derive_redis_json/
lib.rs

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#![recursion_limit = "128"]

#[macro_use]
extern crate quote;

#[macro_use]
extern crate syn;

extern crate proc_macro;

use proc_macro::TokenStream;
use syn::DeriveInput;

#[proc_macro_derive(RedisJsonValue)]
pub fn redis_json_value(input: TokenStream) -> TokenStream {
  let input = parse_macro_input!(input as DeriveInput);
  let struct_type = input.ident;

  let expanded = quote! {
    impl redis::ToRedisArgs for #struct_type {
        fn write_redis_args<W>(&self, out: &mut W)
        where
          W: ?Sized + redis::RedisWrite,
        {
          out.write_arg(&serde_json::to_vec(self).expect("JSON encoding failed"));
        }
      }
      
      impl redis::FromRedisValue for #struct_type {
        fn from_redis_value(v: &redis::Value) -> redis::RedisResult<Self> {
          match *v {
            redis::Value::Data(ref bytes) => Ok(serde_json::from_slice(bytes).map_err(|err| {
              (
                redis::ErrorKind::TypeError,
                "JSON deserialize failed",
                err.to_string(),
              )
            })?),
            _ => Err(
              (
                redis::ErrorKind::TypeError,
                "invalid response type for JSON",
              )
                .into(),
            ),
          }
        }
      }
  };

  TokenStream::from(expanded)
}