Named Credential Formula Functions

Formula functions can be used in the value field of a custom header of a named credential or external credential.

A Binary Large OBject (BLOB) is a collection of binary data stored as a single entity. For named credentials, BLOBs can store binary executable code used in custom header formulas.

Formula Functions

Function	Description
BASE64DECODE(expr)	Input: String Output: BlobValue Description: Decode the Base64-encoded String expression to binary.
BASE64ENCODE(expr)	Input: BlobValue Output: String Description: Encode the binary BLOB expression as a Base64-encoded String.
BLOB(expr)	Input: String Output: BlobValue Description: Convert the value to a UTF-8 binary BLOB.
HASH(algorithm, expr)	Input: String, BlobValue Output: BlobValue Description: Given a binary value to hash, use algorithm to get the binary hash. The only supported hashing algorithm is SHA-256.
HEX(expr)	Input: BlobValue Output: String Description: Represents the given BLOB expression as a base-16 lower-case encoded String. This hex encoding contains the binary data expected by encryption functions.
HMAC(algorithm, valueToSign, secretSigningKey)	Input: String, BlobValue, BlobValue Output: BlobValue< li>Description: Use algorithm to sign the given binary valueToSign with a binary secret signing key. The resulting message authentication code is a binary value. The only supported algorithm is SHA-256.

Examples

This example shows encoding a username and password stored in an external credential. The BLOB function first converts a string of form username:password into a binary. BASE64ENCODE then converts the binary into an encoded string. myExternalCredential is the name of an external credential.

1BASE64ENCODE(BLOB($Credential.myExternalCredential.Username &amp; ':' &amp; $Credential.myExternalCredential.Password))

This example sets a header named X-Username with a base-16, SHA-256-hashed username as the value. req is an HTTPRequest. Username is an authentication parameter attached to a permission set mapping.

1req.setHeader('X-Username', '{!HEX(HASH(\'SHA-256\', BLOB($Credential.myExternalCredential.Username)))}');

This example sets the X-Body header as the base-16, hashed evaluated body, meaning that all formulas within the request body are evaluated. BLOB isn’t required here because $Credential.myExternalCredential.Body is returned as a BLOB type, rather than as a String.

1req.setHeader('X-Body', '{!HEX(HASH(\'SHA-256\', $Credential.myExternalCredential.Body))}');

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