Expose node-postgres (pg module) directly on the connector

[zero5100]

Description

The problem we ran across is that brianc/node-postgres parses the PG DATE type into JavaScript Dates by default instead of strings. To me, this doesn't make much sense since JS doesn't have a date-only type, but it what they decided to go with. They provide the ability to change how the values are parsed for each PG data type using types.setTypeParser (see related issue), but as far as I can tell there is no easy way to change the parser on the pg module instance that the loopback connector is using.

To make things easier from our end we configured our date model property as a String so that we can easily and accurately save dates in string form. (e.g. { exampleDate: '2016-12-20' }).

"exampleDate": {
  "type": "String",
  "required": true,
  "length": null,
  "precision": null,
  "scale": null,
  "postgresql": {
    "columnName": "example_date",
    "dataType": "date",
    "dataLength": null,
    "dataPrecision": null,
    "dataScale": null,
    "nullable": "NO"
  }
}

The problem then is that we still get dates back from the ORM as JS Dates (e.g. Tue Dec 20 2016 00:00:00 GMT-0600 (CST)). This technically has the correct date portion, but when formatting it as a string there is the potential for the day to shift forward or backward because of the time in regard to the time zone if care isn't taken. If the date that was returned was Tue Dec 19 2016 18:00:00 GMT-0600 (CST) instead it may be manageable since it is technically the same point in time as the date string of '2016-12-20' (assumed to be at midnight UTC), but the way it currently works is dangerous in our case. This is for a financial system so there needs to be as small of room for error as possible.

By exposing the pg instance as "postgresql" on the connector, we are able to configure the type parser in our application like so.

(server.js or wherever)

var pgDs = app.datasources.PG_DB;
if (pgDs && pgDs.connector && pgDs.connector.postgresql) {

  // Parse the postgres DATE type as a string instead of a date
  pgDs.connector.postgresql.types.setTypeParser(1082, function(val) { return String(val) });
}

I am sure there is a better way to accomplish this so I am open to feedback for other ways to solve this issue. I would be up for contributing some sort of parser configuration system if there was interest in it. This fix got us going but there may be concerns with exposing the pg instance to the application that I am not aware of.

Thanks in advance.

Related issues

(Parsing dates as strings over on the pg module issues)
brianc/node-postgres#285

Checklist

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

[slnode]

Can one of the admins verify this patch? To accept patch and trigger a build add comment ".ok\W+to\W+test."

[slnode]

Can one of the admins verify this patch?

[slnode]

Can one of the admins verify this patch?

[slnode]

Can one of the admins verify this patch?

[ssh24]

@zero5100 Could you please your branch?

[ssh24]

@slnode ok to test

[ssh24]

@zero5100 I have rebased the branch for you. Could you please add some unit tests to go with the fix?

[zero5100]

@ssh24 Thank you. I can create a simple test that just makes sure that the newly exposed object is defined. Which test file should it go in?

[ssh24]

@zero5100 ./test/postgresql.test.js

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been closed due to continued inactivity. Thank you for your understanding. If you believe this to be in error, please contact one of the code owners, listed in the CODEOWNERS file at the top-level of this repository.