# How to Attach Multiple Photos to Features

TIP

To see this setup in practice, clone the following project: Mergin Maps Project documentation/forms_multiple_photos documentation/forms_multiple_photos (opens new window).

To link multiple photos to a single feature, we need a unique field to link following tables:

DANGER

Do not use the FID field to link these tables. FIDs can be changed during synchronisation, which can result in having photos linked to the incorrect feature. You can learn more about synchronisation in Behind Data Synchronisation.

To create 1:N relation between these tables correctly, you need to:

  1. Create a new text field in the survey layer.
    uuid
  2. Use the uuid() as the default value for this field. This assigns a unique identifier to every created feature, even when different surveyors create features simultaneously.
    uuid
  3. Create a new text field in the non-spatial table that will be used to store the UUID of features from the survey layer (the foreign key).
  4. Configure 1:N relation in the QGIS project:

Mergin Maps Input detects the type of 1-N relation and uses the Attachment widget to display the image viewer for the relations.

Many photos to a single feature