Chai testing - create object to test? - figured this out

UPDATE: I finally figured this out. I removed the .query() and added the param to the .get()

.get('/api/books/'+idToQuery)
      test('Test GET /api/books/[id] with valid id in db',  function(done){
        chai.request(server)
        // create test entry in database
        .post('/api/books')
        .send({
          title: 'Test Book - valid id'
        })
        .end(function(err,res){          
          let idToQuery = res.body._id; // this successfully sends back the '_id' of the new data created in the .post()
          chai.request(server)        
          .get('/api/books')
          .query({_id: idToQuery }) // query with new '_id' 
          .end(function(err, res){
            console.log(res.body) // this prints out entire database NOT just the one I am querying for
            assert.equal(res.status, 200);
            assert.isObject(res.body, 'response should be an object');
            assert.property(res.body, 'title', 'Test Book - valid id');         
            done();
          });
        });
      });

The line: .query({_id: idToQuery }) does not seem to be working as the console.log(res.body) prints out all the database entries. So obviously the asserts fail as it doesn’t know which one to test.

Am I doing this correctly? or is there some other way to create a test entry to use for the asserts()?