data will be read in post request by defaultsys stdin is used headers and outerboundary are used internally and should not be given environ is dictionary from which cgi environment variables are read keep_blank_values is boolean flag that controls whether blank values are retained or not by defaultit is false strict_parsing is boolean flag that causes an exception to be raised if there is any kind of parsing problem by defaultit is false fieldstorage instance form works similarly to dictionary for examplef form[keywill extract an entry for given parameter key an instance extracted in this manner is either another instance of fieldstorage or an instance of minifieldstorage the following attributes are defined on fattribute description name filename value file type type_options the field nameif specified client-side filename used in uploads value as string file-like object from which data can be read content type dictionary of options specified on the content-type line of the http request the 'content-dispositionfieldnone if not specified dictionary of disposition options dictionary-like object containing all the http header contents disposition disposition_options headers values from form can be extracted using the following methodsform getvalue(fieldname [default]returns the value of given field with the name fieldname if field is defined twicethis function will return list of all values defined if default is suppliedit specifies the value to return if the field is not present one caution with this method is that if the same form field name is included twice in the requestthe returned value will be list containing both values to simplify programmingyou can use form getfirst()which simply returns the first value found form getfirst(fieldname [default]returns the first value defined for field with the name fieldname if default is suppliedit specifies the value to return if the field is not present form getlist(fieldnamereturns list of all values defined for fieldname it always returns listeven if only one value is definedand returns an empty list if no values exist in additionthe cgi module defines classminifieldstoragethat contains only the attribute' name and value this class is used to represent individual fields of form passed in the query stringwhereas fieldstorage is used to contain multiple fields and multipart data lib fl ff