add field-based find functions

store.go

@@ -646,3 +646,85 @@ func NewSingleton[S any](initFunc func() *S) func() *S {
 		return store
 	}
 }
+
+// ============================================================================
+// Find Functions
+// ============================================================================
+
+// FindByField performs a linear search for items where fieldName equals value
+func (bs *BaseStore[T]) FindByField(fieldName string, value any) []*T {
+	bs.mu.RLock()
+	defer bs.mu.RUnlock()
+
+	var result []*T
+	for _, item := range bs.items {
+		itemValue := reflect.ValueOf(item).Elem()
+		fieldValue := itemValue.FieldByName(fieldName)
+		if !fieldValue.IsValid() {
+			continue
+		}
+
+		if fieldValue.Interface() == value {
+			result = append(result, item)
+		}
+	}
+	return result
+}
+
+// FindFirstByField returns the first item where fieldName equals value
+func (bs *BaseStore[T]) FindFirstByField(fieldName string, value any) (*T, bool) {
+	bs.mu.RLock()
+	defer bs.mu.RUnlock()
+
+	for _, item := range bs.items {
+		itemValue := reflect.ValueOf(item).Elem()
+		fieldValue := itemValue.FieldByName(fieldName)
+		if !fieldValue.IsValid() {
+			continue
+		}
+
+		if fieldValue.Interface() == value {
+			return item, true
+		}
+	}
+	return nil, false
+}
+
+// FindByFields performs a linear search with multiple field conditions (AND logic)
+func (bs *BaseStore[T]) FindByFields(conditions map[string]any) []*T {
+	bs.mu.RLock()
+	defer bs.mu.RUnlock()
+
+	var result []*T
+	for _, item := range bs.items {
+		itemValue := reflect.ValueOf(item).Elem()
+		matches := true
+
+		for fieldName, expectedValue := range conditions {
+			fieldValue := itemValue.FieldByName(fieldName)
+			if !fieldValue.IsValid() || fieldValue.Interface() != expectedValue {
+				matches = false
+				break
+			}
+		}
+
+		if matches {
+			result = append(result, item)
+		}
+	}
+	return result
+}
+
+// FindByPredicate allows custom filtering logic
+func (bs *BaseStore[T]) FindByPredicate(predicate func(*T) bool) []*T {
+	bs.mu.RLock()
+	defer bs.mu.RUnlock()
+
+	var result []*T
+	for _, item := range bs.items {
+		if predicate(item) {
+			result = append(result, item)
+		}
+	}
+	return result
+}