Help Texts

help text

A short explanation to be displayed as tooltip when the user hovers over a form field, a menu item, or a toolbar button.

Help texts should be (1) helpful to the end user, (2) translated and (3) maintainable. Lino provides several approaches for reaching these goals.

The primitive way

Help texts can be defined and maintained by the application developer by setting the help_text attribute of a field, actor or action. As a developer you should wrap that string into gettext() to have it translatable. Fictive example:

from lino.api import dd, _

class MyModel(dd.Model):
    """MyModel is an important example."""

    universe = models.CharField(_("First field"),
        blank=True, max_length=100, help_text=_("""
The first field contains an optional answer to the
question about life, the universe and everything.
"""))

Having help texts maintained by the end users

Help texts can be customized locally per site by the end users as customized help text. This feature is not being used seriously on any known production site.

Using the help texts extractor

In bigger projects we want to differentiate between application development and authoring of end user documentation. That's why the application developer can delegate help text maintenance to the documentation maintainer.

This is where we use the help texts extractor.

help texts extractor

A Sphinx extension that extracts help texts from your Sphinx documentation to help_texts.py files, which Lino will load at startup.

Writing the help texts

With the help texts extractor you write the help texts in your documentation using prosa style:

.. class:: MyModel

    MyModel is an important example.

    .. attribute:: universe

        The first field contains an optional answer to the
        question about life, the universe and everything.

        This field is a simple char field. Blabla more documentation.

Write help texts so that extractor can find them.

Note that only the first paragraph of the content of every class and attribute directive is taken as help text, and that any formatting and links are removed.

Help texts are stored on the field descriptor object, which in case of MTI children can bring a surprising behaviour. As an example, compare the fields Partner.name and Person.name (in the lino_xl.lib.contacts plugin) The Sphinx docs defines documentation for both fields. Obviously we don't want the help text for the name field on Partner became that of the Person.

Extracting the help texts

When you run inv bd on a Sphinx doctree that has help_texts_extractor installed, Sphinx takes the first paragraph of every object description in your Sphinx documentation and writes it to a help_texts.py file.

Configure the help texts extractor in the conf.py of your doctree by adding lino.sphinxcontrib.help_texts_extractor to your extensions and defining a help_texts_builder_targets setting. For example:

extensions += ['lino.sphinxcontrib.help_texts_extractor']
help_texts_builder_targets = {
    'lino_algus.': 'lino_algus.lib.algus'
}

Translate help texts

After having extracted help texts, the application developer can run inv mm and start translating them.

Loading help texts at startup

Lino will load these help_texts.py files at startup and "inject" them to the fields, actions and actors as if they had been defined by the application source code.

More precisely, when a Lino Site initializes, it looks for a file named help_texts.py in every plugin directory. If such a file exists, Lino imports it and expects it to contain a dict of the form:

from lino.api import _
help_texts = {
    'foo': _("A foo is a bar without baz.")
}

Advantages

  • Better readability, better maintainability.

  • As an application developer you don't need to worry about Python syntax consideration when editing your help text

  • Same source is used for both the docs and the user interface. You don't need to write (and maintain) these texts twice.

Pitfalls

When the database structure changes in the code and you forget to adapt the specs accordingly, your help texts may "disappear" without notice. You can avoid this by making your test suite cover the help texts.

You do this by simply showing the help texts of a model or actor in your functional specifications using the show_fields or show_columns function.

Example:

