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Dissecting Trades in a Uniswap Transaction with the Sort API

The Uniswap contract, and mechanism behind the contract, is an interesting contract to study. We won't go through all Uniswap contracts, but just how a transaction works and visualizing the various coins that were exchanged to complete the transaction.

We'll start with the contract address we're interested in: 0x7a250d5630b4cf539739df2c5dacb4c659f2488d

Let's grab a few sample Uniswap transactions using the Sort API to see what we can learn:

POST https://api.sort.xyz/v0/transaction/
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Body:

{
  "contract_address" : "0x7a250d5630b4cf539739df2c5dacb4c659f2488d",
  "limit": 5
}
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The API call above will return the latest 5 Uniswap transactions, sorted by date descending. You may notice there are 5 primary Uniswap trading functions in the transactions:

  • swapExactTokensForTokens
  • swapExactETHForTokens
  • swapExactTokensForETH
  • swapTokensForExactTokens
  • swapETHForExactTokens

Let's focus on 'swapExactTokensForTokens' and refine our API call:

POST https://api.sort.xyz/v0/transaction/
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Body:

{
  "contract_address" : "0x7a250d5630b4cf539739df2c5dacb4c659f2488d",
  "contract_function" : "swapExactTokensForTokens",
  "limit": 10
}
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Let's look at this transaction (you can follow along in your web browser by accessing this link for the transaction hash):

0xb5f32cd7524fc4f33fd656625bb98dfed5d1396f9c6580b82a9501a89c5569f5
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View transaction information:

GET https://api.sort.xyz/v0/transaction/0xb5f32cd7524fc4f33fd656625bb98dfed5d1396f9c6580b82a9501a89c5569f5
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The first thing we'll want to look at is the function name and parameters passed into it, this is located in the top level "function" field:

"function": {
  "name": "swapExactTokensForTokens",
  "params": [
      {
          "name": "amountIn",
          "value": "100000000000000000000",
          "type": "uint256"
      },
      {
          "name": "amountOutMin",
          "value": "37541924376765909332716544",
          "type": "uint256"
      },
      {
          "name": "path",
          "value": [
              {
                  "raw": "0xb1191f691a355b43542bea9b8847bc73e7abb137",
                  "name": "Kirobo",
                  "symbol": "KIRO"
              },
              {
                  "raw": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
                  "name": "ETH",
                  "symbol": "ETH"
              },
              {
                  "raw": "0x1c7e83f8c581a967940dbfa7984744646ae46b29",
                  "name": "random",
                  "symbol": "RND"
              }
          ],
          "type": "address[]"
      },
      {
          "name": "to",
          "value": "0xeb9fbacfac3dceded5dc45daa3b319a9a1593dc7",
          "type": "address"
      },
      {
          "name": "deadline",
          "value": "1647875834",
          "type": "uint256"
      }
  ]
}
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By looking at the function call, you can get an idea of the transaction that is being requested:

  • Trade "100000000000000000000" KIRO tokens for "37541924376765909332716544" RND tokens (you'll notice the numbers seem very large, this is because they have not been shifted X decimals places based on the contract value)

Now, let's look at the logs to see what actually happened. The logs can be found in the top level "logs" field:

