Attachments

While attributes are taken from each feature itself in a layer, an attachment is a file that is stored somewhere else but can be treated as an attribute. An attachment is typically an image or document that relates to a special feature and for practical reasons can not be stored in an attribute. Attachments can be viewed, added and removed by the user in the editor form and viewed in featureInfo as links or emedded as images.

Attachments are configured on each layer. It can be configured for both raster and vector layers, but can only be edited on vector layers. In order to use attachments, an attachment server is needed. The attachment server must implement the arcgis server rest api for attachments.

• attachment Infos https://developers.arcgis.com/rest/services-reference/enterprise/attachment-infos-feature-service-.htm
• attachment https://developers.arcgis.com/rest/services-reference/enterprise/attachment-feature-service-.htm
• add attachment https://developers.arcgis.com/rest/services-reference/enterprise/add-attachment.htm
• delete attachment https://developers.arcgis.com/rest/services-reference/enterprise/delete-attachments.htm

Optionally the server can extend the AGS interface by adding the concept of attachment groups in order to group attachments in different groups. Groups can be used to have different rules and display them differently. AGS server can be used out-of-the-box for AGS layers, but the extented format must be implemented as a server side component.

The extensions to the AGS format are:

• The response from attachments infos must include a "group" property for each attachmentInfo object
• The request to addAttachment must include a "group" parameter

A reference implementation of the extended format is available here: https://github.com/ornskoldsvikskommun/attachmentServer-reference It should not be used for production environments as it lacks security, performance and flexibilty.

Attachment configuration

Attachments are configured on each layer using the "attachments" property containing an object with the following properties.

Property	Description	Required	Default value
url	The base adress for the attachment server.	Yes
formTitle	Title of section in editor form	No	'Bilagor'
format	The format to use. 'origo' or 'arcgis'. 'origo' extenteds the AGS format by using groups	No	'origo'
foreignKey	Name of the attribute in the parent feature that contains the private key.	No	Uses id of feature
stripLayerNameFromId	Removes layer name from featureid when foreignKey is not specified. Useful when using geoserver wfs services to get only database FID as private key.	No	true
layerId	The layer id in the attachment server.	No	Layer name
groups	Array of group objects defining an attachment group. A group has its own title and each group is treated as a separate attribute. At least one group has to be specified. If format is "arcgis" exactly one group must be specified	Yes

Group object

Property	Description	Required	Default value
name	Name of the group on the attachment server. Ignored for format 'arcgis'	Yes
title	Title displayed in the editor. Ignored for format 'arcgis'	No	name
linkAttribute	Name of an attribute to create on a feature containing all links as a semicolon separated list. Can be used to create links in featureInfo using the img or url property.	No
fileNameAttribute	Name of an attribute to create on a feature containing all filename as a semicolon separated list. Order is same as linkAttribute list. Can be used in combination with linkAttribute to set link text using the linktext property	No
allowedFiles	Comma separated list of valid file extensions and mime types that are allowed to upload. Format is accordning to the accept attribute of https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/file	No	*

Example attachment configuration

"attachments": {
        "formTitle" : "Attachments",
        "layerId": "entity_blob",
        "url": "http://gis.kommun.org/attachmentserver/",
        "groups": [
          {
            "name": "proto",
            "title": "Protocols",
            "allowedFiles": ".pdf"
          },
          {
            "name": "public",
            "title": "Public Image",
            "allowedFiles": ".jpg,.png",
            "linkAttribute": "pictureLinks",
            "fileNameAttribute": "pictureTexts"

          }
        ]
      }

Example display attachments in featureinfo configuration

"attributes": [
    {
        "title": "Images",
        "linktext": "pictureTexts",
        "url": "pictureLinks",
        "splitter": ";"
     }
]