[help] how to save model with given id

Requirement

We need to save a model with given id.

Question

What schema should I defined? And when save a mode, should I add id property.

Currently my code is:

// the schema
const { Nohm } = require("nohm");

Nohm.setPrefix("bus");
const Pet = Nohm.model("Pet", {
  properties: {
    id: { type: "string", index: true, unique: true }, // vin
    ns: { type: "string", index: true }
  }
});

const pet = new Pet();

 // set some properties
 pet.property({
      id: "a-given-id-not-auto-generated",
      ns: "/Gondor",
 });

We find that model will be stored with an extra auto generated uuid in the key.

like

nohm:hash:Pet:c8792349-sdf234234-dsfs-234ssdfsf-234234

And when we load it

Pet.load("a-given-id-not-auto-generated");

it throw not found error

[maritz]

I’m not exactly sure what you mean.

Option 1

You want some other method than uuid or incremental ids for all your ids for a model.

This is covered by idGenerators.

Option 2

You have some specific (and rare) cases where you don’t want the default generation to happen when creating new instances and you already have an ID that you want to use for it and you are either sure it doesn’t already exist or you are fine with updating an old one if it does exist.

const Pet = Nohm.model("Pet", {
  properties: {
    ns: { type: "string", index: true }
  }
});

const pet = new Pet();

pet.id = 'foo-bar';
pet.property({
  ns: "/Gondor",
});

await pet.save();

await Pet.load('foo-bar'); // should return the pet we just created.

// HOWEVER!
// if you then do this:

const pet2 = new Pet();

pet2.id = 'foo-bar';
pet2.property({
  ns: "/Mordor",
});

await pet2.save(); // this UPDATES the "pet1" we created earlier, because the id is already in the database.

Again: WARNING! You are completely responsible for the ids this way and have to make sure that when you create a new instance the id you pass is available at the time of saving the object! For example the built-in incremental id generator increments before saving. Thus no 2 saves can ever have the same id, no matter how concurrent. It has the downside that if something goes very wrong, it may skip numbers, but that’s more acceptable than accidentally updating when you want to create.

If you don’t set the id before saving a new instance, it will fall back to creating a uuid.

[zzswang]

@maritz

Thank you. option 2 is exactly what we need.

We use Redis to save some data which comes from other services. These modes will have ids, and are used in api call, like /pets/:petId.