Skip to content

pl-string-input element

Fill in the blank field that allows for string value input.

Sample element

Screenshot of the pl-string-input element

question.html
<pl-string-input answers-name="string_value" label="Prairie"></pl-string-input>
server.py
def generate(data):

    # Answer to fill in the blank input
    data["correct_answers"]["string_value"] = "Learn"

Customizations

Attribute Type Default Description
allow-blank boolean false Whether an empty input box is allowed. By default, empty input boxes will not be graded (invalid format).
answers-name string — Variable name to store data in. Note that this attribute has to be unique within a question, i.e., no value for this attribute should be repeated within a question.
aria-label string — An accessible label for the input.
correct-answer string See description Correct answer for grading. Defaults to data["correct_answers"][answers-name].
correct-answer-format "exact" or "regex" "exact" Whether correct-answer is compared as a literal string ("exact") or interpreted as a regular expression ("regex"). See Matching with regular expressions.
display "block" or "inline" "inline" How to display the input field. Default is "block" if multiline is enabled. Cannot be set to "inline" when multiline="true".
ignore-case boolean false Whether to ignore letter case when grading the answer (e.g. hello matches HELLO).
initial-value string — Initial value is added to the text box the first time it is rendered.
label string — A prefix to display before the input box (e.g., label="$x =$").
multiline boolean false Whether to allow for multiline input using a textarea display.
normalize-to-ascii boolean false Whether non-English characters (accents, non-latin alphabets, fancy quotes) should be normalized to equivalent English characters before submitting the file for grading.
placeholder string — Hint displayed inside the input box describing the expected type of input.
remove-leading-trailing boolean See description Whether to remove leading and trailing blank spaces from the input string. Defaults to true if multiline is enabled, otherwise false.
remove-spaces boolean false Whether to remove blank spaces from the input string.
show-help-text boolean true Show the question mark at the end of the input displaying required input parameters.
show-score boolean true Whether to show the score badge next to this element.
size integer 35 Width of the input box.
suffix string — A suffix to display after the input box (e.g., suffix="items").
weight integer 1 Weight to use when computing a weighted average score over elements.

Migrating from deprecated attributes

The following deprecated attribute is still supported for backward compatibility:

Old syntax New syntax
escape-unicode="<value>" Omit the attribute

The escape-unicode attribute is ignored. Unicode escaping is always applied when needed for displayed submitted and correct answers.

Matching with regular expressions

By default, a submitted answer is graded by comparing it to correct-answer as a literal string. Setting correct-answer-format="regex" instead interprets correct-answer as a Python regular expression, which is useful when several different responses should all be accepted as correct.

The pattern must match the whole submission, not just part of it: grading uses Python's re.fullmatch(), which is equivalent to surrounding the pattern with ^( and )$. To match a substring, include .* in the pattern. Setting ignore-case="true" makes the match case-insensitive.

For example, this question accepts N or nitrogen in any combination of upper- and lowercase, and rejects anything else:

question.html
<pl-string-input
  answers-name="element"
  correct-answer="N|nitrogen"
  correct-answer-format="regex"
  ignore-case="true"
></pl-string-input>

Inline flags at the start of the pattern control matching behavior, such as (?s) so that . also matches newlines, or (?x) to ignore whitespace in the pattern and allow # comments. No Python re flags other than re.IGNORECASE (set by ignore-case) are available.

In the answer panel, the correct answer is shown as the regular expression it matches against. When ignore-case is set, the pattern is displayed with a leading (?i) flag so the case-insensitive matching is visible. Because a pattern is not always a friendly answer to show students, you can add a pl-answer-panel element with a more readable description.

If correct-answer is not a valid regular expression, the question fails to generate and reports an error to the question author.

Using multiline inputs

Note that, in multiline inputs, it can be hard to distinguish between inputs with or without a terminating line break (i.e., an additional "Enter" at the end of the input). Because of that, you are strongly encouraged to leave the default setting of remove-leading-trailing="true" unchanged when using multiline inputs.

Additionally, multiline inputs will have any CR LF ("\r\n" in Python) line breaks normalized to a single LF (a single "\n" in Python). Note that this is different from the behavior of a standard textarea HTML element.

Example implementations

See also