Function set_field 

pub unsafe fn set_field<T: EndianScalar>(
    buf: &mut [u8],
    table_loc: usize,
    field: &Field<'_>,
    v: T,
) -> FlatbufferResult<()>

Sets any scalar field given its exact type. Returns error if the field is not originally set or is with non-scalar value.

Safety

[buf] must contain a valid root table and valid offset to it.