validate()¶

The validate() method can be used to mark a package binary as “invalid”, or not working for the current configuration. For example, if we have a header-only library that doesn’t work in Windows, we could have the following conanfile.py:

from conan import ConanFile
from conan.errors import ConanInvalidConfiguration

class Pkg(ConanFile):
    name = "pkg"
    version = "1.0"
    package_type = "header-library"
    settings = "os"

    def validate(self):
        if self.settings.os == "Windows":
            raise ConanInvalidConfiguration("Windows not supported")

    def package_id(self):
        self.info.clear()  # header-only

If we try to create this package in Windows, it will fail, but if we do it in Linux, it will succeed:

$ conan create . -s os=Windows # FAILS
...
ERROR: There are invalid packages:
pkg/1.0: Invalid: Windows not supported
$ conan create . -s os=Linux # WORKS

And if we try to use it in Windows, it will fail again:

$ conan install --requires=pkg/1.0 -s os=Windows # FAILS
...
ERROR: There are invalid packages:
pkg/1.0: Invalid: Windows not supported

When the ConanInvalidConfiguration causes an error, Conan application exit code will be 6

It is possible to check the validity of a given graph without raising errors with the conan graph info command:

$ conan graph info --requires=pkg/1.0 -s os=Windows --filter=binary
conanfile:
ref: conanfile
binary: None
pkg/1.0#cfc18fcc7a50ead278a7c1820be74e56:
ref: pkg/1.0#cfc18fcc7a50ead278a7c1820be74e56
binary: Invalid

The validate() method is evaluated after the whole graph has been computed. This means that it can use the self.dependencies information to raise errors:

from conan import ConanFile
from conan.errors import ConanInvalidConfiguration

class Pkg(ConanFile):
    requires = "dep/0.1"

    def validate(self):
        if self.dependencies["dep"].options.myoption == 2:
            raise ConanInvalidConfiguration("Option 2 of 'dep' not supported")

Note

Best practices

The configure() method evaluates before the graph is complete, so it doesn’t have the real values of the dependencies options. The validate() method is the one that should be checking those dependencies options values if necessary, not configure().