>>> import lino
>>> lino.startup('lino_book.projects.min2.settings.doctests')
>>> from lino.api.doctest import *
>>> show_fields(contacts.Person)
+---------------+----------------------------+-----------------------------------------------------------------+
| Internal name | Verbose name               | Help text                                                       |
+===============+============================+=================================================================+
| email         | e-mail address             | The primary email address.                                      |
+---------------+----------------------------+-----------------------------------------------------------------+
| language      | Language                   | The language to use when communicating with this partner.       |
+---------------+----------------------------+-----------------------------------------------------------------+
| phone         | Phone                      | The primary phone number.                                       |
+---------------+----------------------------+-----------------------------------------------------------------+
| gsm           | GSM                        | The primary mobile phone number.                                |
+---------------+----------------------------+-----------------------------------------------------------------+
| city          | Locality                   | The locality, i.e. usually a village, city or town.             |
+---------------+----------------------------+-----------------------------------------------------------------+
| addr1         | Address line before street | Address line before street                                      |
+---------------+----------------------------+-----------------------------------------------------------------+
| street_prefix | Street prefix              | Text to print before name of street, but to ignore for sorting. |
+---------------+----------------------------+-----------------------------------------------------------------+
| street        | Street                     | Name of street, without house number.                           |
+---------------+----------------------------+-----------------------------------------------------------------+
| street_no     | No.                        | House number.                                                   |
+---------------+----------------------------+-----------------------------------------------------------------+
| street_box    | Box                        | Text to print after street number on the same line.             |
+---------------+----------------------------+-----------------------------------------------------------------+
| addr2         | Address line after street  | Address line to print below street line.                        |
+---------------+----------------------------+-----------------------------------------------------------------+
| prefix        | Name prefix                | An optional name prefix. For organisations this is inserted     |
|               |                            | before the name, for persons this is inserted between first     |
|               |                            | name and last name.                                             |
+---------------+----------------------------+-----------------------------------------------------------------+
| name          | Name                       | The full name of this partner. Used for alphabetic sorting.     |
+---------------+----------------------------+-----------------------------------------------------------------+
| title         | Title                      | Used to specify a professional position or academic             |
|               |                            | qualification like "Dr." or "PhD".                              |
+---------------+----------------------------+-----------------------------------------------------------------+
| first_name    | First name                 | The first name, also known as given name.                       |
+---------------+----------------------------+-----------------------------------------------------------------+
| middle_name   | Middle name                | A space-separated list of all middle names.                     |
+---------------+----------------------------+-----------------------------------------------------------------+
| last_name     | Last name                  | The last name, also known as family name.                       |
+---------------+----------------------------+-----------------------------------------------------------------+
| gender        | Gender                     | The sex of this person (male or female).                        |
+---------------+----------------------------+-----------------------------------------------------------------+
| birth_date    | Birth date                 | Uncomplete dates are allowed, e.g.                              |
|               |                            | "00.00.1980" means "some day in 1980",                          |
|               |                            | "00.07.1980" means "in July 1980"                               |
|               |                            | or "23.07.0000" means "on a 23th of July".                      |
+---------------+----------------------------+-----------------------------------------------------------------+
| age           | Age                        | Virtual field displaying the age in years.                      |
+---------------+----------------------------+-----------------------------------------------------------------+
| mti_navigator | See as                     | A virtual field which defines buttons for switching between the |
|               |                            | different views.                                                |
+---------------+----------------------------+-----------------------------------------------------------------+
| municipality  | Municipality               | The municipality, i.e. either the city or a parent of it.       |
+---------------+----------------------------+-----------------------------------------------------------------+

Because the above text is now in your specifications, doctest will warn you whenever any of the help tests changes.

When you give an actor as argument to show_fields, it will show the parameter fields of that actor.

>>> show_fields(contacts.Persons)
================ ================ ===============================
 Internal name    Verbose name     Help text
---------------- ---------------- -------------------------------
 observed_event   Observed event   Extended filter criteria
 start_date       Period from      Start date of observed period
 end_date         until            End date of observed period
================ ================ ===============================
>>> show_columns(contacts.Persons)
=============== ================ ============================
 Internal name   Verbose name     Help text
--------------- ---------------- ----------------------------
 email           e-mail address   The primary email address.
=============== ================ ============================
>>> show_columns(contacts.Persons, all=True)
================ ================ ============================
 Internal name    Verbose name     Help text
---------------- ---------------- ----------------------------
 address_column   Address
 email            e-mail address   The primary email address.
 id               ID
================ ================ ============================

A real-world example are the specs of lino_avanti.lib.avanti.AllClients, which include a call to lino.api.doctests.show_columns().

The help_texts.py file

help_texts.py

The help_texts.py file contains object descriptions to be installed as help texts of user interface widgets. The file is automatically generated from the documentation.

The file is generated only by a full build, i.e. when all pages of the doctree were built. If you want to be sure, you must run inv clean before running inv bd. So in practice you will say inv clean -b bd

help_texts_builder_targets

A setting in the conf.py of your doctree. A dictionary mapping beginnings of module names to the full name of the Python package where the help_texts.py is to be written.

See also

Accessing help texts from your code

>>> import lino
>>> lino.startup('lino_book.projects.min2.settings.doctests')
>>> from lino.api.doctest import *

Here is how Lino internally accesses the help text of a database field:

>>> fld = rt.models.contacts.Partner._meta.get_field('name')
>>> print(fld.help_text)  
The full name of this partner. Used for alphabetic sorting.

Above text is the first sentence extracted from the documentation of the lino_xl.lib.contacts.Partner.name field.

The following is not true:

>> fld = rt.models.contacts.Person._meta.get_field('name')
>> print(fld.help_text)  #doctest: +NORMALIZE_WHITESPACE
The full name of this person, used for sorting.

Don't read on

>>> from lino.api import _
>>> from lino.utils.jsgen import py2js
>>> x = dict(tooltip=_("""This is a "foo", IOW a bar."""))
>>> print(py2js(x))
{ "tooltip": "This is a \"foo\", IOW a bar." }