (msg.topic)\n{\n msg.tmp.topic = msg.topic;\n}\n\n// move current payload to temporary location\nif (msg.payload)\n{\n msg.tmp.payload = msg.payload;\n}\n\nif (msg.log)\n{ \n // define query\n let sql = `CALL DB_22BS01.sp_write_execution_log(:procedureName, :procedureTimestamp, :subprocedureName, :messageType, :message);`;\n // define query parameters\n let sqlParameters = {\n procedureName: msg.log.procedureName,\n procedureTimestamp: msg.log.procedureTimestamp,\n subprocedureName: msg.log.subprocedureName,\n messageType: msg.log.messageType,\n message: msg.log.message\n };\n\n msg.topic = sql;\n msg.payload = sqlParameters;\n}\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":520,"y":180,"wires":[["0edb2e0176656a33"]]},{"id":"132992b4fc8fd735","type":"function","z":"fa1cba182af4c59b","name":"reset_msg","func":"\nif (msg.tmp)\n{\n // move tmp topic to current location\n if (msg.tmp.topic) {\n msg.topic = msg.tmp.topic;\n }\n\n // move tmp payload to current location\n if (msg.tmp.payload) {\n msg.payload = msg.tmp.payload;\n }\n\n delete msg.tmp;\n}\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":890,"y":180,"wires":[[]]},{"id":"f5777903346cf866","type":"function","z":"fa1cba182af4c59b","name":"set_log_obj","func":"\nif (msg.log)\n{\n delete msg.log;\n}\n\nmsg.log = {\n \"procedureName\": env.get(\"NR_FLOW_NAME\"),\n \"procedureTimestamp\": flow.get(\"$parent.procedureTimestamp\"),\n \"subprocedureName\": env.get(\"subprocedureName\"),\n \"messageType\": env.get(\"messageType\"),\n \"message\": env.get(\"message\")\n};\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":330,"y":180,"wires":[["85c39fcb98799607"]]},{"id":"35ca44cc6168a7df","type":"Stackhero-MySQL-Server","name":"","host":"","port":"","tls":false,"database":"","credentials":{}}]

```

Here's an example of how I would use it:

```auto
[{"id":"fa1cba182af4c59b","type":"subflow","name":"writeLogMessage","info":"","category":"","in":[{"x":180,"y":180,"wires":[{"id":"f5777903346cf866"}]}],"out":[{"x":1040,"y":180,"wires":[{"id":"132992b4fc8fd735","port":0}]}],"env":[{"name":"subprocedureName","type":"str","value":""},{"name":"messageType","type":"num","value":""},{"name":"message","type":"str","value":""}],"meta":{},"color":"#C0DEED","icon":"node-red/db.svg"},{"id":"0edb2e0176656a33","type":"Stackhero-MySQL","z":"fa1cba182af4c59b","server":"35ca44cc6168a7df","name":"insert_log","x":700,"y":180,"wires":[["132992b4fc8fd735"]]},{"id":"85c39fcb98799607","type":"function","z":"fa1cba182af4c59b","name":"set_query","func":"// create temporary object\nmsg.tmp = {};\n\n// move current topic to temporary location\nif (msg.topic)\n{\n msg.tmp.topic = msg.topic;\n}\n\n// move current payload to temporary location\nif (msg.payload)\n{\n msg.tmp.payload = msg.payload;\n}\n\nif (msg.log)\n{ \n // define query\n let sql = `CALL DB_22BS01.sp_write_execution_log(:procedureName, :procedureTimestamp, :subprocedureName, :messageType, :message);`;\n // define query parameters\n let sqlParameters = {\n procedureName: msg.log.procedureName,\n procedureTimestamp: msg.log.procedureTimestamp,\n subprocedureName: msg.log.subprocedureName,\n messageType: msg.log.messageType,\n message: msg.log.message\n };\n\n msg.topic = sql;\n msg.payload = sqlParameters;\n}\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":520,"y":180,"wires":[["0edb2e0176656a33"]]},{"id":"132992b4fc8fd735","type":"function","z":"fa1cba182af4c59b","name":"reset_msg","func":"\nif (msg.tmp)\n{\n // move tmp topic to current location\n if (msg.tmp.topic) {\n msg.topic = msg.tmp.topic;\n }\n\n // move tmp payload to current location\n if (msg.tmp.payload) {\n msg.payload = msg.tmp.payload;\n }\n\n delete msg.tmp;\n}\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":890,"y":180,"wires":[[]]},{"id":"f5777903346cf866","type":"function","z":"fa1cba182af4c59b","name":"set_log_obj","func":"\nif (msg.log)\n{\n delete msg.log;\n}\n\nmsg.log = {\n \"procedureName\": env.get(\"NR_FLOW_NAME\"),\n \"procedureTimestamp\": flow.get(\"$parent.procedureTimestamp\"),\n \"subprocedureName\": env.get(\"subprocedureName\"),\n \"messageType\": env.get(\"messageType\"),\n \"message\": env.get(\"message\")\n};\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":330,"y":180,"wires":[["85c39fcb98799607"]]},{"id":"35ca44cc6168a7df","type":"Stackhero-MySQL-Server","name":"db_22bs01","host":"localhost","port":"3306","tls":false,"database":"DB_22BS01"},{"id":"31e2b49952892852","type":"subflow:fa1cba182af4c59b","z":"180ebda9eb3fda15","name":"","env":[{"name":"subprocedureName","value":"test_sub_procedure","type":"str"},{"name":"messageType","value":"-4","type":"num"},{"name":"message","value":"this is a test. a: ${msg.test.a}","type":"env"},{"name":"procedureTimestamp","value":"currentTimestamp","type":"env"},{"name":"procedureName","value":"test","type":"str"},{"name":"subProcedureName","value":"sub_test","type":"str"}],"x":1000,"y":760,"wires":[["8fa6af7bca5968dd"]]},{"id":"401a3b0d576d74ee","type":"inject","z":"180ebda9eb3fda15","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"goodbye","payload":"hello","payloadType":"str","x":590,"y":760,"wires":[["33d8a1fc16b4adbc"]]},{"id":"8fa6af7bca5968dd","type":"debug","z":"180ebda9eb3fda15","name":"debug 4","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":1200,"y":760,"wires":[]},{"id":"33d8a1fc16b4adbc","type":"function","z":"180ebda9eb3fda15","name":"function 1","func":"\nflow.set(\"procedureTimestamp\", new Date());\n\nmsg.test = {\n a: 5\n};\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":800,"y":760,"wires":[["31e2b49952892852"]]}]

```

I would like to set the message parameter with a dynamic message and eventually inject the value of a msg or flow variable.  
I tried executing it with a static string and it works fine but I can't figure out how to dynamically inject values.

What would be the best way to achieve this?

Thanks in advance

---

<div class="post-metadata">

**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [29 May 2023 14:32 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786/2 "2023-05-29T14:32:00Z")

</div>

If I understand correctly you can use the or ||, so if msg.message is undefined or null then the env is used.  
e.g.

```auto
"message": msg.message || env.get("message")

```

---

<div class="post-metadata">

**Author:** ![elia-sysdesign](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/elia-sysdesign/32/80174_2.png) [@elia-sysdesign](https://discourse.nodered.org/u/elia-sysdesign)\
**Post date:** [29 May 2023 14:50 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786/3 "2023-05-29T14:50:42Z")

</div>

Hello @E1cid,

Thanks for the fast response.  
Unfortunately, that's not my problem.

If you look at the writeLogMessage instance, that is in the second exported flow of my first message, I'm trying to inject the value of **msg.test.a** into the **message** parameter:

```auto
this is a test. a: ${msg.test.a}

```

But this is what gets logged: `this is a test. a:`.

The variable is set in a function block before the writeLogMessage instance.

How do I inject the value of **msg.test.a** into my message parameter?

Thanks again

---

<div class="post-metadata">

**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [29 May 2023 15:10 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786/4 "2023-05-29T15:10:42Z")

</div>

If you enter it as a string then you could use a template node and mustache to reference the msg var, as a work around

```auto
[{"id":"fa1cba182af4c59b","type":"subflow","name":"writeLogMessage","info":"","category":"","in":[{"x":40,"y":180,"wires":[{"id":"745898d86faefe20"}]}],"out":[{"x":620,"y":200,"wires":[{"id":"132992b4fc8fd735","port":0}]}],"env":[{"name":"subprocedureName","type":"str","value":""},{"name":"messageType","type":"num","value":""},{"name":"message","type":"str","value":""}],"meta":{},"color":"#C0DEED","icon":"node-red/db.svg"},{"id":"132992b4fc8fd735","type":"function","z":"fa1cba182af4c59b","name":"reset_msg","func":"\nif (msg.tmp)\n{\n // move tmp topic to current location\n if (msg.tmp.topic) {\n msg.topic = msg.tmp.topic;\n }\n\n // move tmp payload to current location\n if (msg.tmp.payload) {\n msg.payload = msg.tmp.payload;\n }\n\n delete msg.tmp;\n}\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":490,"y":200,"wires":[[]]},{"id":"f5777903346cf866","type":"function","z":"fa1cba182af4c59b","name":"set_log_obj","func":"\nif (msg.log)\n{\n delete msg.log;\n}\n\nmsg.log = {\n \"procedureName\": env.get(\"NR_FLOW_NAME\"),\n \"procedureTimestamp\": flow.get(\"$parent.procedureTimestamp\"),\n \"subprocedureName\": env.get(\"subprocedureName\"),\n \"messageType\": env.get(\"messageType\"),\n \"message\": msg.message\n};\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":210,"y":180,"wires":[["132992b4fc8fd735"]]},{"id":"745898d86faefe20","type":"change","z":"fa1cba182af4c59b","name":"","rules":[{"t":"set","p":"template","pt":"msg","to":"message","tot":"env"}],"action":"","property":"","from":"","to":"","reg":false,"x":130,"y":80,"wires":[["66a1e2844b6ba7b7"]]},{"id":"66a1e2844b6ba7b7","type":"template","z":"fa1cba182af4c59b","name":"","field":"message","fieldType":"msg","format":"handlebars","syntax":"mustache","template":"","output":"str","x":300,"y":80,"wires":[["f5777903346cf866","ec70fe70fac4fb7b"]]},{"id":"ec70fe70fac4fb7b","type":"debug","z":"fa1cba182af4c59b","name":"debug 300","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":530,"y":60,"wires":[]},{"id":"401a3b0d576d74ee","type":"inject","z":"b9860b4b9de8c8da","name":"","props":[{"p":"payload"},{"p":"topic","vt":"str"}],"repeat":"","crontab":"","once":false,"onceDelay":0.1,"topic":"goodbye","payload":"hello","payloadType":"str","x":140,"y":3540,"wires":[["33d8a1fc16b4adbc"]]},{"id":"33d8a1fc16b4adbc","type":"function","z":"b9860b4b9de8c8da","name":"function 1","func":"\nflow.set(\"procedureTimestamp\", new Date());\n\nmsg.test = {\n a: 5\n};\n\nreturn msg;","outputs":1,"noerr":0,"initialize":"","finalize":"","libs":[],"x":350,"y":3540,"wires":[["31e2b49952892852"]]},{"id":"31e2b49952892852","type":"subflow:fa1cba182af4c59b","z":"b9860b4b9de8c8da","name":"","env":[{"name":"subprocedureName","value":"test_sub_procedure","type":"str"},{"name":"messageType","value":"-4","type":"num"},{"name":"message","value":"this is a test. a: {{test.a}}","type":"str"},{"name":"procedureTimestamp","value":"currentTimestamp","type":"env"},{"name":"procedureName","value":"test","type":"str"},{"name":"subProcedureName","value":"sub_test","type":"str"}],"x":550,"y":3540,"wires":[["8fa6af7bca5968dd"]]},{"id":"8fa6af7bca5968dd","type":"debug","z":"b9860b4b9de8c8da","name":"debug 4","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"true","targetType":"full","statusVal":"","statusType":"auto","x":750,"y":3540,"wires":[]}]

```

 ![chrome_screenshot_1685373175354](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/4/d/4d6a0479b4501848e721f22a459cec61e5ab73c4.png)

Removed mysql nodes so i could test.

---

<div class="post-metadata">

**Author:** ![elia-sysdesign](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/elia-sysdesign/32/80174_2.png) [@elia-sysdesign](https://discourse.nodered.org/u/elia-sysdesign)\
**Post date:** [29 May 2023 15:27 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786/5 "2023-05-29T15:27:54Z")

</div>

Thank you @E1cid!

Totally works!  
Cheers!

---

<div class="post-metadata">

**Author:** ![elia-sysdesign](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/elia-sysdesign/32/80174_2.png) [@elia-sysdesign](https://discourse.nodered.org/u/elia-sysdesign)\
**Post date:** [30 May 2023 07:18 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786/6 "2023-05-30T07:18:51Z")

</div>

Hello @E1cid again.

I have one last question.  
What if I want to print a whole object instead of a single variable.  
For example, I want to log the whole object **test** instead of **test.a**?

Thanks again.

---

<div class="post-metadata">

**Author:** ![E1cid](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/e1cid/32/77971_2.png) [@E1cid](https://discourse.nodered.org/u/E1cid)\
**Post date:** [30 May 2023 07:28 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786/7 "2023-05-30T07:28:39Z")

</div>

Then I would probably use a function instead of template. You would probably have to parse out the {{test}} section, then check type (string,number object etc) and deal with it accordingly, i.e convert test object to json string, then replace {{test}} with the string

---

<div class="post-metadata">

**Author:** ![elia-sysdesign](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/elia-sysdesign/32/80174_2.png) [@elia-sysdesign](https://discourse.nodered.org/u/elia-sysdesign)\
**Post date:** [30 May 2023 07:30 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786/8 "2023-05-30T07:30:32Z")

</div>

Ok @E1cid.

Thanks for the advice.

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [29 July 2023 07:30 UTC](https://discourse.nodered.org/t/referencing-msg-variable-in-environment-type-parameter/78786/9 "2023-07-29T07:30:57Z")

</div>

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