New find select object api should support false values as expected

[cduff]

Feature Description

The Problem

As per https://typeorm.io/#/find-options/basic-options, typeorm now supports syntax like:

userRepository.find({
    select: {
        firstName: true,
        lastName: true,
    },
})

However, if you change one of the values to false, like:

userRepository.find({
    select: {
        firstName: true,
        lastName: false, // note false
    },
})

Then it makes no difference. lastName is still selected which does not seem intuitive.

However, if the value is specified as undefined then the field will not be selected:

userRepository.find({
    select: {
        firstName: true,
        lastName: undefined, // note undefined
    },
})

It would be great if false was handled intuitively so that simple boolean conditions can be specified for conditional selection.

Note that the relations option has a similar interface and it does handle false values as expected.

The Solution

Could be simple as changing the following line:

typeorm/src/query-builder/SelectQueryBuilder.ts

Line 3586 in 68a5c23

if (select[key] === undefined) continue

to:

if (!select[key]) continue;

???

Considered Alternatives

undefined can be specified instead of false but this complicates code for conditional selects.

The select implementation is also inconsistent with the relations implementation which does handle false values as expected.

Additional Context

The new select and relations API was recently released in https://github.com/typeorm/typeorm/releases/tag/0.3.0.

Relevant Database Driver(s)

n/a

Are you willing to resolve this issue by submitting a Pull Request?

• ✖️ Yes, I have the time, and I know how to start.
• ✖️ Yes, I have the time, but I don't know how to start. I would need guidance.
• ✖️ No, I don’t have the time, but I can support (using donations) development.
• ✅ No, I don’t have the time and I’m okay to wait for the community / maintainers to resolve this issue.

[pleerock]

I suggest to simply do it as:

 if (select[key] === undefined || select[key] === false) continue 

and add test for this change. Simply to contribute.