count with has_many in rails

Question

I've got an `Order` and `Orderdetails` ``` Orderdetails belongs_to Order Order has_many Orderdetails ``` I am trying to convert the following query to ActiveRecord `count` function ``` select Count(*) from orderdetails A, orders B where A.prodid='6' and A.orderid= B.id and B.custid='11' ``` I tried: ``` @count = Orderdetail.count(:conditions => "prodid = 6 and order.custid = 11") ``` However, this gives error: ``` PGError: ERROR: syntax error at or near "order" LINE 1: ...unt_all FROM "orderdetails" WHERE (prodid = 6 and order.cust... ``` Edit I changed to orders but now i get this error: ActiveRecord::StatementInvalid: PGError: ERROR: missing FROM-clause entry for table "orders" LINE 1: ...unt_all FROM "orderdetails" WHERE (prodid = 6 and orders.cus...

Accepted Answer

You need to add `:joins => :order'`, because your condition contains element from orders table (that's why you get error `missing FROM-clause`), try:

```
@count = Orderdetail.count(:joins => :order, :conditions => "prodid = 6 and orders.custid = 11")
```

Also it better (safer) to use array in conditions:

```
@count = Orderdetail.count(:joins => :order, :conditions => ["prodid = ? and orders.custid = ?", 6, 11])
```

count with has_many in rails

Solution

Problem