[GitHub] [incubator-age] afidegnum edited a comment on issue #162: ANTLR, Can you explain the parsing workflow?

[GitBox <gi...@apache.org>]

afidegnum edited a comment on issue #162:
URL: https://github.com/apache/incubator-age/issues/162#issuecomment-997583723


   This is my attempted implementation so far, which wasn't successful. I believe there is something I'm not properly addressing. 
   
   Cargo.toml
   ```
    . . . . 
   # [dependencies]
   rand = { version = "0.7.3" }
   tokio-postgres = { version = "0.5", features = ["with-chrono-0_4", "with-uuid-0_8"] }
   postgres-protocol = "*"
   postgres = "0.19.2"
   postgres-types = "*"
   
   ```
   src/main.rs
   
   ```rs
   struct AgType<'a>(&'a str);
   
   impl<'a> Display for AgType<'a>{
       
           fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
               let d: &str = self.0 ; 
               write!(f, "({})", d)
       }
   }
   
   impl<'a> FromSql<'a> for AgType<'a> {
       fn from_sql(_: &Type, raw: &'a [u8]) -> Result<AgType<'a>, Box<dyn Error + Sync + Send>> {
           let t = types::text_from_sql(raw)?;
           Ok(AgType(t))
       }
   
       fn accepts(ty: &Type) -> bool {
           ty.name() == "agtype"
       }
   }
   
   
   fn main(){
   
   pub fn graph_list() -> Result<(), Box<dyn Error>> {
       let conn_string = "host=localhost port=5432 dbname=texttest user=afidegnum password=chou1979";
       let mut client= Client::connect(conn_string, NoTls)?;
       
       &client
           .batch_execute("LOAD \'age\'")?;
   
       &client
           .batch_execute("SET search_path = ag_catalog, \"$user\", public")?;
   
        for row in &client.query("SELECT count(*) FROM ag_graph WHERE name= 'text_test'", &[])?{
            println!("{}", row.get::<_, i64>(0));
            let  count: i64 = row.get(0); println!("{}", count);
            println!("{}", count);
            dbg!(count);
        }
   
       
   
       for row in client.query("SELECT * from cypher('text_test', $$ MATCH (V:node) RETURN id(V) as vid $$) as (vid agtype)", &[])? {
           let path: AgType = row.get(0);
           println!("{}", path)
        }
       Ok(())
   }
   
   
   let res = graph_list();
   match res {
           Ok(r) => {println!("Succeeded! {:?} ", r);},
           Err(e) => {println!("Error: {}!", e);}
       }
   
   
   
   }
   ```
   ```
   1
   [src/lib.rs:20] count = 1
   1
   1
   Error: db error: ERROR: no binary output function available for type agtype!
   ```
   
   


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