Getting all data from a LookupMap

[blackghost1987]

I read in the documentation that LookupMap doesn't support iteration, which is fine, I guess this is the price of being efficient. But is there no way at all to get the stored data from a LookupMap?

I'm trying to update some data stored in a LookupMap, but I can only reach data by using a specific key. What about contract storage migrations? How would you migrate a LookupMap to something else? I tried to change it's type via a migration to something that supports iteration (e.g. TreeMap), but again, to move every value from the old collection to the new one, I need to iterate through it...

I thought about getting and inserting the values one by one, but there's no way to get the existing keys either 😢 As a last resort I even thought about iterating through the whole key-space, but the key is unfortunately a Vec<u8>, so there are infinite possible keys.

Is there a workaround for this? Can I get the raw data somehow from the underlying storage?

[willemneal]

Currently there is a near-cli command (and RPC method) to get the state of a contract from a prefix: https://github.com/near/near-cli/blob/master/commands/view-state.js

However, this suffers from a configuration for NEAR nodes that limits this to contracts with state less than 50 kb if remember correctly, so likely won't work.

I haven't tried, but there are now other RPC providers which might lossen that requirement or per happens with the dev console where Pagoda requires you to provide an API key.

[blackghost1987]

Thanks for the response, that could be a workaround, but I'm looking for a programattical way to access the data from the smart contract code

[willemneal]

Without an unordered or tree map, there is no way to iterate from within the contract. So you would need to get the keys with the method above and then have a migrate function that takes sets of keys and writes the data to a new iterable collection.