This Lektor plugin implements a new datetime-like type,
gittimestamp, which gets it's default value from git timestamps.
This can be used to implement auto-updating pub_date and last_mod
fields in Lektor datamodels.
The gittimestamp type behaves just like the built-in datetime
type, except that if the field is left blank in contents.lr a
default value will be deduced from git timestamps for the file (or
possibly the file’s filesystem mtime.)
If an explicit value for the field is not found, the git log for the
source file (typically contents.lr) is searched using git log --follow --remove-empty -- <source_filename>, and the author
timestamp of all matching commits are considered. Additionally, if
the source file is dirty with respect to git’s HEAD, or if the file is
not checked into the git tree, the file’s mtime is prepended to that
list of timestamps. That list of timestamps is filtered based on the
ignore_commits and skip_first_commit options (see below); then,
finally, a timestamp is selected from those that remain based on the
setting of the strategy option.
The gittimestamp type supports the following options.
This can be set to a string, which is interpreted as a regular
expression. Any git commits whose commit message matches this pattern
are ignored when computing a default timestamp value for the field.
(The matching is performed using re.search.)
If this boolean option is set, the first commit in the git log for the
source file will be ignored. This is useful for implementing a
last_mod field which has a defined value only if the source file has
actually been modified since the initial commit.
This option determines which timestamp is selected from the git log (and/or the file mtime). This can be set to one of four values:
-
last: If the source file is dirty (with respect to the git HEAD tree), the mtime of the file is used. Otherwise, the timestamp of the last (nominally the most recent) non-ignored git commit is used. This is the default strategy. -
first: The timestamp of the first (nominally the earliest) commit is used. -
latest: The latest timestamp is used. Normally this produces the same result atlast, however due to rebasing, cherry-picking, etc. the git timestamps may not be monotonically increasing, in which case this option causes the greatest (most recent) timestamp remaining after any filtering to be selected. -
earliest: The earliest timestamp is used. Normally this produces the same result atfirst, but if the timestamps in the git log are not monotonic, this will select the minimum of all the timestamps remaining after any filtering.
The following global configuration options are supported.
These values are specified by way of the plugins' configuration file:
configs/git-timestamp.ini under the project site directory.
By default, the --follow option is passed to git log when
computing timestamps. This behavior may be adjusted on a global basis by way of the plugins' configuration file (configs/git-timestamp.ini under the project site directory) via the following settings:
This is a boolean setting that specifies whether the
--follow option should be passed to git log when
querying git for timestamps. This options causes git to attempt to
follow file renames.
Currently, the follow_renames is not supported when Lektor
Alternatives are enabled.
If unspecified, follow_renames defaults to false.
Changed in version 1.0.0b3: The default value for
follow_renameswas changed from true to false.
Note Since we currently run
git logon a per-record basis, when--followis specified, copied files may be detected as “renamed”. This may not be ideal.
Set the similarity index threshold (passed to git log via its
-M option) used when detecting renames. This should be
specified as a (floating point) number between 0 and 100,
inclusive. Setting follow_rename_threshold = 100 will limit
detection to exact renames only. The default value is 50.
Here is a simple example excerpt from a datamodel file:
<...>
[fields.last_mod]
label = Time last modified
type = gittimestamp
On a page using the above datamodel, so long as the last_mod field
is left blank in the contents.lr file, the page modification time
will be deduced from timestamp of the most recent git commit which
affected that contents.lr. (Or if that file is dirty, the value of
last_mod will be taken from the file’s filesystem mtime.)
Here is a more complicated example which demonstrates the use of all the options.
<...>
[fields.pub_date]
label = Time first published
type = gittimestamp
strategy = first
[fields.last_mod]
label = Time last modified
type = gittimestamp
ignore_commits = \[nochange\]
skip_first_commit = true
This will get the default value of the pub_date field from the
timestamp of the first (earliest) git commit for the source file.
The default value for last_mod will, as in the previous example, be taken from the
most recent commit for the file, except that:
- any commits whose commit message include the tag
[nochange]will be ignored - the first commit (the one whose timestamp is used for
pub_date) is ignored
If there has only been one commit of the source file, last_mod will not have
a default value. (It will evaluate to a jinja2 Undefined instance.)
A common use case for timestamps is for sorting records.
E.g. in a blog one generally wants to display posts in reverse
chronological order by post date. This generally won't work using
gittimestamp timestamps with version of Lektor before 3.3.
The gittimestamp type is implemented using a field
descriptor. (This is required in order to defer computation of the
field value until after the record for the page is available.) In
lektor<3.3, field descriptors are supported for most usages, the
one glaring exception being when sorting records.
This was fixed in Lektor PR #789 which was merged to the master branch on February 6, 2021, but didn't make it into a release until Lektor 3.3, released on December 13 2021.
Jeff Dairiki [email protected]
