json - Return flat object from sequelize with association

Question

I am working on converting all my queries in sequelize. The problem I have come across is that when select queries include associations (ex. one to many), the object I get is an array of nested objects.

It looks something like:

[   
  {
    "field1": "someval",
    "field2": "someval1",
    "assoc_table": {
      "field_a": 1,
      "field_b": "someval"
    }   
  },   
  {
    "field1": "someval",
    "field2": "someval3",
    "assoc_table": {
      "field_a": 5,
      "field_b": "someval"
    }   
  },   
  {
    "field1": "someval",
    "field2": "someval3",
    "assoc_table": {
      "field_a": 12,
      "field_b": "someval"
    }   
   } 
]

I tried to use different modules to flatten the objects (inside a loop, each object individually), but I always got an error telling that what I was trying to flatten were not just objects.

Moreover, I would prefer avoiding the part where objects are flattened, and simply get a flat result with sequelize.

The sequelize code looks something like this:

models.table1.findAll({
    attributes: ['field1', 'field2'],
    where: {field1: someval},
    include: [{model: models.assoc_table, required: true, attributes:['field_a', 'field_b']}]
}).then(function (result) {
    res.send(result);
}).catch(function(error) {
    console.log(error);
});

Answer 1

Part of your issue is probably that your result is an array of model instances, so you might be having issues flattening it if you didn't call toJSON on the elements in the array. I provided code that would flatten your example:

result.forEach(obj => { 
    Object.keys(obj.toJSON()).forEach(k => {
        if (typeof obj[k] === 'object') {       
            Object.keys(obj[k]).forEach(j => obj[j] = obj[k][j]);
        }
    });
});

You can also add raw: true as an option to findAll, which will flatten your object, but it will look like this:

[   
  {
    "field1": "someval",
    "field2": "someval1",
    "assoc_table.field_a": 1,
    "assoc_table.field_b": "someval"
  },
  ...
]