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Adding support for arrays #380

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arjen-ag5
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Hello,

I'm working on support for arrays in go-jet. I was wondering if this is a feature that is considered in the long run and if it maybe merged into upstream in the long term. I'd like to show the progress I made so far and if it's any use trying to get it merged at all. If not I will not spend any effort in making it work with the different database types. Currently I only implemented postgres.

I can see from the Range support that is added earlier that the types from the pgtypes packages are being used. I took this into consideration for use as the SQL types in the generated table types. But the pgtypes.Array* structs are tailored to represent the internal representation of the postgresql array types. In constrast to the pq.Array* types which are much more user friendly, thats why I chose to use the latter.

@arjen-ag5 arjen-ag5 changed the title Adding support for (string) arrays Adding support for arrays Sep 4, 2024
@go-jet
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go-jet commented Sep 7, 2024

Hi @arjen-ag5, thanks for starting the work on arrays.

if column.DataType.Dimensions > 1 {
return ""
}

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Multi dimensional arrays are just arrays containing other arrays. In our case Array[Array[StringExpression]]. But it is fine with PR to go with single dimension arrays only.

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You're right, but since we don't have a good model type yet, I haven't included this case yet

case "bigint[]":
return pq.Int64Array{}
case "text[]", "jsonb[]", "json[]":
return pq.StringArray{}
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I'm fine using pq types for one dimensional arrays. Maybe pgtype can be used for multi dimensional arrays.
Other types as well, time, date, etc...

typeName := columnMetaData.DataType.Name
columnName := columnMetaData.Name

if columnMetaData.DataType.Kind == metadata.ArrayType {
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Why not add a case switch for each of the array types, as it is already done for other types?

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I added a new sqlArrayToColumnType to convert a type to an array type. The function switches on the type name without the [] suffix because you would have to add infinite brackets for multidimensional arrays.

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When I think about it again it makes sense to separate arrays from sqlToColumnType. Since every postgres type can be element of array([]bool, []point, []timestamp, etc...), sql builder array type can be constructed with just sqlToColumnType:

columnType = sqlToColumnType(strings.TrimSuffix(typeName, "[]")) + "Array"

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This can lead to incorrectly generated code, because this PR does not support DateArray for example. What's your opinion on this?

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It can be supported with one line type DateArray Array[DateExpression]. For model type we can fallback to string if there is no pq date array type.

@@ -190,8 +222,7 @@ func getSqlBuilderColumnType(columnMetaData metadata.Column) string {
case "numrange":
return "NumericRange"
default:
fmt.Println("- [SQL Builder] Unsupported sql column '" + columnMetaData.Name + " " + columnMetaData.DataType.Name + "', using StringColumn instead.")
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Even if we add array types, there still gonna be some unsupported types, so warning message can remain.

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The warning is handled in the caller

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Aha, I see. Maybe we an error would be more in go style.

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@arjen-ag5 arjen-ag5 Sep 9, 2024

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How about?

// sqlToColumnType maps the type of a SQL column type to a go jet sql builder column. The second return value returns 
// whether the given type is supported.
func sqlToColumnType(typeName string) (string, bool) {

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Yeah, that is fine as well.

package jet

// ArrayExpression interface
type ArrayExpression[E Expression] interface {
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Maybe just Array[E Expression], so it follows naming convention with Range. Also Expression would repeat twice in the name.

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👍 Done

CONCAT(rhs ArrayExpression[E]) ArrayExpression[E]
CONCAT_ELEMENT(E) ArrayExpression[E]

AT(expression IntegerExpression) Expression
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AT should return element type E. Take a look at rangeTypeCaster how to extract element type.

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Done

@@ -316,6 +316,32 @@ func (s *complexExpression) serialize(statement StatementType, out *SQLBuilder,
}
}

type arraySubscriptExpression struct {
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This is the old way to construct custom expression. The new and easier way is using CustomExpression and Token. In this case: CustomExpression(array, Token("["), index, Token("]")).

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Done

literalExpressionImpl
}

func UnsafeArray[E LiteralExpression](values []interface{}) ArrayExpression[E] {
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Why is it needed?

