流星Sub / Pub with Simulation，其中发布缓慢更新

Question

I have a pub that wraps and external API. Client subs the external api pub. There is a 'ACTIVATE' button they can push to activate a billing method. Button calls an update method that updates the collection. The pub updates the external api. Simulation runs and updates the client collection. Button changes to 'DEACTIVATE' as expected. This is where the issue comes in. The external api takes some time to return with the updated doc. Within 100-200ms of the button turning to 'DEACTIVATE' it will flip back to 'ACTIVATE' and then 500ms latter back to 'DEACTIVATE' where it should be assuming there were no issues with the external api.

I'm sure I could come up with some hacky solution to deal with this in the client but wondering if there is a way to tell the simulation/client collection that the pub is slow and to not update quite as often? Thus, giving the pub/external api more time to complete it's updates.

Answer 1

This turned out to be really simple.

Client side simulation alone is not enough. The trick is to do server side simulation as well. To accomplish this first setup a hook to the Meteor.publish this object something like this.

_initServer() {
  if (Meteor.isServer) {
    console.log(`Server initializing external collection "${this.name}"`)
    let self = this

    Meteor.publish(this.name, function (selector, options) {
      check(selector, Match.Optional(Match.OneOf(undefined, null, Object)))
      check(options, Match.Optional(Match.OneOf(undefined, null, Object)))

      self.publication = this
      self._externalApi.fetchAll()
        .then((docs)=>docs.forEach((doc)=>this.added(self.name, doc._id, doc)))
        .then(()=>this.ready())
        // todo handle error
        .catch((error)=>console.error(`${self.name}._initServer: self._externalApi.fetchAll`, error))
    })
  }
}

Then in your update function you can simulate on both the client and server like so:

  this.update = new ValidatedMethod({
    name: `${self.name}.update`,
    validate: (validators && validators.update) ? validators.update : self.updateSchema.validator({clean: true}),
    run(doc) {
      console.log(`${self.name}.update `, doc)
      if (Meteor.isServer && self._externalApi.update) {
        // server side simulation
        self.changed(doc)

        self._externalApi.update(doc._id, doc)
          .then(self.changed)
          .catch((error)=>handleError(`${self.name}.update`, 'externalApi.update', error))
      } else {
        // client side simulation
        self.collection.update(doc._id, {$set: doc})
      }
    },
  })

Apologizes if this is over simplified these examples are from a large library we use for external api's.