feat: allow methods to control strictObjectIDCoercion

[virkt25]

Description

• This PR came about as my work on loopback4-example-shopping. For relations, we need to be able to enable strictObjectIDCoercion for those methods only. This PR allows the flag to be passed in from a method instead of just being set on the model.

Related issues

• connect to <link_to_referenced_issue>

Checklist

• New tests added or existing tests modified to cover all changes
• Code conforms with the style
  guide

[b-admike]

Nice work @virkt25. Can we add tests for this new behaviour?

[virkt25]

Nice work @virkt25. Can we add tests for this new behaviour?

Tried adding tests as follows in /test/objectid.test.js:

  it('coerces ObjectID', function() {
    const coercedId = db.connector.coerceId(Book, '52fcef5c0325ace8dcb7a0bd');
    coercedId.should.be.an.instanceOf(db.ObjectID);
  });

  it('given strictObjectIDCoercion: true, does not coerce ObjectID', function() {
    const coercedId = db.connector.coerceId(Book, '52fcef5c0325ace8dcb7a0bd', {strictObjectIDCoercion: true});
    coercedId.should.be.an.instanceOf(String);
  });

But I keep getting the following errors:

1) ObjectID
       coerces ObjectID:
     TypeError: Cannot read property 'idName' of undefined
      at MongoDB.Connector.idName (node_modules/loopback-connector/lib/connector.js:161:35)
      at MongoDB.coerceId (lib/mongodb.js:483:21)
      at Context.<anonymous> (test/objectid.test.js:58:36)

  2) ObjectID
       given strictObjectIDCoercion: true, does not coerce ObjectID:
     TypeError: Cannot read property 'idName' of undefined
      at MongoDB.Connector.idName (node_modules/loopback-connector/lib/connector.js:161:35)
      at MongoDB.coerceId (lib/mongodb.js:483:21)
      at Context.<anonymous> (test/objectid.test.js:63:36)

Any idea how to add tests? There are no existing tests covering this flag / the coerceId, isObjectIdProperty functions.

[jannyHou]

@virkt25 I think you can provide the model name as string instead of a model constructor to get the tests pass:

 it('coerces ObjectID', function() {
    // note it is 'Book' not Book
    const coercedId = db.connector.coerceId('Book', '52fcef5c0325ace8dcb7a0bd');
    coercedId.should.be.an.instanceOf(db.ObjectID);
  });

[bajtos]

Here is the code throwing the error (assuming your stack trace is from the latest version of loopback-connector as seen on GitHub):

https://github.com/strongloop/loopback-connector/blob/dbfebb845b9eba321353e99e080a22f77df0c110/lib/connector.js#L160-L162

Connector.prototype.idName = function(model) {
  return this.getDataSource(model).idName(model);
};

I strongly suspect that in the test you tried to wrote, there was no model defined on the datasource with the name matching the string you passed to coerceId.

What you need to do in your test:

1. Create a new model on the datasource backed by the connector under the test. DataSource provides API for creating new models - see DataSource.prototype.createModel.

2. Pass the name of the newly created model to coerceId function.

 it('coerces ObjectID', function() {
  const Book = db.createModel('Book' /*, {properties...}, {settings...}*/);
  const coercedId = db.connector.coerceId(Book.modelName, '52fcef5c0325ace8dcb7a0bd');
  coercedId.should.be.an.instanceOf(db.ObjectID);
});

I am typing this information from my head, it may not be entirely accurate. Sorry if it does not work out of the box!

[jannyHou]

nice! LGTM