json_build_array and json_build_object functions

server/functions/framework/overloads.go

@@ -86,9 +86,21 @@ func (o *Overloads) overloadsForParams(numParams int) []Overload {
 			// parameter count from the target parameter count to obtain the additional parameter count.
 			firstValueAfterVariadic := variadicIndex + 1 + (numParams - len(params))
 			copy(extendedParams[firstValueAfterVariadic:], params[variadicIndex+1:])
-			// ToArrayType immediately followed by BaseType is a way to get the base type without having to cast.
-			// For array types, ToArrayType causes them to return themselves.
-			variadicBaseType := overload.GetParameters()[variadicIndex].ToArrayType().ArrayBaseType()
+			paramType := overload.GetParameters()[variadicIndex]
+
+			var variadicBaseType *pgtypes.DoltgresType
+
+			// special case: anyArray takes any args, pass as is
+			if paramType == pgtypes.AnyArray {
+				for variadicParamIdx := 0; variadicParamIdx < 1+(numParams-len(params)); variadicParamIdx++ {
+					variadicBaseType = pgtypes.AnyElement
+				}
+			} else {
+				// ToArrayType immediately followed by BaseType is a way to get the base type without having to cast.
+				// For array types, ToArrayType causes them to return themselves.
+				variadicBaseType = paramType.ToArrayType().ArrayBaseType()
+			}
+
 			for variadicParamIdx := 0; variadicParamIdx < 1+(numParams-len(params)); variadicParamIdx++ {
 				extendedParams[variadicParamIdx+variadicIndex] = variadicBaseType
 			}

server/functions/json.go

@@ -15,6 +15,7 @@
 package functions
 
 import (
+	"fmt"
 	"unsafe"
 
 	"github.com/dolthub/go-mysql-server/sql"
@@ -30,6 +31,8 @@ func initJson() {
 	framework.RegisterFunction(json_out)
 	framework.RegisterFunction(json_recv)
 	framework.RegisterFunction(json_send)
+	framework.RegisterFunction(json_build_array)
+	framework.RegisterFunction(json_build_object)
 }
 
 // json_in represents the PostgreSQL function of json type IO input.
@@ -83,3 +86,50 @@ var json_send = framework.Function1{
 		return []byte(val.(string)), nil
 	},
 }
+
+// json_build_array represents the PostgreSQL function json_build_array.
+var json_build_array = framework.Function1{
+	Name:       "json_build_array",
+	Return:     pgtypes.Json,
+	Parameters: [1]*pgtypes.DoltgresType{pgtypes.AnyArray},
+	Variadic:   true,
+	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val1 any) (any, error) {
+		inputArray := val1.([]any)
+		json, err := json.Marshal(inputArray)
+		return string(json), err
+	},
+}
+
+// json_build_object represents the PostgreSQL function json_build_object.
+var json_build_object = framework.Function1{
+	Name:       "json_build_object",
+	Return:     pgtypes.Json,
+	Parameters: [1]*pgtypes.DoltgresType{pgtypes.AnyArray},
+	Variadic:   true,
+	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val1 any) (any, error) {
+		inputArray := val1.([]any)
+		if len(inputArray)%2 != 0 {
+			return nil, sql.ErrInvalidArgumentNumber.New("json_build_object", "even number of arguments", len(inputArray))
+		}
+		jsonObject := make(map[string]any)
+		var key string
+		for i, e := range inputArray {
+			if i%2 == 0 {
+				var ok bool
+				key, ok = e.(string)
+				if !ok {
+					// TODO: This isn't correct for every type we might use as a value. To get better type info to transform
+					//  every value into its string format, we need to pass detailed arg type info for the vararg params (the
+					//  unused param in the function call).
+					key = fmt.Sprintf("%v", e)
+				}
+			} else {
+				jsonObject[key] = e
+				key = ""
+			}
+		}
+
+		json, err := json.Marshal(jsonObject)
+		return string(json), err
+	},
+}

