Use of ColumnSet for setting up "SELECT" or "RETURNING" clauses

[sebastorama]

Given that I have the following ColumnSet:

    const returnCS = new pgp.helpers.ColumnSet([
      'ingredientId',
      'recipeId',
      {
        name: 'inclusionRatio',
        cast: 'float',
      },
      {
        name: 'pricePerKg',
        cast: 'float',
      },
    ]);

The important bit being the cast: 'float' part on the 2 numeric fields. Is there a way to use this inside a SELECT or RETURNING clause to produce something like this: "ingredientId", "recipeId", "inclusionRatio"::float, "pricePerKg"::float ?

using "returnCS.names" and the name filter will produce the column fields, but without the ::float bit. Is ColumnSet intended more for insert/update statements?

[vitaly-t]

ColumnSet is intended for the functions provided within the helpers namespace. "Select" isn't there, and not meant to be.

If you want to reuse ColumnSet in that manner, you can create a function that will generate such syntax:

function listColumns(cs : ColumnSet) : string {
    return cs.columns.map(c => c.escapedName + (c.cast ? '::' + c.cast : '')).join(', ');
}

[sebastorama]

Thanks a lot for your work and support!

Sidetracking, but adjacent to this, I noticed that numeric fields come to JS land as strings (probably the pg driver itself does that, floats comes as number). Is there a more elegant way of getting that as numbers? I thought of doing "parseFloats" on the returned objects.

(The thinking behind this probably is due to possible loss of precision on an IEEE 754 representation of floats, so the user is making that decision knowingly the possible side-effects)

[vitaly-t]

I noticed that numeric fields come to JS land as strings (probably the pg driver itself does that, floats comes as number). Is there a more elegant way of getting that as numbers? I thought of doing "parseFloats" on the returned objects.

Types conversion is managed by pg-types, which you can access via pgp.pg.types. See also this question.