Channel Form: Unexpected default value behavior as placeholder

[oxzi]

Describing a channel holding a configuration option with a non empty default field results in this default being rendered as the input's placeholder (<input placeholder="…">). However, when creating or editing this channel through web, this placeholder value will not be reflected in the database and is not used as a default.

As a concrete example, let's start with the following Go snippet:

func (ch *Webhook) GetInfo() *plugin.Info {
	elements := []*plugin.ConfigOption{
		// [ . . . ]
		{
			Name: "request_body_template",
			Type: "string",
			Label: map[string]string{
				"en_US": "Request Body Template",
				"de_DE": "Anfragedaten-Template",
			},
			Help: map[string]string{
				"en_US": "Go template applied to the current plugin.NotificationRequest to create an request body.",
				"de_DE": "Go-Template über das zu verarbeitende plugin.NotificationRequest zum Erzeugen der mitgesendeten Anfragedaten.",
			},
			// Default as a minimal working example to send a JSON object.
			Default: `{"id": {{.Incident.Id}}, "type": "{{.Event.Type}}", "name": "{{.Object.Name}}", "severity": "{{.Incident.Severity}}", "url": "{{.Incident.Url}}"}`,
		},
	}

	// [ . . . ]
}

This results in the following available_channel_type entry:

notifications=# select config_attrs from available_channel_type where type = 'webhook';
-[ RECORD 1 ]-
config_attrs | [{…},{"name":"request_body_template","type":"string","label":{"de_DE":"Anfragedaten-Template","en_US":"Request Body Template"},"help":{"de_DE":"Go-Template über das zu verarbeitende plugin.NotificationRequest zum Erzeugen der mitgesendeten Anfragedaten.","en_US":"Go template applied to the current plugin.NotificationRequest to create an request body."},"default":"{\"id\": {{.Incident.Id}}, \"type\": \"{{.Event.Type}}\", \"name\": \"{{.Object.Name}}\", \"severity\": \"{{.Incident.Severity}}\", \"url\": \"{{.Incident.Url}}\"}","min":null,"max":null}]

Within the web, the following output will be generated:

<div class="control-group">
  <div class="control-label-group">
    <label>Request Body Template</label>
  </div>
  <input placeholder="{&quot;id&quot;: {{.Incident.Id}}, &quot;type&quot;: &quot;{{.Event.Type}}&quot;, &quot;name&quot;: &quot;{{.Object.Name}}&quot;, &quot;severity&quot;: &quot;{{.Incident.Severity}}&quot;, &quot;url&quot;: &quot;{{.Incident.Url}}&quot;}" name="config[request_body_template]" type="text">
  <i class="icon fa-info-circle control-info fa" role="image" title="Go template applied to the current plugin.NotificationRequest to create an request body."></i>
</div>

However, when now saving this entry with the placeholder value, it will be written as null to the database:

notifications=# select * from channel;
-[ RECORD 1 ]-------------------------------------------------------------------------------------------------------
id     | 1
name   | web
type   | webhook
config | {"method":"POST","url_template":"http:\/\/http-echo:8000\/{{.Incident.Id}}\/","request_body_template":null}

I would expect a default named field to create a default value which will be used when no other value was entered.

[nilmerg]

The reason for this behavior is that a default may change. If a default is stored that way, it never changes automatically. If the default is not applied by the channel plugin, this needs to be fixed.

[oxzi]

The reason for this behavior is that a default may change. If a default is stored that way, it never changes automatically. If the default is not applied by the channel plugin, this needs to be fixed.

Fair enough. But then it should be reflected in the database that the default value should be used. This would also bring up the question how to distinct an empty or null value from the wish to use the default.

[nilmerg]

Usually, a non existing value for a config option means to use the default. In this case, NULL. But yeah, it is currently not possible to store e.g. the empty string. We could of course change this, so that the default is not a placeholder, but is just not stored if not adjusted.

[oxzi]

As I just stumbled about this again: configuring a Default results in populating the input's placeholder field, but one has to manually type the value again in the web dialog when Required: true.

This is a bit frustrating, as I am unable to catch this on the backend by replacing an empty value to the configured default because the web dialog forbids submitting an empty form. However, when I starts typing, the shown placeholder disappears.

[nilmerg]

Have you seen Icinga/icinga-notifications#172?

[oxzi]

Have you seen Icinga/icinga-notifications#172?

Now I've seen it. It kinda addresses this very issue.