fix(pgdialect): postgres syntax errors for pointers and slices #877

[rfarrjr]

Addresses issue identified in #877.

New tests added for pointers to slice and slice of pointer elements including arrays of JSONB columns.

[j2gg0s]

What does it mean to use both jsonb and array together?
I think PostgreSQL will handle the JSONB type, and we only need to consider JSONB when inserting and reading data?

[rfarrjr]

Yes. PostgreSQL doesn't actually support a JSONB array directly, but rather includes several functions (jsonb_array_elements) for working with a JSONB arrays on a JSONB column. Can read more here.

[j2gg0s]

Thanks your PR, it seems like it could help us a lot.

I have a strange example, not sure if it’s appropriate.
The model:

type Location struct {
	ID string `bun:"type:uuid,pk"`

	// Users []User `bun:"type:jsonb,array"`
	UserIDs []UserID `bun:"type:text[]"`
}

type UserID struct {
	ID string
}

func (u UserID) AppendQuery(fmter schema.Formatter, b []byte) ([]byte, error) {
        v := []byte(`"` + u.ID + `"`)
        return append(b, v...), nil
}

var _ schema.QueryAppender = (*UserID)(nil)

Run with output:

[bun]  12:21:27.085   DROP TABLE           49.112ms  DROP TABLE IF EXISTS "locations" CASCADE
[bun]  12:21:27.102   CREATE TABLE         16.262ms  CREATE TABLE "locations" ("id" uuid NOT NULL, "user_i_ds" text[], PRIMARY KEY ("id"))
[bun]  12:21:27.109   INSERT                7.047ms  INSERT INTO "locations" ("id", "user_i_ds") VALUES ('a2cd66d9-c5c6-4b06-a0a9-da2b4ed85960', '["foo","bar"]')       pgdriver.Error: ERROR: malformed array literal: "["foo","bar"]" (SQLSTATE=22P02)
panic: ERROR: malformed array literal: "["foo","bar"]" (SQLSTATE=22P02)

[j2gg0s]

Is this meant to handle JSONB? But why would the JSONB type end up being processed here?

[rfarrjr]

These are needed to format a JSON array since the underlying column is just JSONB.

I think I need to add a check here to ignore this if the type is no JSONB or if the elemType implement query appender to handle your example above correctly. Will add that test and fix.

[Aoang]

I believe this is intended to enhance structural support for "text[]", but the underlying logic appears to be somewhat perplexing. Perhaps I am not fully grasping it yet.

It may be beneficial for you to review the following link: https://github.com/FlowerLab/sorbifolia/blob/main/bunpgd/datatype/typ_array.go to determine if it aligns with your objectives.

[rfarrjr]

This PR addresses a couple of things:

1. Handle array of structs mapping to a JSONB column, which does enhance the option of serializing/deserializing structs into a text[] type.

2. ,array sql type detection doesn't handle arrays of pointers with specifying the type. i.e.

type Person {
   Names []*string `bun:",array"`  
}

3. Property quoting strings in an array when using []*string

[j2gg0s]

In my understanding, this PR aims to accomplish two things:

1. Fix bug when Go type is []*string and the PostgreSQL's type is text[]
2. Support append&scan, when Go type is []struct and type PostgreSQL's type is array

For 1, this should be fixed, and we can also handle other basic types along the way.

For 2, I don’t see the necessity to support this feature for now.
Most of the time, we use text or JSONB in PostgreSQL for storage.

[rfarrjr]

This actually got me thinking, so I tried the following and it is functional. Could be worth updating the documentation to show how to handle arrays when using jsonb.

type Model struct {
  ID        int64    `bun:",pk,autoincrement"`
  Items     []Item   `bun:",type:jsonb"`
  ItemsP    []*Item  `bun:",type:jsonb"`
}

I will back out the enhancement changes and just leave the fixes