Is there a function in Solidity to load data, i.e a .txt or .csv, into a smart contract

Question

This is a pretty basic question, I'm looking for a function that will load data from either a .txt or .csv file. I have found the import function but when I tried using this I'm getting an error message.

Answer 1

The answer "no". Solidity cannot handle "txt" or "csv" files directly. In fact, at runtime, all there is the blockchain state. Solidity cannot communicate with the external world (not even via the HTTP protocol).

If you want to load data into your contract, you should encode it using a dynamic-length type such as bytes, then ABI decode it.

Answer 2

It is impossible, as worded, in principle.

To elaborate, the blockchain principle requires that all nodes must be able reconstruct the blockchain state from transactions now, and any time in the future. This implies certain limitations.

• functions must be deterministic, so transactions are deterministic
• no external input is possible, except ...
• the only acceptable input is data signed by an externally owned account.

Therefore, if you want to load data into the contract, the usual approach would be to construct a function that accepts input possibly from a privileged user. Parse the CSV etc. on the client side. The client would sign and send elements of the CSV to a function that accepts the input. The contract would be unconcerned with how the client determined what to sign.

Such a procedure could be part of a migration process.

Hope it helps.