form.setFieldsValue render not true in onChange event

Question

I have a problem when setFieldsValue. This is my code:

<Form.Item>
    {
       form.getFieldDecorator('value_of_type', {
            initialValue: 3
       })(
            <InputNumber
               type='number'
               onChange={value => this.truncateInputNumber(value)}
            />)
     }
</Form.Item>

truncateInputNumber function:

truncateInputNumber = (value) => {
        const {form} = this.props;
        const newValue = Math.floor(value*Math.pow(10,3))/(Math.pow(10,3));
        form.setFieldsValue({
            value_of_type: newValue
        });
        console.log(form.getFieldValue("value_of_type"));
        return newValue
    }

When i type "12,34567" to Input, console.log form.getFieldValue("value_of_type") in truncateInputNumber function, result is true (12,345) but in render, result is false (12,34567).

I don't know why in render function form.getFieldValue("value_of_type") return false result.