Embedded Objects

[RealmBot]

See RPM-72 for details.

• Expand embedded object schema
• Accessor (node.js)
• Accessor (RN)
• Tests

PR: #2724

[kneth]

The schema can be extended to look like:

const Person = {
  name: 'Person',
  primaryKey: 'id',
  embeddedObject: false,   // this is the default value
  properties: {
    id: 'int',
    firstName: 'string',
    lastName: 'string',
    robots: 'Robot[]'
  }
};

const Robot = {
  name: 'Robot',
  embeddedObject: true,
  properties: {
    name: 'string',
    builder: 'string'
  }
};

The new schema attribute embeddedObject is true if a table/class can only be used as an embedded object.

Creating a nested object:

realm.create('Person', {
  id: 42,
  firstName: 'Arthur',
  lastName: 'Dent',
  robots: [{
    name: 'Marvin',
    builder: 'Sirius Cybernetics Corporation'
  }]
});

Alternatively, the object can be created in two steps:

let marvin = realm.create('Robot', {
  name: 'Marvin',
  builder: 'Sirius Cybernetics Corporation'
  }
);
realm.create('Person', {
  id: 42,
  firstName: 'Arthur',
  lastName: 'Dent',
  robots: [marvin]
});

[kraenhansen]

I would suggest the shorter embedded over embeddedObject.

[kraenhansen]

Also - I think the two step approach of first creating an embedded object and then embedding it should not be supported, as the scope reads:

An embedded object can only be created along with a link to it.

If it was not the case, what would happen to the embedded object if it never gets embedded?

[kraenhansen]

Another suggestion could be to allow defining the schema of an embedded object, in the definition of the parent object:

const Person = {
  name: 'Person',
  primaryKey: 'id',
  properties: {
    id: 'int',
    firstName: 'string',
    lastName: 'string',
    robots: {
      type: 'list',
      objectType: {
        name: 'Robot',
        properties: {
          name: 'string',
          builder: 'string'
        }
      }
    }
  }
};

The user don't need to specify that the "Robot" is embedded as this is the only case where "objectType" is an object instead of a string.

A simple (not a list) link to an embedded object could be represented as:

const Person = {
  name: 'Person',
  primaryKey: 'id',
  properties: {
    id: 'int',
    firstName: 'string',
    lastName: 'string',
    robot: {
      name: 'Robot',
      properties: {
        name: 'string',
        builder: 'string'
      }
    }
  }
};

We can identify the embedded object definition as its now missing a type field and defines a properties object.

[cmelchior]

Keep in mind that embedded Object is allowed to be embedded in multiple places (e.g the type of the parent might not be fixed)

[kneth]

Keep in mind that embedded Object is allowed to be embedded in multiple places (e.g the type of the parent might not be fixed)

The suggestion by @kraenhansen above is very natural for a JS developer - but is a restriction compared to my initial suggestion. Therefore I believe we should support both.

[kraenhansen]

As @kneth's suggestion is the only one that supports the full scope of the feature, I think we should start with that and keep my suggestion as an idea for future improvements.

[blagoev]

Can we move the discussion on the design doc. Thus having the final decision there and iterating over it at once

[blagoev]

I think this should/will not be allowed in the other SDKs

let marvin = realm.create('Robot', {
  name: 'Marvin',
  builder: 'Sirius Cybernetics Corporation'
  }
);

[blagoev]

UPDATE on the above: there is no consensus on that

[kraenhansen]

Can we move the discussion on the design doc. Thus having the final decision there and iterating over it at once

Sure thing - I think @kneth's intention on his initial comment was just to kick off a discussion before we started adding stuff to the doc. I see no reason that we cannot more this into the doc.

I think this should/will not be allowed in the other SDKs

let marvin = realm.create('Robot', {
  name: 'Marvin',
  builder: 'Sirius Cybernetics Corporation'
  }
);

I agree, thats what I ment by #2676 (comment).

[reanzi]

const Person = {
  name: 'Person',
  primaryKey: 'id',
  properties: {
    id: 'int',
    firstName: 'string',
    lastName: 'string',
    robots: {
      type: 'list',
      objectType: {
        name: 'Robot',
        properties: {
          name: 'string',
          builder: 'string'
        }
      }
    }
  }
};

I having to trouble to embed data , tried above @kraenhansen approach but didn't work,
I get this error:

Error: Exception in HostFunction: Error while parsing property 'passangers' of object with name 'Permits'. Error: objectType must be of type 'string', got ([object Object])

This is My Schema :
I have used both approacht (commented out the one from the docs for now)

const PermitSchema = {
  name: 'Permits',
  properties: {
    _id: 'objectId?',
    __v: 'int?',
    _partition: 'string',
    cargo_type: 'string?',
    location: 'string?',
    passangers: {
      type: 'list',
      objectType: {
        name: 'Passanger',
        properties: {
          name: 'string?',
          phone: 'string?',
        },
      },
    },
    // quantity: {type: 'list', objectType: 'Quantity'},
    where_to: 'string?',
    updatedAt: 'date?',
  },
  primaryKey: '_id',
};

const permit_quantitySchema = {
  name: 'Quantity',
  embedded: true,
  properties: {
    amount: 'int?',
    unit: {type: 'string?', enum: ['ndoo', 'djaba', 'pieces', 'gunia']},
  },
};

export default PermitSchema;