For working in Rental App is possible to add Items as rent item, which you have in storages. Not all of them are intended for rent and thats the reason why you have ability to create Item before creating Rent Item. For more information about creating Rent Item, see How to create Rent Item.
Go to Search and enter Items.
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Note:
In case you want to rent this item, the field Rent Item situated in section Inventory must be turned on. If it's turned off, the Item can not be rented! In case when Rent Item Created is turned on, it means that rent item is already created from this item.
Note:
If we change “Blocked” to YES on the Item level, the Boolean “Rent Item” is changed to NO and the “Rent item” button will be manually not possible to edit unless the user changes the blocked value to NO. If item is not blocked, the user can decide whether the rent item value will be YES or NO.
Follow up:
How to do basic setup of OneCore Rental App
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