Polygerrit plugin does not always show a changeAction button - gerrit

Question

I am writing a plugin for gerrit 2.16.12 that should show a button for starting an extended build stage on our Jenkins for a particular change. My problems are two.
It seems that to show the button I need to reload the page once. If I go back to the page later, I still need to do a reload.
If I press the action, the plugin shows a popup with some values filled in. From there I can submit the build with the parameters needed. But if I press the button a second time, the values are not filled in and the submit button in the form does not work.
Perhaps they are related, not sure. Any ideas?
This is my plugin html file:
<dom-module id="build-all-stages">
<script>
//alert("Gerrit plugin is being installed");
console.log("Loading build-all-stages plugin");
Gerrit.install(plugin => {
changeActions = plugin.changeActions();
key = changeActions.add(changeActions.ActionType.CHANGE, 'Build All Stages');
changeActions.addTapListener(key, ev => {
plugin.popup("build-all-stages-mod").then(popup => {
el = document.querySelector('gr-change-metadata');
if (el == null) {
alert("Could not find the gr-change-metadata element");
popup.close();
return;
}
change = el.change;
revision = el.revision;
bast = document.querySelector('build-all-stages-mod');
if (bast == null) {
alert("Could not find the plugin element.");
popup.close();
return;
}
bast.addEventListener('done', () => {
console.log("Closing popup");
popup.close();
});
bast.gerrit_project = change.project;
bast.gerrit_branch = change.branch;
bast.gerrit_newrev = change.branch;
bast.gerrit_refname = change.branch;
bast.gerrit_refspec = revision.ref;
bast.gerrit_patchset_revision = revision.commit.commit;
});
});
});
console.log("Loaded build-all-stages plugin");
</script>
</dom-module>
<dom-module id="build-all-stages-mod">
<template>
<h2>Build all stages in Jenkins</h2>
Please make sure that you are allready logged in to Jenkins and then verify the values below pefore pressing submit:
<form id="jenkins_form"
method="post"
on-submit="handleDone"
target="_blank"
action="https://jenkins.mycompany.com/job/[[gerrit_branch]]/job/Stage0-All_pipeline_stages-Test/buildWithParameters">
<table>
<tr><td>GERRIT_PROJECT: </td><td> <input name="GERRIT_PROJECT" size=40 value="[[gerrit_project]]"/></td></tr>
<tr><td>GERRIT_BRANCH: </td><td> <input name="GERRIT_BRANCH" size=40 value="[[gerrit_branch]]"/></td></tr>
<tr><td>GERRIT_NEWREV: </td><td> <input name="GERRIT_NEWREV" size=40 value="[[gerrit_newrev]]"/></td></tr>
<tr><td>GERRIT_REFNAME: </td><td> <input name="GERRIT_REFNAME" size=40 value="[[gerrit_refname]]"/></td></tr>
<tr><td>GERRIT_REFSPEC: </td><td> <input name="GERRIT_REFSPEC" size=40 value="[[gerrit_refspec]]"/></td></tr>
<tr><td>GERRIT_PATCHSET_REVISION: </td><td> <input name="GERRIT_PATCHSET_REVISION" size=40 value="[[gerrit_patchset_revision]]"/></td></tr>
</table>
<input name="userFlag" value="true" type="hidden"/>
<button type="submit" value="Submit">Submit</button>
<button id="jenkins_cancel" type="button" on-click="handleDone">Cancel</button>
</form>
</template>
<style>
:host {
display: block;
border: 1px solid black;
padding: 5px;
}
td {
padding: 3px;
}
</style>
<script>
gerrit_type = {
type: String,
value: "",
notify: false,
reflectToAttribute: true
};
gerrit_type = String;
Polymer({
is: 'build-all-stages-mod',
properties: {
gerrit_project: gerrit_type,
gerrit_branch: gerrit_type,
gerrit_newrev: gerrit_type,
gerrit_refname: gerrit_type,
gerrit_refspec: gerrit_type,
gerrit_patchset_revision: gerrit_type,
},
handleDone: function() {
this.fire('done', null);
}
});
</script>

Answer 1

The plugin should listen to the showChange event so the button will display automatically.
Gerrit.install(plugin => {
plugin.on('showchange', params => {
console.log(params)
const changeActions = plugin.changeActions();
changeActions.add('revision', 'display name');
//...
}
}