rblib/modles: add from_row() methods to Build and Package

to be able to instantiate those objects providing some rows coming from
the db.
Useful for those cases where the database has to be queried anyway to
gather the list of packages, at that point one might as well gather all
the required data already.

Signed-off-by: Mattia Rizzolo <mattia@debian.org>

bin/rblib/models.py

@@ -139,6 +139,18 @@ class Build:
     def __bool__(self):
         return bool(self.status)
 
+    @classmethod
+    def from_row(cls, row):
+        """
+        Instantiate a Build object already populed.  The row needs to be:
+        (pkgname, suite, arch, status, version, build_date)
+        """
+        build = cls(row[0], row[1], row[2])
+        build._l_status = row[3]
+        build._l_version = row[4]
+        build._l_build_date = str(row[5]) + ' UTC'
+        return build
+
     @lazyproperty
     def status(self):
         self._get_package_status()
@@ -224,12 +236,35 @@ class _Package_cache:
             self._cache[pkgname] = {}
             return self._cache[pkgname]
 
+    def contains(self, pkgname):
+        return pkgname in self._cache
+
 
 class Package:
     def __init__(self, name, no_notes=False):
         self.__dict__ = _Package_cache().get(name)
         self.name = name
 
+    @classmethod
+    def from_row(cls, name, rows):
+        """
+        Instantiate a Build object already populed.  `rows` is an iterable of
+        tuples that need to be:
+        (suite, arch, status, version, build_date)
+        It's not possible to instantiate a new object if there is one already
+        cached for the same package, this method will return that one instead.
+        Further builds cannot be added later and will cause KeyError.
+        """
+        if _Package_cache.contains(name):
+            pkg = cls(name)  # will pick up the cached object
+        else:
+            pkg = cls(name)
+            pkg._l_builds = {s: {} for s in SUITES}
+            for r in rows:
+                b = Build.from_row((pkg, *r))
+                pkg._l_builds[b.suite][b.arch] = b
+        return pkg
+
     @lazyproperty
     def builds(self):
         self._l_builds = {}