Upgrades

In Dojo, all models are upgradeable, which means that when their code changes, they are redeployed to the same address, preserving the existing model storage and therefore the existing model data.

However, to be able to preserve existing model data, there are some limitations.

General rules

• To be upgradeable, the layout of a model must not be packed (using IntrospectPacked).

• For composite data structures like struct, enum, tuple and array

  • they are upgreadable as soon as all their elements are upgreadable,
  • existing elements cannot be removed, they can only be modified according to the rules described on this page. New elements can be freely added.

• Each element of a data structure must keep the same type (i.e a tuple must remain a tuple), the same name and the same attributes if any (such as #[key] for model members).

• A primitive type can be upgraded to a larger primitive type as soon as its felt252 representation uses the same number of felts (for example, u8 to u128 but not u128 to u256). See the next chapter for more details.

• A key model member is upgradeable only if its type is an upgreadable primitive or an enum with new variants only (existing variants cannot be modified for a key member).

Primitive upgrades

This table lists the allowed upgrades for every primitive types. The type usize is not supported since it is a architecture-dependent type.