update method for taking special character error

I have a update method that use object datasource on web page that takes update field directly. However, some field may have special characters that database wouldn't take it and throw error. In general submission form, I can use code behind like server.htmlencode("") to solve this problem. However, in update method, there is no code behind because the field contents are taken through object datasource parameters. any suggestion how I can handle this in update method case?
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