Writing Extentions for gramps
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Writing Filters

Users can create their own filters and add them to gramps. By adding the filter to the user's private filter directory (~/.gramps/filters), the filter will be automatically recognized the next time that the program is started.

Creating a filter

Each filter is a class derived from the Filter.Filter class. The __init__ task may be overridden, but if so, should call the __init__ function on the Filter.Filter class. The parent class provides the variable self.text, which contains the text string passed as the qualifier. This string provides additional information provided by the user. For example, if the filter is used to match names, the qualifier would be used to provide the name that is being compared against.

All filter classes must define a match function. The function takes one argument (other than self), which is an object of type Person to compare against. The function should return a 1 if the person matches the filter, or a zero if the person does not.

Each filter must be registered, so that gramps knows about it. This is accomplished by calling the Filter.register_filter function. This function takes three arguments - the filter class, a description, and flag that indicates if the qualifier string is needed. The description string appears in the pull down interface within gramps, and helps the user choose the appropriate filter. The qualifier flag tells gramps whether or not the filter needs a qualifier string. If this flag is 0, gramps will disable the entry of a qualifier string.

import Filter
import string

# class definition

class SubString(Filter.Filter):

    def match(self,person):
        name = person.getPrimaryName().getName()
        return string.find(name,self.text) >= 0

Filter.register_filter(SubString,
                       description="Names that contain a substring",
	               qualifier=1)

Figure 1. Sample filter implementation

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