Postgres synchronisation unnecessarily drops column with data type "float"

Issue type:

[ ] question [x] bug report [ ] feature request [ ] documentation issue

Database system/driver:

[ ] cordova [ ] mongodb [ ] mssql [ ] mysql / mariadb [ ] oracle [x] postgres [ ] sqlite [ ] sqljs [ ] react-native

TypeORM version:

[ ] latest [ ] @next [x] 0.2.5 Postgres v10

Steps to reproduce or a small repository showing the problem:

Create an Entity with a column of data type float:

@Entity()
export class FloatTest{

  @PrimaryColumn()
  id: number

  @Column('float')
  some_num: number
}

Add some data to the table:

const con = await createConnection({
    ...,
    synchronize: true,
    logging: true
  })
await con.manager.save(FloatTest, { id: 0, sum_num: 10.51 })

On the initial run this all works fine – run it again however and you’ll get an error like the following: column "some_num" contains null values. With logging enabled the “sum_num” column is clearly being dropped and rebuilt.

I think this error is due to Postgres using double precision as float internally(see https://www.postgresql.org/docs/10/static/datatype-numeric.html section 8.1.3). This seems to be the case when the column check SQL is run: SELECT *, "udt_name"::"regtype" AS "regtype" FROM "information_schema"."columns".... The “regtype” for the float data type returns double precision.

The solution, I think is to add an additional check in the normalizeType function in PostgresDriver.ts like so:

else if (column.type === "float") {
   return "double precision";
}

Thanks for the great ORM!

[Alex0007]

Confirming this bug on typeorm@next version

[mattb-prg]

@serranoarevalo Yep, just use the double precision type instead of float when defining your column. Or modify the source to add the extra conditional statement(see the very end of my original post)