process to get a property from an object

[soxofaan]

Use case: user defines a user defined process with aspatial_extent parameter with the "bounding box" schema like

openeo-processes/meta/subtype-schemas.json

Lines 13 to 70 in 6141771

	"bounding-box": {
	"type": "object",
	"subtype": "bounding-box",
	"title": "Bounding Box",
	"description": "A bounding box with the required fields `west`, `south`, `east`, `north` and optionally `base`, `height`, `crs`. The `crs` is a EPSG code or a WKT2:2018 string.",
	"required": [
	"west",
	"south",
	"east",
	"north"
	],
	"properties": {
	"west": {
	"description": "West (lower left corner, coordinate axis 1).",
	"type": "number"
	},
	"south": {
	"description": "South (lower left corner, coordinate axis 2).",
	"type": "number"
	},
	"east": {
	"description": "East (upper right corner, coordinate axis 1).",
	"type": "number"
	},
	"north": {
	"description": "North (upper right corner, coordinate axis 2).",
	"type": "number"
	},
	"base": {
	"description": "Base (optional, lower left corner, coordinate axis 3).",
	"type": [
	"number",
	"null"
	],
	"default": null
	},
	"height": {
	"description": "Height (optional, upper right corner, coordinate axis 3).",
	"type": [
	"number",
	"null"
	],
	"default": null
	},
	"crs": {
	"description": "Coordinate reference system of the extent, specified as as [EPSG code](http://www.epsg-registry.org/) or [WKT2 CRS string](http://docs.opengeospatial.org/is/18-010r7/18-010r7.html). Defaults to `4326` (EPSG code 4326) unless the client explicitly requests a different coordinate reference system.",
	"anyOf": [
	{
	"$ref": "#/definitions/epsg-code"
	},
	{
	"$ref": "#/definitions/wkt2-definition"
	}
	],
	"default": 4326
	}
	}
	},

How to extract, for example, the "crs" property from that object in a process graph, e.g. to be able to pass it through context to a UDF?

array_element with argument label="crs" comes to mind, but the value of the parameter is an object, not an array, so that's technically not valid.

Would it make sense to expand the scope of array_element to objects? Or would it be cleaner to add some kind of new process, e.g. object_property(object data, string property): any?

[m-mohr]

Yes, that's something that I was thinking about for a long time already. I think we should add such a process. It also comes with a number of other operations potentially, similar to array_create and array_modify.