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Collins Ruto
Collins Ruto

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Send a HashMap as parameters to a rust smart contract

To send a HashMap as a parameter to a Rust function from the near-cli, you can use the --arg flag to specify the key-value pairs of the map as command-line arguments. The --arg flag takes two arguments: the key and the value, separated by a = sign.

For example, suppose you have a Rust function named my_function that takes a HashMap<String, String> as an argument. You could call this function from the near-cli using the following command:

near call <contract_name> my_function --arg key1=value1 --arg key2=value2

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This would pass a HashMap with two entries to the my_function function, where the keys are "key1" and "key2", and the corresponding values are "value1" and "value2", respectively.

Inside the my_function function, you can access the HashMap argument using the std::env::args method, which returns an iterator over the command-line arguments passed to the function. You can then use the Iterator::filter method to filter the arguments for those with the --arg flag, and the Iterator::map method to map each argument to a tuple containing the key and value. Finally, you can use the Iterator::collect method to collect the tuples into a HashMap:

use std::collections::HashMap;
use std::env;

fn my_function(map: HashMap<String, String>) {
    // function body goes here

impl MyContract {
    pub fn call_my_function() {
        let args: Vec<String> = env::args().collect();
        let map: HashMap<String, String> = args
            .filter(|arg| arg.starts_with("--arg"))
            .map(|arg| arg.split("=").collect::<Vec<&str>>())
            .map(|parts| (parts[0].to_string(), parts[1].to_string()))


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I hope this helps! Let me know if you have any other questions.

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