Native Layer Developer Guides

Learn more about developing DApps on the Native Layer:

• Introduction to Spring

• Developing Smart Contracts on the Native Layer

• Interacting with Smart Contracts via SDK

• Interacting with exSat via RESTful API

Read data from contracts

exSat native layer stores data in tables, which are similar to database tables. Each table has a name and a set of fields. Tables are organized into scopes, which are defined by the smart contract that created the table.

To retrieve data from a table, you need to know its name, scope, and the name of the smart contract that created it. You can also specify a lower and upper bound to limit the amount of data returned.

To retrive data from a exSat native contract, all you need is :

• A command-line interface to run curl commands.

• Access to an exSat native layer RPC node. You could get the public RPC node here, or build your own RPC node.

• The name of the contract, the table name, scope, and maybe the indexes.

use "get_table_rows" to get data from contract

The get_table_rows function retrieves rows from a table. It takes the following parameters in JSON format:

code	must	string The name of the smart contract that controls the provided table
table	must	string The name of the table to query
scope	must	string The account to which this data belongs
index_position	optional	string Position of the index used, accepted parameters primary, secondary, tertiary, fourth, fifth, sixth, seventh, eighth, ninth , tenth
key_type	optional	string Type of key specified by index_position (for example - uint64_t or name)
encode_type	optional	string representing the encoded type of the key_type parameter, either dec or hex, defaults to dec.
lower_bound	optional	string Filters results to return the first element that is not less than provided value in set
upper_bound	optional	string Filters results to return the first element that is greater than provided value in set
limit	optional	integer <int32>Default: 10 Limit number of results returned.
reverse	optional	boolean Default: false Reverse the order of returned results
show_payer	optional	boolean Default: false Show RAM payer

Below is an example that retrieves rows from validators table, owned by the endrmng.xsat account and having endrmng.xsat as scope. which aims to get the registration information of the first validator.

curl --request POST \
--url https://rpc-sg.exsat.network/v1/chain/get_table_rows \
--header 'content-type: application/json'  \
--data '{ 
"json": true, 
"code": "endrmng.xsat", 
"scope": "endrmng.xsat", 
"table": "validators", 
"lower_bound": "0", 
"limit": 1, 
"reverse": false 
}'

In the example above:

• The rows values are returned as JSON, set by the json parameter.

• The table is owned by the account endrmng.xsat, set by the code parameter.

• The table scope is endrmng.xsat, set by the scope parameter.

• The table name is validators, set by the table parameter.

• The query uses the primary index to search the rows and starts from the lower bound index value, set by the lower_bound parameter.

• The function will fetch a maximum of 1 rows, set by the limit parameter.

• The retrieved rows will be in ascending order, set by the reverse parameter.

The get_table_rows Result​

The JSON returned by the get_table_rows has the following structure:

{
  "rows": [
    { },
    ...
    { }
  ],
  "more": true,
  "next_key": ""
}

The "rows" field is an array of table row objects in JSON representation. The "more" field indicates that there are additional rows beyond the ones returned. The "next_key" field contains the key to be used as the lower bound in the next request to retrieve the next set of rows.

For example, the result from the previous section command contains one row, and looks similar to the one below (for privacy, the sensitive informations of the validator is replaced by "-":

{
    "rows": [
        {
            "owner": "-----.sat",
            "reward_recipient": "erc2o.xsat",
            "memo": "0x--------------------",
            "commission_rate": 1000,
            "quantity": "0.00000000 BTC",
            "qualification": "0.00000000 BTC",
            "xsat_quantity": "0.00000000 XSAT",
            "donate_rate": 0,
            "total_donated": "0.00000000 XSAT",
            "stake_acc_per_share": "0",
            "consensus_acc_per_share": "0",
            "staking_reward_unclaimed": "0.00000000 XSAT",
            "staking_reward_claimed": "0.00000000 XSAT",
            "consensus_reward_unclaimed": "0.00000000 XSAT",
            "consensus_reward_claimed": "0.00000000 XSAT",
            "total_consensus_reward": "0.00000000 XSAT",
            "consensus_reward_balance": "0.00000000 XSAT",
            "total_staking_reward": "0.00000000 XSAT",
            "staking_reward_balance": "0.00000000 XSAT",
            "latest_staking_time": "1970-01-01T00:00:00",
            "latest_reward_block": 0,
            "latest_reward_time": "1970-01-01T00:00:00",
            "disabled_staking": 0
        }
    ],
    "more": true,
    "next_key": "3815492618318908816"
}