After further investigation, values are being set, but I'm still seeing some strange behavior.
I would have sworn that I was able to change setting from a web browser before with
http://zm/api/monitors/1.json -d "Monitor[Brightness]=30000". That's where I was seeing the error that was include in the original post. When I attempted to set values using curl, I was receiving a bunch of HTML and I assumed that it was the same error message. Upon closer inspection, it says that it has saved my values, however it is still giving an error message. Since I've always used a the "-s" curl directive, these errors may have been there all along.
So values are getting changed and they are being stored properly in mySql, however the values that show up in the zm console are different than the configured values. If I set Monitor[Brightness]=30000, zm console shows 29952. If I set it to 20000, zm shows 19968. I just noticed that same thing happens when I try to adjust the brightness in the zm console. If I set the brightness to 30000, as soon as I hit save, it changes to 29952.
Here is the response I get to: curl -XPUT
http://192.168.0.7/zm/api/monitors/1.json -d "Monitor[Brightness]=30000"
<pre class="cake-error"><a href="javascript:void(0);" onclick="document.getElementById('cakeErr5750385b863b5-trace').style.display = (document.getElementById('cakeErr5750385b863b5-trace').style.display == 'none' ? '' : 'none');"><b>Notice</b> (8)</a>: Undefined index: Type [<b>APP/Controller/MonitorsController.php</b>, line <b>242</b>]<div id="cakeErr5750385b863b5-trace" class="cake-stack-trace" style="display: none;"><a href="javascript:void(0);" onclick="document.getElementById('cakeErr5750385b863b5-code').style.display = (document.getElementById('cakeErr5750385b863b5-code').style.display == 'none' ? '' : 'none')">Code</a> <a href="javascript:void(0);" onclick="document.getElementById('cakeErr5750385b863b5-context').style.display = (document.getElementById('cakeErr5750385b863b5-context').style.display == 'none' ? '' : 'none')">Context</a><pre id="cakeErr5750385b863b5-code" class="cake-code-dump" style="display: none;"><code><span style="color: #000000"><span style="color: #0000BB"> </span><span style="color: #007700">}</span></span></code>
<code><span style="color: #000000"><span style="color: #0000BB"></span></span></code>
<span class="code-highlight"><code><span style="color: #000000"><span style="color: #0000BB"> </span><span style="color: #007700">if (</span><span style="color: #0000BB">$monitor</span><span style="color: #007700">[</span><span style="color: #DD0000">'Type'</span><span style="color: #007700">] == </span><span style="color: #DD0000">'Local'</span><span style="color: #007700">) {</span></span></code></span></pre><pre id="cakeErr5750385b863b5-context" class="cake-context" style="display: none;">$id = '1'
$command = 'restart'
$monitor = array(
'Monitor' => array(
'Brightness' => '30000'
)
)
$daemon = null
$args = ''
$daemons = array()</pre><pre class="stack-trace">MonitorsController::daemonControl() - APP/Controller/MonitorsController.php, line 242
MonitorsController::edit() - APP/Controller/MonitorsController.php, line 141
ReflectionMethod::invokeArgs() - [internal], line ??
Controller::invokeAction() - CORE/Cake/Controller/Controller.php, line 490
AppController::invokeAction() - APP/Plugin/Crud/Lib/CrudControllerTrait.php, line 31
Dispatcher::_invoke() - CORE/Cake/Routing/Dispatcher.php, line 191
Dispatcher::dispatch() - CORE/Cake/Routing/Dispatcher.php, line 165
[main] - APP/webroot/index.php, line 108</pre></div></pre><pre class="cake-error"><a href="javascript:void(0);" onclick="document.getElementById('cakeErr5750385b86b3b-trace').style.display = (document.getElementById('cakeErr5750385b86b3b-trace').style.display == 'none' ? '' : 'none');"><b>Notice</b> (8)</a>: Undefined index: Function [<b>APP/Controller/MonitorsController.php</b>, line <b>248</b>]<div id="cakeErr5750385b86b3b-trace" class="cake-stack-trace" style="display: none;"><a href="javascript:void(0);" onclick="document.getElementById('cakeErr5750385b86b3b-code').style.display = (document.getElementById('cakeErr5750385b86b3b-code').style.display == 'none' ? '' : 'none')">Code</a> <a href="javascript:void(0);" onclick="document.getElementById('cakeErr5750385b86b3b-context').style.display = (document.getElementById('cakeErr5750385b86b3b-context').style.display == 'none' ? '' : 'none')">Context</a><pre id="cakeErr5750385b86b3b-code" class="cake-code-dump" style="display: none;"><code><span style="color: #000000"><span style="color: #0000BB"> </span><span style="color: #007700">}</span></span></code>
<code><span style="color: #000000"><span style="color: #0000BB"></span></span></code>
<span class="code-highlight"><code><span style="color: #000000"><span style="color: #0000BB"> </span><span style="color: #007700">if (</span><span style="color: #0000BB">$monitor</span><span style="color: #007700">[</span><span style="color: #DD0000">'Function'</span><span style="color: #007700">] == </span><span style="color: #DD0000">'Monitor'</span><span style="color: #007700">) {</span></span></code></span></pre><pre id="cakeErr5750385b86b3b-context" class="cake-context" style="display: none;">$id = '1'
$command = 'restart'
$monitor = array(
'Monitor' => array(
'Brightness' => '30000'
)
)
$daemon = null
$args = '-m 1'
$daemons = array()</pre><pre class="stack-trace">MonitorsController::daemonControl() - APP/Controller/MonitorsController.php, line 248
MonitorsController::edit() - APP/Controller/MonitorsController.php, line 141
ReflectionMethod::invokeArgs() - [internal], line ??
Controller::invokeAction() - CORE/Cake/Controller/Controller.php, line 490
AppController::invokeAction() - APP/Plugin/Crud/Lib/CrudControllerTrait.php, line 31
Dispatcher::_invoke() - CORE/Cake/Routing/Dispatcher.php, line 191
Dispatcher::dispatch() - CORE/Cake/Routing/Dispatcher.php, line 165
[main] - APP/webroot/index.php, line 108</pre></div></pre>{
"message": "Saved"
}