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Core Adapters [v1]

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Adapters

Core adapters are the built-in functionality that every Chainlink node supports. Strung together, they act as tasks that need to be performed to complete a Job.

Adapters that are prefixed with “Eth” refer to tasks that post data onto the chain. Here are some examples of the data types that adapters convert data to.

Name Core Adapter Ethereum Data Type
Signed Integers EthInt256 int256
Unsigned Integers EthUint256 uint256
Bytes EthBytes32 bytes32
Boolean EthBool bool

You can learn more about Solidity data types here.

Compare

This core adapter compares a user-specified value with the value from the previous adapter’s result.

Parameters

  • operator: the operator used to compare values. You may use one of the following:
    • eq: Equals
    • neq: Not equals
    • gt: Greater than
    • gte: Greater than or equals to
    • lt: Less than
    • lte: Less than or equals to
  • value: the value to check against the previous adapter’s result. May be a string or a number, but if the value is a string, only eq and neq may be used.

Solidity Example

req.addInt("value", 10000);
req.add("operator", "gte");

Copy

The core adapter walks the copyPath specified and returns the value found at that result. If returning JSON data from an external adapter, you will need to use this adapter to parse the response.

Parameters

  • copyPath: takes an array of strings, each string being the next key to parse out in the JSON object or a single dot-delimited string.

Solidity Example

For the JSON object:

{ "RAW": { "ETH": { "USD": { "LASTMARKET": "_someValue" } } } }

You would use the following for an array of strings:

string[] memory path = new string(4);
path[0] = "RAW";
path[1] = "ETH";
path[2] = "USD";
path[3] = "LASTMARKET";
req.addStringArray("copyPath", path);

Or the following for a single comma-delimited string:

req.add("copyPath", "RAW,ETH,USD,LASTMARKET");

Job Specification Example

{
  "type": "Copy",
  "params": {
    "copyPath": ["RAW", "ETH", "USD", "LASTMARKET"]
  }
}

For arrays, you can access the path of an array by using the index. If this is your JSON:

{ "endpoint": [{ "path": "value" }] }

You could get the "value" by:

req.add("copyPath", "endpoint.0.path");

EthBool

The core adapter reads the given Boolean value and then converts it into Solidity’s bool format.

Parameters

None taken.

EthBytes32

The core adapter formats its input into a string and then converts it into Solidity’s bytes32 format.

Parameters

None taken.

EthInt256

The core adapter formats its input into an integer and then converts it into Solidity’s int256 format.

Parameters

None taken.

EthTx

The core adapter takes the input given and places it into the data field of the transaction. It then signs an Ethereum transaction and broadcasts it to the network. The task is only completed once the transaction’s confirmations equal the MIN_OUTGOING_CONFIRMATIONS amount.

If the transaction does not confirm by the time ETH_GAS_BUMP_THRESHOLD number of blocks have passed since initially broadcasting, then it bumps the gas price of the transaction by ETH_GAS_BUMP_WEI.

Parameters

  • address: the address of the Ethereum account which the transaction will be sent to.
  • functionSelector: (optional) the function selector of the contract which the transaction will invoke. functionSelector is placed before dataPrefix and the adapter’s input in the data field of the transaction.
  • dataPrefix: (optional) data which will be prepended before the adapter’s input, but after the functionSelector in the transaction’s data field.
  • value: (optional) data to send to the function, will append after the dataPrefix payload if it’s included. Will automatically come from the previous task.

EthUint256

The core adapter formats its input into an integer and then converts it into Solidity’s uint256 format.

Parameters

None taken.

HttpGet

The core adapter will report the body of a successful GET request to the specified get, or return an error if the response status code is greater than or equal to 400.

Parameters

  • get: takes a string containing the URL to make a GET request to.
  • queryParams: takes a string or array of strings for the URL’s query parameters.
  • extPath: takes a slash-delimited string or array of strings to be appended to the job’s URL.
  • headers: takes a object containing keys as strings and values as arrays of strings.

