otxn_field

Serialize and output a field from the originating transaction

Behaviour

C

• Find the specified sf field in the originating transaction

• Write the serialized version of the field to the output buffer

Javascript

• Retrieve the value of a specific field in the originating transaction.

• Returns the value of the specified field as an array of numbers, or an ErrorCode if the lookup fails.

Definition

C

int64_t otxn_field (
    uint32_t write_ptr,
    uint32_t write_len,
    uint32_t field_id
);

Javascript

function otxn_field(field_id: number): ErrorCode | ByteArray

Example

C

int64_t account_field_len = 
    otxn_field(account_field, 20, sfAccount);

Javascript

const account_field = otxn_field(sfAccount)

Parameters

C

Name	Type	Description
write_ptr	uint32_t	Pointer to a buffer of a suitable size to store the output.
write_len	uint32_t	Length of the output buffer.
field_id	uint32_t	The sf code of the field you are searching for. To compute this manually take the serialized type and shift it into the 16 highest bits of uint32_t, then take the field and place it in the 16 lowest bits. For example: sfEmitNonce has type 5 and field 11 thus its value is 0x050BU

❗️Important

The field code is not written to the output buffer, only the payload of the field is.

At time of writing for Hooks Public Testnet, STI_ACCOUNT fields like sfAccount are returned without the leading variable length byte.

Javascript

Name	Type	Description
field_id	number	Returns the value of the specified field as an array of numbers, if the lookup fails.

Return Code

C

Type	Description
int64_t	The number of bytes written If negative, an error: OUT_OF_BOUNDS - pointers/lengths specified outside of hook memory. TOO_SMALL - output buffer was not large enough to hold the serialized field INVALID_FIELD - the sf field_id was invalid DOESNT_EXIST - the field was not found in the originating transaction

Javascript

Type	Description
ByteArray or ErrorCode	Returns the value of the specified field as an array of numbers, or an ErrorCode if the lookup fails.