server/types/array.go

@@ -62,3 +62,10 @@ func CreateArrayTypeFromBaseType(baseType *DoltgresType) *DoltgresType {
 		CompareFunc:   toFuncID("btarraycmp", toInternal("anyarray"), toInternal("anyarray")),
 	}
 }
+
+// LogicalArrayElementTypes is a map of array element types for particular array types where the logical type varies
+// from the declared type, as needed. Some types that have a NULL element for pg_catalog compatibility have a logical
+// type that we need during analysis for function calls.
+var LogicalArrayElementTypes = map[id.Type]*DoltgresType{
+	toInternal("anyarray"): AnyElement,
+}

server/types/type.go

@@ -109,10 +109,20 @@ func (t *DoltgresType) ArrayBaseType() *DoltgresType {
 	if !t.IsArrayType() {
 		return t
 	}
-	elem, ok := IDToBuiltInDoltgresType[t.Elem]
+
+	var elem *DoltgresType
+	var ok bool
+
+	elem, ok = IDToBuiltInDoltgresType[t.Elem]
 	if !ok {
-		panic(fmt.Sprintf("cannot get base type from: %s", t.Name()))
+		// Some array types have no declared element type for pg_catalog compatibilty, but still have a logical type
+		// we return for analysis
+		elem, ok = LogicalArrayElementTypes[t.ID]
+		if !ok {
+			panic(fmt.Sprintf("cannot get base type from: %s", t.Name()))
+		}
 	}
+
 	newElem := *elem.WithAttTypMod(t.attTypMod)
 	return &newElem
 }
@@ -433,7 +443,8 @@ func (t *DoltgresType) IoOutput(ctx *sql.Context, val any) (string, error) {
 
 // IsArrayType returns true if the type is of 'array' category
 func (t *DoltgresType) IsArrayType() bool {
-	return t.TypCategory == TypeCategory_ArrayTypes && t.Elem != id.NullType
+	return (t.TypCategory == TypeCategory_ArrayTypes && t.Elem != id.NullType) ||
+		(t.TypCategory == TypeCategory_PseudoTypes && t.ID.TypeName() == "anyarray")
 }
 
 // IsEmptyType returns true if the type is not valid.

testing/go/functions_test.go

@@ -962,6 +962,51 @@ func TestSystemInformationFunctions(t *testing.T) {
 	})
 }
 
+func TestJsonFunctions(t *testing.T) {
+	RunScripts(t, []ScriptTest{
+		{
+			Name: "json_build_array",
+			Assertions: []ScriptTestAssertion{
+				{
+					Query:    `SELECT json_build_array(1, 2, 3);`,
+					Cols:     []string{"json_build_array"},
+					Expected: []sql.Row{{`[1,2,3]`}},
+				},
+				{
+					Query:    `SELECT json_build_array(1, '2', 3);`,
+					Cols:     []string{"json_build_array"},
+					Expected: []sql.Row{{`[1,"2",3]`}},
+				},
+				{
+					Query:    `SELECT json_build_array();`,
+					Skip:     true, // variadic functions can't handle 0 arguments right now
+					Cols:     []string{"json_build_array"},
+					Expected: []sql.Row{{`[]`}},
+				},
+			},
+		},
+		{
+			Name: "json_build_object",
+			Assertions: []ScriptTestAssertion{
+				{
+					Query:    `SELECT json_build_object('a', 2, 'b', 4);`,
+					Cols:     []string{"json_build_object"},
+					Expected: []sql.Row{{`{"a":2,"b":4}`}},
+				},
+				{
+					Query:       `SELECT json_build_object('a', 2, 'b');`,
+					ExpectedErr: "even number",
+				},
+				{
+					Query:    `SELECT json_build_object(1, 2, 'b', 3);`,
+					Cols:     []string{"json_build_object"},
+					Expected: []sql.Row{{`{"1":2,"b":3}`}},
+				},
+			},
+		},
+	})
+}
+
 func TestArrayFunctions(t *testing.T) {
 	RunScripts(t, []ScriptTest{
 		{