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

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

Example

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