Queries and Subjects¶
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class
dnf.query.
Query
¶ Facilitates lookup of packages in a
Sack
based on given criteria. Query actually does not consult the information in theSack
until it is evaluated. The evaluation happens either explicitly usingrun()
or by iterating the query, for example:#!/usr/bin/python3 import dnf base = dnf.Base() base.fill_sack() q = base.sack.query() i = q.installed() i = i.filter(name='dnf') packages = list(i) # i only gets evaluated here print("Installed dnf package:") for pkg in packages: print(pkg, pkg.reponame)
or:
#!/usr/bin/python3 import dnf base = dnf.Base() base.read_all_repos() base.fill_sack() q = base.sack.query() a = q.available() a = a.filter(name='dnf') print("Available dnf packages:") for pkg in a: # a only gets evaluated here print('{} in repo {}'.format(pkg, pkg.reponame))
Notice that none of the filtering methods mutates the state of the
Query
but produces a new object instead.-
available
()¶ Returns a new query limiting the original query to the packages available from the repositories.
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difference
(other)¶ Returns a new query that contains only those results of original query that are not in the results of the
other
query.
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downgrades
()¶ Returns a new query that limits the result only to packages that can be downgrade candidates to other packages in the current set. Downgrade candidate has the same name, lower EVR and the architecture of the original and the downgrade candidate are suitable for a downgrade. Specifically, the filtering does not take any steps to establish that the downgrade candidate can actually be installed.
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duplicated
()¶ Returns a new query that limits the result only to installed packages of same name and different version. Optional argument exclude accepts a list of package names that will be excluded from result.
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extras
()¶ Returns a new query that limits the result to installed packages that are not present in any repo
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filter
(**kwargs)¶ Returns a new query limiting the original query to the key/value pairs from kwargs. Multiple kwargs can be passed, the filter then works by applying all of them together (logical AND). Values inside of list or query are cumulative (logical OR).
Allowed keys are:
key value type value meaning arch string match against packages’ architecture downgrades boolean see downgrades()
. Defaults toFalse
.empty boolean True
limits to empty result set. Defaults toFalse
.epoch integer match against packages’ epoch. file string match against packages’ files latest integer limit to all packages of number of versions latest_per_arch integer see latest()
.name string match against packages’ names release string match against packages’ releases reponame string match against packages repositories’ names version string match against packages’ versions pkg Query match against packages in query pkg* list match against hawkey.Packages in list provides string match against packages’ provides provides* Hawkey.Reldep match against packages’ provides <DEP> string match against packages’ <DEP> <DEP>* Hawkey.Reldep match a reldep against packages’ <DEP> <DEP>* Query match the result of a query against packages’ <DEP> <DEP>* list(Package) match the list of hawkey.Packages against packages’ <DEP> sourcerpm string match against packages’ source rpm upgrades boolean see upgrades()
. Defaults toFalse
.<DEP>
can be any of: requires, conflicts, obsoletes, enhances, recomments, suggests, supplements* The key can also accept a list of values with specified type.
The key name can be supplemented with a relation-specifying suffix, separated by
__
:key suffix value type semantics eq any exact match; This is the default if no suffix is specified. glob string shell-style wildcard match gt integer the actual value is greater than specified gte integer the actual value is greater than or equal to specified lt integer the actual value is less than specified lte integer the actual value is less than or equal to specified neq any does not equal substr string the specified value is contained in the actual value eqg string exact match or the first higher, used with advisory filters upgrade string skips advisory resolved by installed packages For example, the following creates a query that matches all packages containing the string “club” in its name:
q = base.sack.query().filter(name__substr="club")
Note that using packages or queries for dependency filtering performs a more advanced resolution than using a string or a reldep. When a package list or a query is used, rich dependencies are resolved in a more precise way than what is possible when a string or a reldep is used.
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filterm
(**kwargs)¶ Similar to
dnf.query.Query.filter()
but it modifies the query in place.
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installed
()¶ Returns a new query that limits the result to the installed packages only.
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intersection
(other)¶ Returns a new query where the result contains only packages that are found in both original and
other
queries.
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latest
(limit=1)¶ Returns a new query that limits the result to
limit
highest version of packages per package name and per architecture. In case the limit is negative number, it excludes the number of latest versions according to limit.
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run
()¶ Evaluate the query. Returns a list of matching
dnf.package.Package
instances.
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union
(other)¶ Returns a new query where the results of the
other
query are added to the results of the original query.
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upgrades
()¶ Returns a new query that limits the result only to packages that can be upgrade candidates to at least one package in the current set. Upgrade candidate has the same name, higher EVR and the architectures of the original and the upgrade candidate package are suitable for an upgrade. Specifically, the filtering does not take any steps to establish that the upgrade candidate can actually be installed.
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class
dnf.subject.
Subject
¶ As explained on the DNF man page, users of the CLI are able to select packages for an operation in different formats, leaving seemingly arbitrary parts out of the spec and even using globbing characters. This class implements a common approach to parsing such input and produce a
Query
listing all packages matching the input or aSelector
selecting a single package that best matches the input given a transaction operation.-
__init__
(pkg_spec, ignore_case=False)¶ Initialize the
Subject
with pkg_spec input string with following semantic. If ignore_case isTrue
ignore the case of characters in pkg_spec.
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get_best_query
(sack, with_nevra=True, with_provides=True, with_filenames=True, forms=None)¶ Returns a
Query
yielding packages matching the given input. The result of the returned query can be an empty set if no package matches. sack is theSack
that the returned query will search. with_nevra enable search by nevra, with_provides indicates whether besides package names also packages’ provides are searched for a match, and with_filenames indicates whether besides package provides also packages’ file provides are searched for a match. forms is a list of pattern forms from `hawkey`_. Leaving the parameter toNone
results in using a reasonable default list of forms.
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get_best_selector
(sack, forms=None, obsoletes=True, reponame=None)¶ Returns a
Selector
that will select a single best-matching package when used in a transaction operation. sack and forms have the same meaning as inget_best_query()
. Ifobsoletes
, selector will also contain packages that obsoletes requested packages (default is True). Ifreponame
, the selection of available packages is limited to packages from that repo (default is None).
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get_nevra_possibilities
(self, forms=None)¶ Returns generator for every possible nevra. Each possible nevra is represented by NEVRA class (libdnf) that has attributes name, epoch, version, release, arch. forms have the same meaning as in
get_best_query()
.Example how to use it when it is known that string could be full NEVRA or NEVR:
#!/usr/bin/python3 import dnf import hawkey nevra_string = "dnf-0:4.2.2-2.fc30.noarch" subject = dnf.subject.Subject(nevra_string) possible_nevra = subject.get_nevra_possibilities( forms=[hawkey.FORM_NEVRA, hawkey.FORM_NEVR]) for i,nevra in enumerate(possible_nevra): print("Possibility {} for \"{}\":".format(i+1, nevra_string)) print("name: {}".format(nevra.name)) print("epoch: {}".format(nevra.epoch)) print("version: {}".format(nevra.version)) print("release: {}".format(nevra.release)) print("architecture: {}".format(nevra.arch)) print()
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