Solidity Example

req.add("get", "http://example.com");
req.add("queryParams", "firstKey=firstVal&secondKey=secondVal");
req.add("extPath", "price/BTC/USD");

Job Specification Example

{
  "type": "HttpGet",
  "params": {
    "get": "https://example.com/some-endpoint",
    "headers": {
      "X-API-Key": ["abc123abc123abc123abc123"]
    }
  }
}

If you really must access one of these IPs, you can use the HTTPGetWithUnrestrictedNetworkAccess adapter instead.

HttpPost

The core adapter will report the body of a successful POST request to the specified post, or return an error if the response status code is greater than or equal to 400.

Parameters

  • post: takes a string containing the URL to make a POST request to.
  • headers: takes a object containing keys as strings and values as arrays of strings.
  • queryParams: takes a string or array of strings for the URL’s query parameters.
  • extPath: takes a slash-delimited string or array of strings to be appended to the job’s URL.
  • body: the JSON body (as a string) that will be used as the data in the request.

Solidity Example

req.add("post", "http://post.example.com");
req.add("queryParams", "firstKey=firstVal&secondKey=secondVal");
req.add("extPath", "price/BTC/USD");

Job Specification Example

{
    "type": "HttpPost",
    "params": {
        "post": "https://example.com/some-endpoint",
        "headers": {
            "X-API-Key": [
                "abc123abc123abc123abc123"
            ]
        }
    }
}

If you really must access one of these IPs, you can use the HTTPPostWithUnrestrictedNetworkAccess adapter instead.

JsonParse

The core adapter walks the path specified and returns the value found at that result. If returning JSON data from the HttpGet or HttpPost adapters, you must use this adapter to parse the response.

Parameters

  • path: takes an array of strings, each string being the next key to parse out in the stringified JSON result or a single dot-delimited string.

Solidity Example

For the stringified JSON:

{ "RAW": { "ETH": { "USD": { "LASTMARKET": "_someValue" } } } }

You would use the following for an array of strings:

string[] memory path = new string[](4);
path[0] = "RAW";
path[1] = "ETH";
path[2] = "USD";
path[3] = "LASTMARKET";
req.addStringArray("path", path);

Or the following for a single comma-delimited string:

req.add("path", "RAW,ETH,USD,LASTMARKET");

Job Specification Example

{
  "type": "JsonParse",
  "params": {
    "path": ["RAW", "ETH", "USD", "LASTMARKET"]
  }
}

Parsing Arrays

req.add("path", "3,standardId");

The above example parses the 4th object of the following JSON response and returns 677 as a result:

;[
  {
    standardId: 20,
    name: "ERC-20",
  },
  {
    standardId: 721,
    name: "ERC-721",
  },
  {
    standardId: 1155,
    name: "ERC-1155",
  },
  {
    standardId: 677,
    name: "ERC-677",
  },
]

Multiply

The core adapter parses the input into a float and then multiplies it by the times field.

Parameters

  • times: the number to multiply the input by.

Solidity Example

run.addInt("times", 100);

NoOp

The core adapter performs no operations, simply passing the input on as output. Commonly used for testing.

Parameters

None taken.

NoOpPend

The core adapter performs no operations, and marks its task run pending. Commonly used for testing.

Parameters

None taken.

Quotient

Quotient

The core adapter gives the result of x / y where x is a specified value (dividend) and y is the input value (result).

This can be useful for inverting outputs, e.g. if your API only offers a USD/ETH conversion rate and you want ETH/USD instead you can use this adapter with a dividend of 1 to get the inverse (i.e. 1 / result).

Parameters

  • dividend: the number which is divided by the result

Sleep

The core adapter will pause the current task pipeline for the given duration.

Parameters

  • until: the UNIX timestamp of when the job should stop sleeping and resume at the next task in the pipeline.

Solidity Example

req.addUint("until", now + 1 hours);

Job Specification example

{
  "initiators": [
    {
      "type": "web",
      "params": {
      }
    }
  ],
  "tasks": [
    {
      "type": "sleep",
      "params": {
        "until": "1605651000"
      }
    }
  ]
}

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