"logs": {
  "functions": [
      {
          "name": "Transfer",
          "type": "event",
          "params": [
              {
                  "value": "0xeb9fbacfac3dceded5dc45daa3b319a9a1593dc7",
                  "name": "from",
                  "symbol": null,
                  "type": "address"
              },
              {
                  "value": "0x5cd136e8197be513b06d39730dc674b1e0f6b7da",
                  "name": "to",
                  "symbol": "UNI-V2",
                  "type": "address"
              },
              {
                  "value": "100000000000000000000",
                  "type": "uint256",
                  "name": "value"
              }
          ],
          "function_address": {
              "value": "0xb1191f691a355b43542bea9b8847bc73e7abb137",
              "name": "Kirobo",
              "symbol": "KIRO"
          }
      },
      {
          "name": "Approval",
          "type": "event",
          "params": [
              {
                  "value": "0xeb9fbacfac3dceded5dc45daa3b319a9a1593dc7",
                  "name": "owner",
                  "symbol": null,
                  "type": "address"
              },
              {
                  "value": "0x7a250d5630b4cf539739df2c5dacb4c659f2488d",
                  "name": "spender",
                  "symbol": null,
                  "type": "address"
              },
              {
                  "value": "115792089237316195423570985008687907853269984665640564039357584007913129639935",
                  "type": "uint256",
                  "name": "value"
              }
          ],
          "function_address": {
              "value": "0xb1191f691a355b43542bea9b8847bc73e7abb137",
              "name": "Kirobo",
              "symbol": "KIRO"
          }
      },
      {
          "name": "Transfer",
          "type": "event",
          "params": [
              {
                  "value": "0x5cd136e8197be513b06d39730dc674b1e0f6b7da",
                  "name": "src",
                  "symbol": "UNI-V2",
                  "type": "address"
              },
              {
                  "value": "0x5449bd1a97296125252db2d9cf23d5d6e30ca3c1",
                  "name": "dst",
                  "symbol": "UNI-V2",
                  "type": "address"
              },
              {
                  "value": "4305548873194210",
                  "type": "uint256",
                  "name": "wad"
              }
          ],
          "function_address": {
              "value": "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2",
              "name": "ETH",
              "symbol": "ETH"
          }
      },
      {
          "name": "Sync",
          "type": "event",
          "params": [
              {
                  "value": "5340477822266522423654997",
                  "type": "uint112",
                  "name": "reserve0"
              },
              {
                  "value": "230624450502417018204",
                  "type": "uint112",
                  "name": "reserve1"
              }
          ],
          "function_address": {
              "value": "0x5cd136e8197be513b06d39730dc674b1e0f6b7da",
              "name": "Uniswap V2",
              "symbol": "UNI-V2"
          }
      },
      {
          "name": "Swap",
          "type": "event",
          "params": [
              {
                  "value": "0x7a250d5630b4cf539739df2c5dacb4c659f2488d",
                  "name": "sender",
                  "symbol": null,
                  "type": "address"
              },
              {
                  "value": "100000000000000000000",
                  "type": "uint256",
                  "name": "amount0In"
              },
              {
                  "value": "0",
                  "type": "uint256",
                  "name": "amount1In"
              },
              {
                  "value": "0",
                  "type": "uint256",
                  "name": "amount0Out"
              },
              {
                  "value": "4305548873194210",
                  "type": "uint256",
                  "name": "amount1Out"
              },
              {
                  "value": "0x5449bd1a97296125252db2d9cf23d5d6e30ca3c1",
                  "name": "to",
                  "symbol": "UNI-V2",
                  "type": "address"
              }
          ],
          "function_address": {
              "value": "0x5cd136e8197be513b06d39730dc674b1e0f6b7da",
              "name": "Uniswap V2",
              "symbol": "UNI-V2"
          }
      },
      {
          "name": "Transfer",
          "type": "event",
          "params": [
              {
                  "value": "0x5449bd1a97296125252db2d9cf23d5d6e30ca3c1",
                  "name": "from",
                  "symbol": "UNI-V2",
                  "type": "address"
              },
              {
                  "value": "0xeb9fbacfac3dceded5dc45daa3b319a9a1593dc7",
                  "name": "to",
                  "symbol": null,
                  "type": "address"
              },
              {
                  "value": "37579466301142675242049261",
                  "type": "uint256",
                  "name": "value"
              }
          ],
          "function_address": {
              "value": "0x1c7e83f8c581a967940dbfa7984744646ae46b29",
              "name": "random",
              "symbol": "RND"
          }
      },
      {
          "name": "Sync",
          "type": "event",
          "params": [
              {
                  "value": "18139246877011718508631881984",
                  "type": "uint112",
                  "name": "reserve0"
              },
              {
                  "value": "2076317830422973219",
                  "type": "uint112",
                  "name": "reserve1"
              }
          ],
          "function_address": {
              "value": "0x5449bd1a97296125252db2d9cf23d5d6e30ca3c1",
              "name": "Uniswap V2",
              "symbol": "UNI-V2"
          }
      },
      {
          "name": "Swap",
          "type": "event",
          "params": [
              {
                  "value": "0x7a250d5630b4cf539739df2c5dacb4c659f2488d",
                  "name": "sender",
                  "symbol": null,
                  "type": "address"
              },
              {
                  "value": "0",
                  "type": "uint256",
                  "name": "amount0In"
              },
              {
                  "value": "4305548873194210",
                  "type": "uint256",
                  "name": "amount1In"
              },
              {
                  "value": "37579466301142675242049261",
                  "type": "uint256",
                  "name": "amount0Out"
              },
              {
                  "value": "0",
                  "type": "uint256",
                  "name": "amount1Out"
              },
              {
                  "value": "0xeb9fbacfac3dceded5dc45daa3b319a9a1593dc7",
                  "name": "to",
                  "symbol": null,
                  "type": "address"
              }
          ],
          "function_address": {
              "value": "0x5449bd1a97296125252db2d9cf23d5d6e30ca3c1",
              "name": "Uniswap V2",
              "symbol": "UNI-V2"
          }
      }
  ],
  "num_logs": 8,
  "status": 1
}
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A few notes:

  • The "status" field is 1 or 0, and tells us whether the transaction was successful.
  • The "function_address" field tells us on which contract the function was executed.

We can see 8 function calls. There is a transfer of "KIRO" to the contract from the initiator (Transfer/Approval), then swap from "KIRO" to "ETH", then the final swap from "ETH" to "RND". The "RND" is then sent back to the initiator of the request.

We can spend a lot more time going through each function in-depth, this tutorial was meant to be a primer to get you started walking through transactions and using the Sort API.

Feel free to ask more questions on our Discord, or continue on to the Sort API documentation.

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