elefant-tools 0.0.2

A library for doing things like pg_dump and pg_restore, with extra features, and probably more bugs.
Documentation 
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use crate::postgres_client_wrapper::FromRow;
use crate::schema_reader::define_working_query;
use crate::PostgresColumn;
use tokio_postgres::Row;

#[derive(Debug, Eq, PartialEq)]
pub struct TableColumnsResult {
    pub schema_name: String,
    pub table_name: String,
    pub column_name: String,
    pub ordinal_position: i16,
    pub is_nullable: bool,
    pub data_type: String,
    pub column_default: Option<String>,
    pub generated: Option<String>,
    pub comment: Option<String>,
    pub array_dimensions: i32,
    pub data_type_length: Option<i32>,
}

impl FromRow for TableColumnsResult {
    fn from_row(row: Row) -> crate::Result<Self> {
        Ok(TableColumnsResult {
            schema_name: row.try_get(0)?,
            table_name: row.try_get(1)?,
            column_name: row.try_get(2)?,
            ordinal_position: row.try_get(3)?,
            is_nullable: row.try_get(4)?,
            data_type: row.try_get(5)?,
            column_default: row.try_get(6)?,
            generated: row.try_get(7)?,
            comment: row.try_get(8)?,
            array_dimensions: match row.try_get(9) {
                Ok(d) => d,
                Err(_) => row.try_get::<_, i16>(9)? as i32,
            },
            data_type_length: row.try_get(10)?,
        })
    }
}

impl TableColumnsResult {
    pub fn to_postgres_column(&self) -> PostgresColumn {
        PostgresColumn {
            name: self.column_name.clone(),
            is_nullable: self.is_nullable,
            ordinal_position: self.ordinal_position as i32,
            data_type: self.data_type.clone(),
            default_value: self.column_default.clone(),
            generated: self.generated.clone(),
            comment: self.comment.clone(),
            array_dimensions: self.array_dimensions,
            data_type_length: self.data_type_length,
        }
    }
}

//language=postgresql
define_working_query!(
    get_columns,
    TableColumnsResult,
    r#"
select ns.nspname,
       cl.relname,
       attr.attname,
       attr.attnum,
       (attr.attnotnull OR t.typtype = 'd'::"char" AND t.typnotnull) = false as is_nullable,
       coalesce(non_array_type.typname, t.typname),
       CASE
           WHEN attr.attgenerated = ''::"char" THEN pg_get_expr(ad.adbin, ad.adrelid)
           ELSE NULL::text
           END::text                           AS column_default,
       CASE
           WHEN attr.attgenerated <> ''::"char" THEN pg_get_expr(ad.adbin, ad.adrelid)
           ELSE NULL::text
           END::text                           AS generation_expression,
         des.description,
         attr.attndims as array_dimensions,
       information_schema._pg_char_max_length(coalesce(non_array_type.oid, t.oid), attr.atttypmod) as data_type_length
from pg_attribute attr
         join pg_class cl on attr.attrelid = cl.oid
         join pg_type t on attr.atttypid = t.oid
         join pg_namespace ns on ns.oid = cl.relnamespace
         left join pg_attrdef ad on attr.attrelid = ad.adrelid and attr.attnum = ad.adnum
         left join pg_description des on des.objoid = cl.oid and des.objsubid = attr.attnum
         left join pg_type non_array_type on non_array_type.oid = t.typelem and non_array_type.typarray = t.oid
         left join pg_depend dep on dep.objid = ns.oid
where cl.relkind in ('r', 'p')
  and cl.oid > 16384
  and attr.attnum > 0
  and (dep.objid is null or dep.deptype <> 'e' )
order by ns.nspname, cl.relname, attr.attnum;
"#
);