Meteor Collections Simpleschema, autovalue depending on other field values

Question

i have three fields in a Collection:

Cards.attachSchema(new SimpleSchema({
  foo: {
    type: String,
  },
  bar: { 
    type: String,
  },
  foobar: {
    type: String,
    optional: true,
    autoValue() { 
      if (this.isInsert && !this.isSet) {
        return `${foo}-${bar}`;
      }
    },
  },
);

So i want to have the field foobar to get as auto(or default) value, if not explicitly set, to return both values of foo and bar. Is this possible?

Answer 1

You may use the this.field() method inside your autoValue function:

Cards.attachSchema(new SimpleSchema({
  foo: {
    type: String,
  },
  bar: { 
    type: String,
  },
  foobar: {
    type: String,
    optional: true,
    autoValue() { 
      if (this.isInsert && !this.isSet) {
        const foo = this.field('foo') // returns an obj
        const bar = this.field('bar') // returns an obj
        if (foo && foo.value && bar && bar.value) {
          return `${foo.value}-${bar.value}`;
        } else {
          this.unset()
        }
      }
    },
  },
);

Related reading: https://github.com/aldeed/simple-schema-js#autovalue

However, you could also solve this by using a hook on the insert method of your collection. There you could assume the values foo and bar to be present, because your schema requires them:

Cards.attachSchema(new SimpleSchema({
  foo: {
    type: String,
  },
  bar: { 
    type: String,
  },
  foobar: {
    type: String,
    optional: true,
  },
);



Cards.after.insert(function (userId, doc) {
   // update the foobar field depending on the doc's 
   // foobar values
});