import datetime import os import re import shutil from . import util _sourceless_rev_file = re.compile(r'(.*\.py)(c|o)?$') _only_source_rev_file = re.compile(r'(.*\.py)$') _legacy_rev = re.compile(r'([a-f0-9]+)\.py$') _mod_def_re = re.compile(r'(upgrade|downgrade)_([a-z0-9]+)') _slug_re = re.compile(r'\w+') _default_file_template = "%(rev)s_%(slug)s" _relative_destination = re.compile(r'(?:\+|-)\d+') class ScriptDirectory(object): """Provides operations upon an Alembic script directory. This object is useful to get information as to current revisions, most notably being able to get at the "head" revision, for schemes that want to test if the current revision in the database is the most recent:: from alembic.script import ScriptDirectory from alembic.config import Config config = Config() config.set_main_option("script_location", "myapp:migrations") script = ScriptDirectory.from_config(config) head_revision = script.get_current_head() """ def __init__(self, dir, file_template=_default_file_template, truncate_slug_length=40, sourceless=False): self.dir = dir self.versions = os.path.join(self.dir, 'versions') self.file_template = file_template self.truncate_slug_length = truncate_slug_length or 40 self.sourceless = sourceless if not os.access(dir, os.F_OK): raise util.CommandError("Path doesn't exist: %r. Please use " "the 'init' command to create a new " "scripts folder." % dir) @classmethod def from_config(cls, config): """Produce a new :class:`.ScriptDirectory` given a :class:`.Config` instance. The :class:`.Config` need only have the ``script_location`` key present. """ script_location = config.get_main_option('script_location') if script_location is None: raise util.CommandError("No 'script_location' key " "found in configuration.") truncate_slug_length = config.get_main_option("truncate_slug_length") if truncate_slug_length is not None: truncate_slug_length = int(truncate_slug_length) return ScriptDirectory( util.coerce_resource_to_filename(script_location), file_template=config.get_main_option( 'file_template', _default_file_template), truncate_slug_length=truncate_slug_length, sourceless=config.get_main_option("sourceless") == "true" ) def walk_revisions(self, base="base", head="head"): """Iterate through all revisions. This is actually a breadth-first tree traversal, with leaf nodes being heads. """ if head == "head": heads = set(self.get_heads()) else: heads = set([head]) while heads: todo = set(heads) heads = set() for head in todo: if head in heads: break for sc in self.iterate_revisions(head, base): if sc.is_branch_point and sc.revision not in todo: heads.add(sc.revision) break else: yield sc def get_revision(self, id_): """Return the :class:`.Script` instance with the given rev id.""" id_ = self.as_revision_number(id_) try: return self._revision_map[id_] except KeyError: # do a partial lookup revs = [x for x in self._revision_map if x is not None and x.startswith(id_)] if not revs: raise util.CommandError("No such revision '%s'" % id_) elif len(revs) > 1: raise util.CommandError( "Multiple revisions start " "with '%s', %s..." % ( id_, ", ".join("'%s'" % r for r in revs[0:3]) )) else: return self._revision_map[revs[0]] _get_rev = get_revision def as_revision_number(self, id_): """Convert a symbolic revision, i.e. 'head' or 'base', into an actual revision number.""" if id_ == 'head': id_ = self.get_current_head() elif id_ == 'base': id_ = None return id_ _as_rev_number = as_revision_number def iterate_revisions(self, upper, lower): """Iterate through script revisions, starting at the given upper revision identifier and ending at the lower. The traversal uses strictly the `down_revision` marker inside each migration script, so it is a requirement that upper >= lower, else you'll get nothing back. The iterator yields :class:`.Script` objects. """ if upper is not None and _relative_destination.match(upper): relative = int(upper) revs = list(self._iterate_revisions("head", lower)) revs = revs[-relative:] if len(revs) != abs(relative): raise util.CommandError("Relative revision %s didn't " "produce %d migrations" % (upper, abs(relative))) return iter(revs) elif lower is not None and _relative_destination.match(lower): relative = int(lower) revs = list(self._iterate_revisions(upper, "base")) revs = revs[0:-relative] if len(revs) != abs(relative): raise util.CommandError("Relative revision %s didn't " "produce %d migrations" % (lower, abs(relative))) return iter(revs) else: return self._iterate_revisions(upper, lower) def _iterate_revisions(self, upper, lower): lower = self.get_revision(lower) upper = self.get_revision(upper) orig = lower.revision if lower else 'base', \ upper.revision if upper else 'base' script = upper while script != lower: if script is None and lower is not None: raise util.CommandError( "Revision %s is not an ancestor of %s" % orig) yield script downrev = script.down_revision script = self._revision_map[downrev] def _upgrade_revs(self, destination, current_rev): revs = self.iterate_revisions(destination, current_rev) return [ (script.module.upgrade, script.down_revision, script.revision, script.doc) for script in reversed(list(revs)) ] def _downgrade_revs(self, destination, current_rev): revs = self.iterate_revisions(current_rev, destination) return [ (script.module.downgrade, script.revision, script.down_revision, script.doc) for script in revs ] def run_env(self): """Run the script environment. This basically runs the ``env.py`` script present in the migration environment. It is called exclusively by the command functions in :mod:`alembic.command`. """ util.load_python_file(self.dir, 'env.py') @property def env_py_location(self): return os.path.abspath(os.path.join(self.dir, "env.py")) @util.memoized_property def _revision_map(self): map_ = {} for file_ in os.listdir(self.versions): script = Script._from_filename(self, self.versions, file_) if script is None: continue if script.revision in map_: util.warn("Revision %s is present more than once" % script.revision) map_[script.revision] = script for rev in map_.values(): if rev.down_revision is None: continue if rev.down_revision not in map_: util.warn("Revision %s referenced from %s is not present" % (rev.down_revision, rev)) rev.down_revision = None else: map_[rev.down_revision].add_nextrev(rev.revision) map_[None] = None return map_ def _rev_path(self, rev_id, message, create_date): slug = "_".join(_slug_re.findall(message or "")).lower() if len(slug) > self.truncate_slug_length: slug = slug[:self.truncate_slug_length].rsplit('_', 1)[0] + '_' filename = "%s.py" % ( self.file_template % { 'rev': rev_id, 'slug': slug, 'year': create_date.year, 'month': create_date.month, 'day': create_date.day, 'hour': create_date.hour, 'minute': create_date.minute, 'second': create_date.second } ) return os.path.join(self.versions, filename) def get_current_head(self): """Return the current head revision. If the script directory has multiple heads due to branching, an error is raised. Returns a string revision number. """ current_heads = self.get_heads() if len(current_heads) > 1: raise util.CommandError('Only a single head is supported. The ' 'script directory has multiple heads (due to branching), which ' 'must be resolved by manually editing the revision files to ' 'form a linear sequence. Run `alembic branches` to see the ' 'divergence(s).') if current_heads: return current_heads[0] else: return None _current_head = get_current_head """the 0.2 name, for backwards compat.""" def get_heads(self): """Return all "head" revisions as strings. Returns a list of string revision numbers. This is normally a list of length one, unless branches are present. The :meth:`.ScriptDirectory.get_current_head()` method can be used normally when a script directory has only one head. """ heads = [] for script in self._revision_map.values(): if script and script.is_head: heads.append(script.revision) return heads def get_base(self): """Return the "base" revision as a string. This is the revision number of the script that has a ``down_revision`` of None. Behavior is not defined if more than one script has a ``down_revision`` of None. """ for script in self._revision_map.values(): if script and script.down_revision is None \ and script.revision in self._revision_map: return script.revision else: return None def _generate_template(self, src, dest, **kw): util.status("Generating %s" % os.path.abspath(dest), util.template_to_file, src, dest, **kw ) def _copy_file(self, src, dest): util.status("Generating %s" % os.path.abspath(dest), shutil.copy, src, dest) def generate_revision(self, revid, message, refresh=False, **kw): """Generate a new revision file. This runs the ``script.py.mako`` template, given template arguments, and creates a new file. :param revid: String revision id. Typically this comes from ``alembic.util.rev_id()``. :param message: the revision message, the one passed by the -m argument to the ``revision`` command. :param refresh: when True, the in-memory state of