Dynamoose List of Maps in schema

Question

I have in my DynamoDB database a table containing an element as a List of Maps. Each Map item does not have any specific structure.

I've tried to describe it like this:

const schema = new dynamoose.Schema({
  Id: {
    type: String,
    hashKey: true,
    required: true
  },
  Name: {
    type: String,
    required: true
  },
  Content: {
    type: 'list',
    list: [Map]
  }
},
{
  useNativeBooleans: true,
  useDocumentTypes: true,
  saveUnknown: true
})

However, every item in Content equals to {}. I am able to retrieve the data when changing list: [Map] to list: [String], but I would like to have it in Json not in a string containing DynamoDB Json format.

How can I do that?

Answer 1

Ok so I was faced with a similar problem I finally managed to solve it only for maps that were of a specific structure, that is all of the entries are of the same type by looking in the tests for dynamoose and working out the syntax. The following code will save addressHeld as a list of maps in dynamodb.

You can see from the scan that you get back an array of objects on query.

var Address = dynamoose.model('Address', {
    HouseNumber: {
        type: Number,
        hashKey: true
    },
    Postcode: {
        type: String,
        rangeKey: true
    }
}, { useDocumentTypes: true });

var dogSchema = new dynamoose.Schema({
    ownerId: {
        type: Number,
        hashKey: true
    },
    address: {
        type: 'list',
        list: [
            {
                HouseNumber: { type: Number, require: true },
                Postcode: { type: String, require: true },
            }
        ],
        require: true
    },
}, { useDocumentTypes: true });

var Dog = dynamoose.model('Dog', dogSchema, options);

var Address1 = new Address(
    {
        HouseNumber: 1,
        Postcode: "LS114RF"
    });
var Address2 = new Address(
    {
        HouseNumber: 2, Postcode: "NN22NX"
    });

var odie = new Dog({
    ownerId: 1,
    address: [Address1, Address2]
});

odie.save(function (err) {
    if (err) { return console.log(err) }
    console.log('Ta-da!');
});


Dog.scan().exec((err, dog) => {
    console.log(dog);
});

You can save a list of Maps, but dynamoose doesn't know what to do with them so it stores them as strings, this is acheived by setting the list type to 'Object'

You could take a look at attributeToDynamo in the api, but if the objects are utterly random I am not sure your are going to be able to do what you want in dynamoose.

You could always fall back to the raw aws-sdk if all else failed. Hope this helps.