exchange.IO("decode", ...)

Decodes data.

    
    
    
exchange.IO(k, dataFormat, data)

Examples

• The inverse operation of the exchange.IO("encode", ...) function.

  
      javascript
      
      
  function main() {
      // A tuple is written in parentheses, with fields arranged by position; here is a three-field
      // tuple plus a bytes parameter
      var types = "(uint256,uint8,address),bytes"
  
      // Tuple values are passed as an array by position
      var ret = exchange.IO("encode", types, [30, 20, "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"],
          "0011")
      Log("encode: ", ret)
      // A literal tuple has no field names, so fields are numbered by position as Field1, Field2...
      // To use meaningful field names,
      // you need to register the contract ABI first with exchange.IO("abi", ...), refer to the next
      // example
      var rawData = exchange.IO("decode", types, ret)
      Log("decode:", rawData)
  
      // Output: decode: [{"Field1":"30","Field2":20,"Field3":"0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"}, "0011"]
  }
  

• The following example first performs encodePacked encoding on the path parameter, because the exactOutput method call to be encoded later requires path as a parameter. Then it performs encode encoding on the exactOutput method of the router contract, which has only one parameter of type tuple. The method name exactOutput is encoded as: 0x09b81346. Finally, the exchange.IO("decode", ...) method is used to decode according to (bytes,address,uint256,uint256) to obtain decodeRaw, whose fields are numbered by position as Field1 to Field4, and the value of each field corresponds in order to the contents of the variable dataTuple.

  
      javascript
      
      
  function main() {
      // register SwapRouter02 abi
      var walletAddress = "0x398a93ca23CBdd2642a07445bCD2b8435e0a373f"
      var routerAddress = "0x68b3465833fb72A70ecDF485E0e4C7bD8665Fc45"
      var abi = `[{"inputs":[{"components":[{"internalType":"bytes","name":"path","type":"bytes"},{"internalType":"address","name":"recipient","type":"address"},{"internalType":"uint256","name":"amountOut","type":"uint256"},{"internalType":"uint256","name":"amountInMaximum","type":"uint256"}],"internalType":"struct IV3SwapRouter.ExactOutputParams","name":"params","type":"tuple"}],"name":"exactOutput","outputs":[{"internalType":"uint256","name":"amountIn","type":"uint256"}],"stateMutability":"payable","type":"function"}]`
      // The abi only contains the partial content of the exactOutput method; the complete abi can be
      // found by searching online
      exchange.IO("abi", routerAddress, abi)
  
      // encode path
      var fee = exchange.IO("encodePacked", "uint24", 3000)
      var tokenInAddress = "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"
      var tokenOutAddress = "0xdac17f958d2ee523a2206206994597c13d831ec7"
      var path = tokenInAddress.slice(2).toLowerCase()
      path += fee + tokenOutAddress.slice(2).toLowerCase()
      Log("path:", path)
  
      var dataTuple = {
          "path" : path,
          "recipient" : walletAddress,
          "amountOut" : 1000,
          "amountInMaximum" : 1,
      }
      // encode SwapRouter02 exactOutput
      var rawData = exchange.IO("encode", routerAddress, "exactOutput", dataTuple)
      Log("method hash:", rawData.slice(0, 8))
      // Output: 09b81346
      Log("params hash:", rawData.slice(8))
  
      // decode exactOutput params
      var decodeRaw = exchange.IO("decode", "(bytes,address,uint256,uint256)", rawData.slice(8))
      Log("decodeRaw:", decodeRaw)
  }
  

Returns

Arguments

See Also

Remarks

In terms of data processing, the exchange.IO() function supports not only encoding (encode) but also decoding (decode).

exchange.IO("unpack", ...) is an alias of exchange.IO("decode", ...).