Update shared image attribute

Who it’s for

Anyone who needs a picture attached to an entity and updated from the dashboard — a site photo on an asset, a wiring diagram on a device, a product image on a piece of equipment. The image belongs to the entity and should be changed by whoever maintains the entity, not by an administrator.

What it does

The Update shared image attribute widget presents a single image field bound to a shared attribute key, showing the current image and letting a new one be applied or discarded. The image is stored on the entity as a shared attribute, so the device receives it on its next connection, which suits an image the firmware itself uses.

• One image, one key — a focused form rather than a general attribute editor.
• The current image is previewed, so the person changing it can see what is there before replacing it.
• Apply and discard are explicit, so a picture selected by mistake does not overwrite the stored one.
• A clear button can be shown for removing the image entirely rather than replacing it.
• A result message confirms the write, which matters because an image field gives little other feedback.
• The Update shared image attribute widget writes one attribute: several images per entity need several widgets, each bound to its own key.

How to set up

Data keys

The Update shared image attribute widget writes the attribute key configured on its datasource.

Attribute	Scope	Operation	Description
Configured key	Shared	Read + Write	The image is stored as a base64 string. The widget reads the current value to show the preview and writes the new one on apply.

Configure the key on the datasource before anything else, and check the scope matches what will read the image. A picture written to shared scope is only useful to whatever actually reads shared attributes.

Form

Setting	Default	Effect
Display preview	On	Shows the current image above the field
Display apply button	On	Requires an explicit action to write the new image
Display discard button	On	Lets a selection be abandoned before writing
Display clear button	Off	Adds a button that removes the stored image
Show result message	On	Confirms the write on screen
Widget title	Platform default	The caption above the form

How to customize

• To let the image be removed — turn on Display clear button, which is separate from replacing it.
• To simplify a guided form — turn off Display discard button where cancelling is handled elsewhere on the page.
• To save space — turn off Display preview on a compact panel, accepting that the person cannot see what they are replacing.
• To reduce noise on a busy dashboard — turn off Show result message.
• To caption the form — set the Widget title to name the image being maintained.

Tips

• Keep the preview on wherever an image can be overwritten. Without it the form gives no indication that a picture is already stored, and the first sign of a mistake is the old image being gone.
• Watch the size of what is uploaded. The image is stored inline as base64 on the entity rather than as a file reference, so a full-resolution photograph is a large attribute that is then read on every dashboard load.