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@arjen-ag5 arjen-ag5 Sep 7, 2024

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Was experimenting around, forgot to remove it. Gone now

literalExpressionImpl
}

func Int64Array(values []int64) ArrayExpression[IntegerExpression] {
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Can be done without new literal types. Some of these files need some cleaning.

func Int64Array(values []int64) ArrayExpression[IntegerExpression] {
    return ArrayExp[IntegerExpression](literal(pq.Int64Array(values))
}

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Cleanedup

@@ -253,6 +255,19 @@ func argToString(value interface{}) string {
}
}

func stringArrayQuote(val []string) string {
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Maybe we can use pq.StringArray{}.Value() instead, and cast first returned value to string.

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Like this?

func stringArrayQuote(val []string) string {
	// We'll rely on the internals of pq2.StringArray here. We know it will never return an error, and the returned
	// value is a string
	dv, _ := pq2.StringArray(val).Value()
	return dv.(string)
}

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Yeah, exactly.

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Done

@@ -16,6 +16,9 @@ type StringExpression interface {
BETWEEN(min, max StringExpression) BoolExpression
NOT_BETWEEN(min, max StringExpression) BoolExpression

ANY_EQ(rhs ArrayExpression[StringExpression]) BoolExpression
ALL_EQ(rhs ArrayExpression[StringExpression]) BoolExpression

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@go-jet go-jet Sep 7, 2024

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If we add ANY_EQ, we would also need to add, for each of the types, NOT_EQ_ANY, LT_ANY, LT_EQ_ANY, etc... This would lead to number of methods explosion.

Simpler way would be to have ANY and ALL as generic functions:

func ANY[E Expression](array Array[E]) E {
    // check rangeTypeCaster
}

Then we can write for any type:

Table.SomeStringColumn.EQ(ANY(Table.StringArrayColumn))

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Yeah, that makes sense. I'll change that

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Done

postgres/cast.go Outdated
@@ -45,6 +45,10 @@ type cast interface {
AS_INTERVAL() IntervalExpression
}

type castArray interface {
AS_STRING() jet.ArrayExpression[StringExpression]
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Why separate interface?

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Was left over cruft from experimentation, removed it

@@ -967,26 +969,25 @@ func TestScanIntoCustomBaseTypes(t *testing.T) {
ReplacementCost MyFloat64
Rating *model.MpaaRating
LastUpdate MyTime
SpecialFeatures *MyString
SpecialFeatures MyStringArray
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If SpecialFeatures is pq.StringArray you wouldn't need to exclude SpecialFeatures column bellow.

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@arjen-ag5 arjen-ag5 Sep 9, 2024

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With the type alias like so:

type MyStringArray pq.StringArray

The MyStringArray type does not implement Scanner. The QRM will then see it as a slice because that's what pq.StringArray is and try to apply it's row mapping into the slice. Therefore it will always be null.

Adding a method like this would work:

func (a *MyStringArray) Scan(src interface{}) error {
	x := (*pq.StringArray)(a)
	return x.Scan(src)
}

What do you think?

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No, I'm meant without defining a type, either by realiasing or not using new type at all:

type MyStringArray = pq.StringArray // note '=', MyStringArray now retains Scan method

or

	type film struct {
		FilmID          MyUint16 `sql:"primary_key"`
		Title           MyString
		Description     *MyString
		ReleaseYear     *MyInt16
		LanguageID      MyUint8
		RentalDuration  MyUint8
		RentalRate      MyFloat32
		Length          *MyUint32
		ReplacementCost MyFloat64
		Rating          *model.MpaaRating
		LastUpdate      MyTime
		SpecialFeatures *MyString
		SpecialFeatures pq.StringArray
	}

@@ -2,6 +2,7 @@ package postgres

import (
"database/sql"
"github.com/lib/pq"
"testing"
"time"

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As for testing, maybe we can have a new array only table, similar to what's already been done for range tests.

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Note that test files are in separate repo: https://github.com/go-jet/jet-test-data

}

func ARRAY_APPEND[E Expression](arr Array[E], el E) Array[E] {
return arrayTypeCaster[E](arr, Func("array_append", arr, el))
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@go-jet go-jet Sep 22, 2024

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uppercase "array_append".

@@ -11,6 +11,11 @@ func Bool(value bool) BoolExpression {
return CAST(jet.Bool(value)).AS_BOOL()
}

// BoolArray creates new bool array literal expression
func BoolArray(elements []bool) BoolArrayExpression {
return jet.BoolArray(elements)
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We'll probably need an explicit cast here as well, since cockroachdb tends to have problem with untyped parameters.

@sarthakjdev
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hey, would this be merged any time sooner? Have been using go-jet for a production project (https://wapikit.com) and just noticed, it does not supports arrays yet.

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3 participants