fix(funcspec): add support for query param filters

* Introduced AllowQueryParamFilters option in SqlQueryOptions
* Implemented applyQueryParamFilters method to handle field filters

pkg/funcspec/function_api.go

@@ -31,6 +31,7 @@ type SqlQueryOptions struct {
 	NoCount                bool
 	BlankParams            bool
 	AllowFilter            bool
+	AllowQueryParamFilters bool
 }
 
 func NewSqlQueryOptions() SqlQueryOptions {
@@ -38,6 +39,7 @@ func NewSqlQueryOptions() SqlQueryOptions {
 		NoCount:                false,
 		BlankParams:            true,
 		AllowFilter:            true,
+		AllowQueryParamFilters: false,
 	}
 }
 
@@ -138,6 +140,11 @@ func (h *Handler) SqlQueryList(sqlquery string, options SqlQueryOptions) HTTPFun
 		// Merge query string parameters
 		sqlquery = h.mergeQueryParams(r, sqlquery, variables, options.AllowFilter, propQry)
 
+		// Apply p_-prefixed query params as field filters
+		if options.AllowQueryParamFilters {
+			sqlquery = h.applyQueryParamFilters(r, sqlquery)
+		}
+
 		// Merge header parameters
 		sqlquery = h.mergeHeaderParams(r, sqlquery, variables, propQry, &complexAPI)
 
@@ -168,9 +175,16 @@ func (h *Handler) SqlQueryList(sqlquery string, options SqlQueryOptions) HTTPFun
 		// Replace meta variables in SQL
 		sqlquery = h.replaceMetaVariables(sqlquery, r, userCtx, metainfo, variables)
 
-		// Remove unused input variables
-		if options.BlankParams {
+		// Replace variables from provided values, then blank any remaining unused ones
 		for _, kw := range inputvars {
+			varName := kw[1 : len(kw)-1] // strip [ and ]
+			if val, ok := variables[varName]; ok {
+				if strVal := fmt.Sprintf("%v", val); strVal != "" {
+					sqlquery = strings.ReplaceAll(sqlquery, kw, ValidSQL(strVal, "colvalue"))
+					continue
+				}
+			}
+			if options.BlankParams {
 				replacement := getReplacementForBlankParam(sqlquery, kw)
 				sqlquery = strings.ReplaceAll(sqlquery, kw, replacement)
 				logger.Debug("Replaced unused variable %s with: %s", kw, replacement)
@@ -474,6 +488,11 @@ func (h *Handler) SqlQuery(sqlquery string, options SqlQueryOptions) HTTPFuncTyp
 		// Merge query string parameters
 		sqlquery = h.mergeQueryParams(r, sqlquery, variables, false, propQry)
 
+		// Apply p_-prefixed query params as field filters
+		if options.AllowQueryParamFilters {
+			sqlquery = h.applyQueryParamFilters(r, sqlquery)
+		}
+
 		// Merge header parameters
 		sqlquery = h.mergeHeaderParams(r, sqlquery, variables, propQry, &complexAPI)
 		hookCtx.ComplexAPI = complexAPI
@@ -520,9 +539,16 @@ func (h *Handler) SqlQuery(sqlquery string, options SqlQueryOptions) HTTPFuncTyp
 			}
 		}
 
-		// Remove unused input variables
-		if options.BlankParams {
+		// Replace variables from provided values, then blank any remaining unused ones
 		for _, kw := range inputvars {
+			varName := kw[1 : len(kw)-1] // strip [ and ]
+			if val, ok := variables[varName]; ok {
+				if strVal := fmt.Sprintf("%v", val); strVal != "" {
+					sqlquery = strings.ReplaceAll(sqlquery, kw, ValidSQL(strVal, "colvalue"))
+					continue
+				}
+			}
+			if options.BlankParams {
 				replacement := getReplacementForBlankParam(sqlquery, kw)
 				sqlquery = strings.ReplaceAll(sqlquery, kw, replacement)
 				logger.Debug("Replaced unused variable %s with: %s", kw, replacement)
@@ -824,6 +850,43 @@ func (h *Handler) mergeHeaderParams(r *http.Request, sqlquery string, variables
 	return sqlquery
 }
 
+// sqlStripStringLiterals removes the contents of single-quoted string literals from SQL,
+// leaving the structural identifiers (column names, table names) intact.
+// Used to check column presence without matching inside string arguments.
+func sqlStripStringLiterals(sql string) string {
+	re := regexp.MustCompile(`'(?:[^']|'')*'`)
+	return re.ReplaceAllString(sql, "''")
+}
+
+// applyQueryParamFilters applies query parameters as SQL field filters when the param name
+// appears as a structural identifier in the SQL (not inside a string literal).
+// e.g. ?rid_parent=0 → (rid_parent = 0 OR rid_parent IS NULL)
+func (h *Handler) applyQueryParamFilters(r *http.Request, sqlquery string) string {
+	sqlStructure := strings.ToLower(sqlStripStringLiterals(sqlquery))
+	for parmk, parmv := range r.URL.Query() {
+		if len(parmv) == 0 || !strings.Contains(sqlStructure, strings.ToLower(parmk)) {
+			continue
+		}
+		val := parmv[0]
+		dec, err := restheadspec.DecodeParam(val)
+		if err == nil {
+			val = dec
+		}
+		col := ValidSQL(parmk, "colname")
+		switch {
+		case val == "0":
+			sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("(%[1]s = 0 OR %[1]s IS NULL)", col))
+		case val == "":
+			sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("(%[1]s = '' OR %[1]s IS NULL)", col))
+		case IsNumeric(val):
+			sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s = %s", col, ValidSQL(val, "colvalue")))
+		default:
+			sqlquery = sqlQryWhere(sqlquery, fmt.Sprintf("%s = '%s'", col, ValidSQL(val, "colvalue")))
+		}
+	}
+	return sqlquery
+}
+
 // replaceMetaVariables replaces meta variables like [rid_user], [user], etc. in the SQL query
 func (h *Handler) replaceMetaVariables(sqlquery string, r *http.Request, userCtx *security.UserContext, metainfo map[string]interface{}, variables map[string]interface{}) string {
 	if strings.Contains(sqlquery, "[p_meta_default]") {