Related Layers

A related layer is a layer that is a child in a 1-to-many relationship. Origo supports related layers for WFS layers by defining a private-foreign key relation between layers. The layers do not have to be in the same database or be servered from the same WFS server. The relation is only stored in the child object, which makes it suitable for adding attributes to a table that is considered read only. A layer can have several child layers and a child layer can have child layers of its own.

Entries in the child layer can be added, deleted and edited through the parent's edit form and does not have a geometry of its own. Child objects may have a geometry, but there is not support to edit or add new geometries other that edit the child layer directly.

Attributes from child layers can be aggregated and displayed in the featureInfo window of the parent.

Related layers Configuration

All configuration regarding the relation is performed on the parent layer. The child layer must be configured as an ordinary wfs layer and most likely configured with 'isTable': true. The child layer can use 'strategy': 'bbox' even if it is a table. In that case related objects are fetched when the parent is edited or featureInfo is displayed

Relations are configured on the parent layer using the "relatedLayers" property containing an array of objects with the following properties.

Property	Description	Required	Default value
layerName	Name of the child layer as already configured as a layer	Yes
PK	Name of the field that holds the private key in the parent object.	No	featureid (omit for featureid as that can not be explicitly set)
stripPK	If PK is featureid, remove layer name part from featureid when joining. Useful to keep only the fid part as FK in the database.	No	true
FK	Name of field in child that holds the foreign key. When a new entry is created this field will be updated with the value of PK of the parent.	Yes
FKIsString	Has to be true if the FK field datatype in database is string.	No	false
childTitle	The title (string) that will be displayed above all child elements in the parent's attributes editor	No	Child layer's title
featureTitle	Name of the attribute that holds the text that will be displayed in the parent's attribute form for each feature	No	featureid
maxChildren	Number of children that can be added.	No	Unlimited
cascadingDelete	How to handle if parent is deleted. Can be one of 'cascade' : delete recursively, both in database and in local layer. 'db': Assume database has cascading delete and only recursively delete locally. 'none': Do nothing. Child remains both locally and in db, orphaned	No	'none'
disableAdd	true if the add button in the parent's edit form should be disabled for this layer	No	false
disableDelete	true if the delete button in the parent's edit form should be disabled for this layer	No	false
disableEdit	true if the edit button in the parent's edit form should be disabled for this layer	No	false
promoteAttribs	An array of promoteAttrib objects that defines how attributes are aggregated and available to the parent in featureInfo	No	None

promoteAttrib object

Each entry creates an attribute on the parent by first extract an expression from each child and then aggregate the result from all children. Currently the only supported aggregation function is string.join()

Property	Description	Required	Default value
parentName	Name of the attribute to create in the parent	Yes
html	Template string that extracts values from each child object. Attribute names enclosed in {{}} are replaced with its value. Does not have to be html, but can contain html tags	Yes
separator	String to use as separator when aggregating extracted strings	No	Empty string

Example related tables configuration

Basic example to set up a parent which has a related child layer. The parent itself is not editable, but the child layer has two attributes that can be edited. Also the attributes from the child layer is aggregated and displayed in the featureInfo window of the parent.

{
  "layers": [
    {
      // This is the child layer
      "name": "sf:person",
      "source": "local_wfs",
      "type": "WFS",
      "isTable": true,
      "attributes": [
        {
          "name": "name",
          "type": "text"
        },
        {
          "name": "org",
          "type": "text"
        }
      ]
    },
    {
      // This is the parent layer
      "name": "sf:property",
      "queryable": true,
      "group": "root",
      "source": "local_wfs",
      "type": "WFS",
      "geometryName": "the_geom",
      "geometryType": "Point",
      "visible": true,
      "editable": true,
      "allowedEditOperations": [
        "updateAttributes"
      ],
      "attributes": [
        {
          "name": "adress",
          "type": "text",
          "readonly": true
        },
        {
          // This is the temporary attribute created by related table configuration
          "name": "responsible",
        }
      ],
      "relatedLayers": [
        {
          "layerName": "person",
          "FK": "parent_fid",
          "featureTitle": "name",
          "promoteAttribs": [
            {
              "parentName": "responsible",
              "html": "<p><b>{{name}},</b>{{org}}</p>"
            }
          ]
        }
      ]
    }
  ]
}