# Symbol Parameters Objects

Note that these objects are internal and can't be created manually.
They can only be returned with other onetick.py functions or methods, e.g. [`onetick.py.Source.to_symbol_param()`](../source/to_symbol_param.md#onetick.py.Source.to_symbol_param)

### *class* \_SymbolParamSource

Bases: [`object`](https://docs.python.org/3/library/functions.html#object)

Internal container that provides access to symbol parameters.
The object is read-only, you can only get symbol parameters with it.

#### *property* schema

Represents actual python data schema in the column name -> type format.

#### \_\_getitem_\_(key)

Get symbol parameter with corresponding `key`.
Raises an error if such column does not exist.

### *class* \_SymbolParamColumn

Bases: [`Column`](../operation/root.md#onetick.py.Column)

Internal object representing OneTick's symbol parameters.
Can be used in other onetick.py methods to specify if object is symbol parameter.