Why Is "target" an Array? - sapui5

Question

I have the following route definition:
"routes": [{
"name": "overview",
"pattern": "",
"target": [
"overview"
]
}, {
"name": "customers",
"pattern": "/customers",
"target": [
"customers"
]
}, {
"name": "customer",
"pattern": "/customer/{id}",
"target": [
"customer"
]
}],
Why does the target property expect an array?

Answer 1

The value of the target property can be an array but it doesn't have to be, as stated in the API reference of sap.ui.core.Route:
The reason why it can await an array at all, is to support displaying multiple view (target) instances at once when navigating to a single route / navigating based on a certain hash value.
Source: Routing and Navigation
Example: The app is based on the Flexible Column Layout (formerly "Split-Screen" layout with sap.m.SplitApp) and the user visits it via a deep link having the hash value already e.g. #/Objects/ObjectID_14.
Source code
In this case, if only a single target name were assigned to the target property, only one of the views would have been able to be displayed. The target property can, however, contain multiple target names which will be then resolved and put based on the controlAggregation accordingly.
"routes": [
{
"name": "masterDetail",
"pattern": "Objects/{objectId}",
"target": [
"master",
"detail"
]
}
],
"targets": {
"master": {
"name": "Master",
"controlAggregation": "beginColumnPages"
},
"detail": {
"name": "Detail",
"controlAggregation": "midColumnPages"
}
}
To learn more about routing, please follow these steps: https://ui5.sap.com/#/topic/1b6dcd39a6a74f528b27ddb22f15af0d

Answer 2

Because a route could have multiple targets. This is the equivalent of the former subroutes.
By using multiple targets for a single route you can update different areas of your application at the same time resp. based on the same routing pattern.
Think of a SplitApp. If you want to change as well Master and Detail view based on routing you can define both of them as targets of the same route.
Find more info in the docs: https://sapui5.hana.ondemand.com/#/topic/b01840ec42ef48e6bfd2bc12612f501f