this :class:`.ScriptDirectory` will be updated with a new :class:`.Script` instance representing the new revision; the :class:`.Script` instance is returned. If False, the file is created but the state of the :class:`.ScriptDirectory` is unmodified; ``None`` is returned. """ current_head = self.get_current_head() create_date = datetime.datetime.now() path = self._rev_path(revid, message, create_date) self._generate_template( os.path.join(self.dir, "script.py.mako"), path, up_revision=str(revid), down_revision=current_head, create_date=create_date, message=message if message is not None else ("empty message"), **kw ) if refresh: script = Script._from_path(self, path) self._revision_map[script.revision] = script if script.down_revision: self._revision_map[script.down_revision].\ add_nextrev(script.revision) return script else: return None class Script(object): """Represent a single revision file in a ``versions/`` directory. The :class:`.Script` instance is returned by methods such as :meth:`.ScriptDirectory.iterate_revisions`. """ nextrev = frozenset() def __init__(self, module, rev_id, path): self.module = module self.revision = rev_id self.path = path self.down_revision = getattr(module, 'down_revision', None) revision = None """The string revision number for this :class:`.Script` instance.""" module = None """The Python module representing the actual script itself.""" path = None """Filesystem path of the script.""" down_revision = None """The ``down_revision`` identifier within the migration script.""" @property def doc(self): """Return the docstring given in the script.""" return re.split("\n\n", self.longdoc)[0] @property def longdoc(self): """Return the docstring given in the script.""" doc = self.module.__doc__ if doc: if hasattr(self.module, "_alembic_source_encoding"): doc = doc.decode(self.module._alembic_source_encoding) return doc.strip() else: return "" def add_nextrev(self, rev): self.nextrev = self.nextrev.union([rev]) @property def is_head(self): """Return True if this :class:`.Script` is a 'head' revision. This is determined based on whether any other :class:`.Script` within the :class:`.ScriptDirectory` refers to this :class:`.Script`. Multiple heads can be present. """ return not bool(self.nextrev) @property def is_branch_point(self): """Return True if this :class:`.Script` is a branch point. A branchpoint is defined as a :class:`.Script` which is referred to by more than one succeeding :class:`.Script`, that is more than one :class:`.Script` has a `down_revision` identifier pointing here. """ return len(self.nextrev) > 1 @property def log_entry(self): return \ "Rev: %s%s%s\n" \ "Parent: %s\n" \ "Path: %s\n" \ "\n%s\n" % ( self.revision, " (head)" if self.is_head else "", " (branchpoint)" if self.is_branch_point else "", self.down_revision, self.path, "\n".join( " %s" % para for para in self.longdoc.splitlines() ) ) def __str__(self): return "%s -> %s%s%s, %s" % ( self.down_revision, self.revision, " (head)" if self.is_head else "", " (branchpoint)" if self.is_branch_point else "", self.doc) @classmethod def _from_path(cls, scriptdir, path): dir_, filename = os.path.split(path) return cls._from_filename(scriptdir, dir_, filename) @classmethod def _from_filename(cls, scriptdir, dir_, filename): if scriptdir.sourceless: py_match = _sourceless_rev_file.match(filename) else: py_match = _only_source_rev_file.match(filename) if not py_match: return None py_filename = py_match.group(1) if scriptdir.sourceless: is_c = py_match.group(2) == 'c' is_o = py_match.group(2) == 'o' else: is_c = is_o = False if is_o or is_c: py_exists = os.path.exists(os.path.join(dir_, py_filename)) pyc_exists = os.path.exists(os.path.join(dir_, py_filename + "c")) # prefer .py over .pyc because we'd like to get the # source encoding; prefer .pyc over .pyo because we'd like to # have the docstrings which a -OO file would not have if py_exists or is_o and pyc_exists: return None module = util.load_python_file(dir_, filename) if not hasattr(module, "revision"): # attempt to get the revision id from the script name, # this for legacy only m = _legacy_rev.match(filename) if not m: raise util.CommandError( "Could not determine revision id from filename %s. " "Be sure the 'revision' variable is " "declared inside the script (please see 'Upgrading " "from Alembic 0.1 to 0.2' in the documentation)." % filename) else: revision = m.group(1) else: revision = module.revision return Script(module, revision, os.path.join(dir_, filename))