draft: add invoke interface to postgres source

internal/sources/postgres/postgres.go

@@ -23,6 +23,7 @@ import (
 	"github.com/goccy/go-yaml"
 	"github.com/googleapis/genai-toolbox/internal/sources"
 	"github.com/googleapis/genai-toolbox/internal/util"
+	"github.com/googleapis/genai-toolbox/internal/tools"
 	"github.com/jackc/pgx/v5/pgxpool"
 	"go.opentelemetry.io/otel/trace"
 )
@@ -92,8 +93,29 @@ func (s *Source) SourceKind() string {
 	return SourceKind
 }
 
-func (s *Source) PostgresPool() *pgxpool.Pool {
-	return s.Pool
+func (s *Source) RunSQL(ctx context.Context, statement string, params any) (any, error) {
+	sliceParams := params.(tools.ParamValues).AsSlice()
+	results, err := s.Pool.Query(ctx, statement, sliceParams...)
+	if err != nil {
+		return nil, fmt.Errorf("unable to execute query: %w", err)
+	}
+
+	fields := results.FieldDescriptions()
+
+	var out []any
+	for results.Next() {
+		v, err := results.Values()
+		if err != nil {
+			return nil, fmt.Errorf("unable to parse row: %w", err)
+		}
+		vMap := make(map[string]any)
+		for i, f := range fields {
+			vMap[f.Name] = v[i]
+		}
+		out = append(out, vMap)
+	}
+
+	return out, nil
 }
 
 func initPostgresConnectionPool(ctx context.Context, tracer trace.Tracer, name, host, port, user, pass, dbname string, queryParams map[string]string) (*pgxpool.Pool, error) {

internal/tools/postgres/postgressql/postgressql.go

@@ -24,7 +24,6 @@ import (
 	"github.com/googleapis/genai-toolbox/internal/sources/cloudsqlpg"
 	"github.com/googleapis/genai-toolbox/internal/sources/postgres"
 	"github.com/googleapis/genai-toolbox/internal/tools"
-	"github.com/jackc/pgx/v5/pgxpool"
 )
 
 const kind string = "postgres-sql"
@@ -44,7 +43,7 @@ func newConfig(ctx context.Context, name string, decoder *yaml.Decoder) (tools.T
 }
 
 type compatibleSource interface {
-	PostgresPool() *pgxpool.Pool
+	RunSQL(ctx context.Context, statement string, params any) (any, error)
 }
 
 // validate compatible sources are still compatible
@@ -101,7 +100,7 @@ func (cfg Config) Initialize(srcs map[string]sources.Source) (tools.Tool, error)
 		AllParams:          allParameters,
 		Statement:          cfg.Statement,
 		AuthRequired:       cfg.AuthRequired,
-		Pool:               s.PostgresPool(),
+		source:             s,
 		manifest:           tools.Manifest{Description: cfg.Description, Parameters: paramManifest, AuthRequired: cfg.AuthRequired},
 		mcpManifest:        mcpManifest,
 	}
@@ -119,7 +118,7 @@ type Tool struct {
 	TemplateParameters tools.Parameters `yaml:"templateParameters"`
 	AllParams          tools.Parameters `yaml:"allParams"`
 
-	Pool        *pgxpool.Pool
+	source      compatibleSource
 	Statement   string
 	manifest    tools.Manifest
 	mcpManifest tools.McpManifest
@@ -136,28 +135,7 @@ func (t Tool) Invoke(ctx context.Context, params tools.ParamValues, accessToken
 	if err != nil {
 		return nil, fmt.Errorf("unable to extract standard params %w", err)
 	}
-	sliceParams := newParams.AsSlice()
-	results, err := t.Pool.Query(ctx, newStatement, sliceParams...)
-	if err != nil {
-		return nil, fmt.Errorf("unable to execute query: %w", err)
-	}
-
-	fields := results.FieldDescriptions()
-
-	var out []any
-	for results.Next() {
-		v, err := results.Values()
-		if err != nil {
-			return nil, fmt.Errorf("unable to parse row: %w", err)
-		}
-		vMap := make(map[string]any)
-		for i, f := range fields {
-			vMap[f.Name] = v[i]
-		}
-		out = append(out, vMap)
-	}
-
-	return out, nil
+	return t.source.RunSQL(ctx, newStatement, newParams)
 }
 
 func (t Tool) ParseParams(data map[string]any, claims map[string]map[string]any) (tools.ParamValues, error) {