task: #3457624: Add a README.md and document using :value tokens to avoid prefix and suffix in expressions

Orkut Murat Yılmazrequested to merge
issue/field_expression-3457624:3457624-prefix-and-suffix into 2.x

Closes #3457624

Adds a README.md to the module, following the drupal.org README.md template. The module had no README, and the :value token needed to calculate with prefixed or suffixed fields was not documented anywhere.

What the README covers

  • Requirements (Token, webit/eval-math), recommended modules (Devel), installation and configuration.
  • Field types, field settings and the "Always Evaluate Expression?" display setting, plus a note on the legacy Expression field type.
  • Expression syntax: operators, built-in functions, ; separated statements, user-defined functions.
  • Tokens and token default values.
  • "Use raw values in tokens": field tokens such as [node:field_price] return the formatted value (prefix, suffix, thousand separator), which evaluates to 0; [node:field_price:value] returns the stored number.
  • Troubleshooting for a field that is always 0, and for values that do not follow changes in referenced entities.

Testing

The token examples were checked on 2.x-dev with Drupal 11 and Token 8.x-1.17, using a decimal field with prefix $ and suffix kg and the value 1234.5:

Expression After token replacement Result
[node:field_price] * 2 $1234.50 kg * 2 0
[node:field_price:value] * 2 1234.5 * 2 2469
[node:field_product:entity:field_price:value] * 2 1234.50 * 2 2469

Notes

  • Documentation only; no code changes.
  • Tamper integration and automatic stripping of non-numeric characters were considered and left out; see the issue summary for the reasoning.

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