how to stop rethinkdb converting object to array?

Question

I'm very confused here. I'm passing an object called ScheduleAdd, and using insertAt to enter that object into an array called 'schedules' that exists in each document in the table 'teachers'. Rethink is throwing the error "Inserted value must be an OBJECT (got ARRAY)". It shows me an array that consists of my passed object with square brackets around it.

Code:

var scheduleAdd = {};
    scheduleAdd.schedule = name;
    scheduleAdd.visible = 'yes';
    console.log(scheduleAdd);  
r.db('test').table('teachers').update(function(teacher) {return teacher('schedules').insertAt(0,scheduleAdd)}).run(connection, function(err, result) {
    if (err) throw err;
    ;
    console.log('updated teacher schedules');
    console.log(result);
        });
     });

As an example, I might pass the object:

{ schedule: 'weekend', visible: 'yes' }

The console.log confirms that the object is well formed. However Rethink will then throw the error:

'Inserted value must be an OBJECT (got ARRAY):\n["{\\n  \\"schedule\\": \\"weekend\\",\\n      \\"visible\\": \\"yes\\"\\n}"]',

Any idea why my object is being converted into an array, and how I can stop it from happening? Thanks!

jek · Accepted Answer · 2014-08-30 03:04:22Z

4

From the documentation, update 1 expects either an object or an expression returning an object, in your case you are passing in the expression:

function(teacher) {return teacher('schedules').insertAt(0,scheduleAdd)}

From the documentation as well, insertAt "returns the modified array" 2. This means that your expression is returning the new array of schedules rather than a object for the update. As a result, update ends up trying to insert an Array when it expects an Object. To demonstrate this, try running:

r.db('test').table('teachers').insert({schedules:[{name:"first"}]});
r.db('test').table('teachers').update(function(teacher) {return teacher('schedules').insertAt(0,{name:"second"})})

You will get the error:

Inserted value must be an OBJECT (got ARRAY):
[{
        "name": "second"
    }, {
        "name": "first"
    }]

The modified array with {"name":"second"} is correctly prepended to the existing schedules array from the row, and the new array is returned by insertAt. However, update cannot insert an array so the error is thrown.

To fix this, you could use:

r.db('test').table('teachers').update({schedules : r.row('schedules').insertAt(0,scheduleAdd)})

or

r.db('test').table('teachers').update(function(teacher) {return {schedules : teacher('schedules').insertAt(0,scheduleAdd)}})

answered Aug 30, 2014 at 3:04

jek

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3 Comments

BarthesSimpson Over a year ago

Thanks - that's perfect. How about when I want to delete the entry (after having entered in several other objects)? I know I can use deleteAt, but I'm having a hard time figuring out the index number of the element I want to delete within the schedules array (which will be different for each teacher).

jek Over a year ago

@user3220303 You could use deleteAt or difference, or any number of other functions, it really depends on what information you have about the schedule you want to remove from the array. If you are still having trouble, I would recommend opening up a new question with some more details.

BarthesSimpson Over a year ago

difference made all the difference. Thanks again.

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