otxn_field

Serialize and output a field from the originating transaction

Behaviour

• Find the specified sf field in the originating transaction
• Write the serialized version of the field to the output buffer

Definition

C

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

Example

C

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

Parameters

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.

Return Code

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