- Added MCP validate.

Author: general-kroll-4-life

docs/mcp.md

@@ -44,6 +44,8 @@ Then, assuming you have a `stackql` MCP server serving streamable HTTP on port `
 
 ./build/stackql_mcp_client exec --client-type=http  --url=http://127.0.0.1:9992 --exec.action      list_methods --exec.args '{"provider": "google", "service": "compute", "resource": "networks"}'
 
+./build/stackql_mcp_client exec --client-type=http  --url=http://127.0.0.1:9992 --exec.action validate_query_json_v2      --exec.args '{"sql": "select name from google.compute.networks where project = '"'"'stackql-demo'"'"';"}'
+
 ./build/stackql_mcp_client exec --client-type=http  --url=http://127.0.0.1:9992 --exec.action query_json_v2      --exec.args '{"sql": "select name from google.compute.networks where project = '"'"'stackql-demo'"'"';"}'
 
 ```

internal/stackql/mcpbackend/mcp_reverse_proxy_backend_service.go

@@ -84,8 +84,13 @@ func (b *stackqlMCPReverseProxyService) ExecQuery(ctx context.Context, query str
 	return b.execQuery(ctx, query)
 }
 
-func (b *stackqlMCPReverseProxyService) ValidateQuery(ctx context.Context, query string) (map[string]any, error) {
-	return map[string]any{}, nil
+func (b *stackqlMCPReverseProxyService) ValidateQuery(ctx context.Context, query string) ([]map[string]any, error) {
+	explainQuery := fmt.Sprintf("EXPLAIN %s", query)
+	rows, err := b.query(ctx, explainQuery, unlimitedRowLimit)
+	if err != nil {
+		return nil, err
+	}
+	return rows, nil
 }
 
 func (b *stackqlMCPReverseProxyService) execQuery(ctx context.Context, query string) (map[string]any, error) {

internal/stackql/mcpbackend/mcp_service_stackql.go

@@ -324,8 +324,13 @@ func (b *stackqlMCPService) ExecQuery(ctx context.Context, query string) (map[st
 	return b.execQuery(ctx, query)
 }
 
-func (b *stackqlMCPService) ValidateQuery(ctx context.Context, query string) (map[string]any, error) {
-	return map[string]any{}, nil
+func (b *stackqlMCPService) ValidateQuery(ctx context.Context, query string) ([]map[string]any, error) {
+	explainQuery := fmt.Sprintf("EXPLAIN %s", query)
+	rows, err := b.runPreprocessedQueryJSON(ctx, explainQuery, unlimitedRowLimit)
+	if err != nil {
+		return nil, err
+	}
+	return rows, nil
 }
 
 func (b *stackqlMCPService) execQuery(ctx context.Context, query string) (map[string]any, error) {

internal/stackql/primitivebuilder/explain.go

@@ -54,11 +54,12 @@ func (nb *ExplainBuilder) Build() error {
 			}
 			oneLinerOutput := time.Now().Format("2006-01-02T15:04:05-07:00 MST")
 			resultMap := map[string]any{
-				"query":     nb.handlerCtx.GetRawQuery(),
+				"query":     nb.handlerCtx.GetQuery(),
 				"timestamp": oneLinerOutput,
+				"result":    "OK",
 				"valid":     true,
 			}
-			columns := []string{"query", "timestamp", "valid"}
+			columns := []string{"query", "result", "timestamp", "valid"}
 			return util.PrepareResultSet(
 				internaldto.NewPrepareResultSetPlusRawDTO(
 					nil,

pkg/mcp_server/backend.go

@@ -29,7 +29,7 @@ type Backend interface {
 	ExecQuery(ctx context.Context, query string) (map[string]any, error)
 
 	// Execute a SQL query that does not return rows
-	ValidateQuery(ctx context.Context, query string) (map[string]any, error)
+	ValidateQuery(ctx context.Context, query string) ([]map[string]any, error)
 
 	// Execute a SQL query and return JSON rows with typed input (preferred)
 	RunQueryJSON(ctx context.Context, input dto.QueryJSONInput) ([]map[string]interface{}, error)

pkg/mcp_server/example_backend.go

@@ -52,8 +52,8 @@ func (b *ExampleBackend) RunQueryJSON(ctx context.Context, input dto.QueryJSONIn
 	return []map[string]interface{}{}, nil
 }
 
-func (b *ExampleBackend) ValidateQuery(ctx context.Context, query string) (map[string]any, error) {
-	return map[string]any{}, nil
+func (b *ExampleBackend) ValidateQuery(ctx context.Context, query string) ([]map[string]any, error) {
+	return []map[string]any{}, nil
 }
 
 // func (b *ExampleBackend) ListTableResources(ctx context.Context, hI dto.HierarchyInput) ([]string, error) {

pkg/mcp_server/server.go

@@ -230,8 +230,7 @@ func newMCPServer(config *Config, backend Backend, logger *logrus.Logger) (MCPSe
 			Description: "Explain a SQL query and return a JSON object expressing success, or else an error.",
 		},
 		func(ctx context.Context, req *mcp.CallToolRequest, args dto.QueryJSONInput) (*mcp.CallToolResult, any, error) {
-			args.SQL = fmt.Sprintf("EXPLAIN %s", args.SQL)
-			arr, err := backend.RunQueryJSON(ctx, args)
+			arr, err := backend.ValidateQuery(ctx, args.SQL)
 			if err != nil {
 				return nil, nil, err
 			}