PHP 8.1 deprecation obtained when using Send HTML e-mail Action in Rules

Can you please export your Rule and post it here so we can try to reproduce the error?

I've created a very simple Rule Component that exhibits the reported characteristic. I uploaded it as a text file but can't see how to reference it (sorry - more learning required) but, as it's small, I'm pasting it here:

{ "rules_html_e_mail_test" : {
    "LABEL" : "HTML e-mail test",
    "PLUGIN" : "action set",
    "OWNER" : "rules",
    "REQUIRES" : [ "rules", "mimemail" ],
    "ACTION SET" : [
      { "mimemail" : {
          "USING" : {
            "key" : "html_email_test",
            "to" : "[site:mail]",
            "subject" : "Send HTML e-mail test",
            "body" : "Testing for preg_match_all() deprecation.",
            "language" : [ "" ]
          },
          "PROVIDE" : { "send_status" : { "send_status" : "Send status" } }
        }
      }
    ]
  }
}

As you can see, it's an Action set with a single "Send HTML e-mail" Action, to send an e-mail to the administrative e-mail address for the site.

When I execute the Component from the Administration » Configuration » Workflow » Rules » Components page with PHP 8.1 set, I get the reported deprecation in the log. With PHP 7.4 set, there is no deprecation. If, via the user interface form, I add some text to the Plain text body field, the 8.1 deprecation is no longer reported.

Thanks. I'll see if I can reproduce the problem. This is clearly due to changes in PHP in PHP 8.1. In short, somewhere some module is trying to do token replacement on a string but that string is set to NULL. In PHP 8.1 variable types are enforced more strictly.

This may or may not be a problem with Mime Mail. Or with Rules, or even with core or the contributed Token module if you're using that.

I'm seeing the same thing with a rules component. I've pasted the relevant part below. When any of the tokens is null, I get the error. In one example I'm looking at, [node:field-funding-duration] is null. In mimemail.rules.inc, it looks as if the body field is just passed through without checking the tokens. Since there are multiple tokens in that field (among others), I can't see an easy fix, short of editing the rule and changing all null tokens to empty before building the body field. Suggestions welcome as to the best way to do that, if mimemail can't be patched.

"DO" : [
  { "mimemail" : {
      "USING" : {
        "key" : "funding_source_update",
        "to" : "[node:field-funding-contact-email]",
        "subject" : "Update request for \u0022[node:title]\u0022 listing",
        "body" : "TITLE: [node:title]\u003Cbr\u003E\u003Cbr\u003E\r\nTYPE: [node:field-funding-type]\u003Cbr\u003E\u003Cbr\u003E\r\nSUMMARY: [node:summary]\u003Cbr\u003E\u003Cbr\u003E\r\nDESCRIPTION: [node:body]\u003Cbr\u003E\u003Cbr\u003E\r\nFUNDER(S):\u003Cbr\u003E\r\n[node:field-funding-organization:0:title]: [node:field-funding-organization:0:url]\u003Cbr\u003E\r\n[node:field-funding-organization:1:title]: [node:field-funding-organization:1:url]\u003Cbr\u003E\r\n[node:field-funding-organization:2:title]: [node:field-funding-organization:2:url]\u003Cbr\u003E\r\n[node:field-funding-organization:3:title]: [node:field-funding-organization:3:url]\u003Cbr\u003E\u003Cbr\u003E\r\nAMOUNT: [node:field-funding-amount]\u003Cbr\u003E\u003Cbr\u003E\r\nDEADLINE: [node:field-funding-deadline]\u003Cbr\u003E\u003Cbr\u003E\r\nQUALIFICATIONS: [node:field-funding-qualifications:value]\u003Cbr\u003E\u003Cbr\u003E\r\nDURATION: [node:field-funding-duration]\u003Cbr\u003E\u003Cbr\u003E\r\nTYPES OF SUPPORT: [node:field-funding-support-types]\u003Cbr\u003E\u003Cbr\u003E\r\nSUBJECTS: [node:field-funding-subjects]\u003Cbr\u003E\u003Cbr\u003E\r\nOTHER SUBJECTS: [node:field-funding-other-subjects]\u003Cbr\u003E\u003Cbr\u003E\r\nGEOGRAPHIC FOCUS OR RESTRICTIONS: [node:field_funding_geographic]\u003Cbr\u003E\u003Cbr\u003E\r\nTIPS: [node:field-funding-tips:value]\u003Cbr\u003E\u003Cbr\u003E\r\nPAST PROJECTS: [node:field-funding-pastprojects:value]\u003Cbr\u003E\u003Cbr\u003E\r\nPAST AWARDEES: [node:field-funding-past-awardees:value]\u003Cbr\u003E\u003Cbr\u003E\r\nAPPLICATION LINK: [node:field-funding-applink:url]\u003Cbr\u003E\u003Cbr\u003E\r\nMORE INFORMATION LINK: [node:field-funding-moreinfo:url]\u003Cbr\u003E\u003Cbr\u003E\r\nCONTACT NAME: [node:field-funding-contact-name]\u003Cbr\u003E\u003Cbr\u003E\r\nCONTACT EMAIL: [node:field-funding-contact-email]\u003Cbr\u003E\u003Cbr\u003E\r\nCONTACT PHONE: [node:field-funding-contact-phone]\u003C\/p\u003E\r\n\u003Cp\u003E(Please leave this link intact in your reply: [node:url])\u003C\/p\u003E",
        "language" : [ "" ]
      },
      "PROVIDE" : { "send_status" : { "send_status" : "Send status" } }
    }
  }
]

In PHP 8.1, many modules that implement token replacement have a problem with tokens that default to NULL instead of defaulting to a value with the proper data type (like an empty string or an empty array instead of NULL). With your [node:field-funding-duration], usually what needs to be done is to ensure all your fields have default values and that the code providing the tokens doesn't use NULL values.

I haven't looked much into the original issue yet - the instructions to reproduce in #3 are good, but D7 is very low on my priority list.

The source of the issue for me appears to be line 205 in mimemail.module. My knowledge of PHP and Dupal module constructs is minimal but the following change removed the deprecation I was seeing:

- 205  $message['params']['plaintext'] = token_replace($params['plaintext'], $context, $options);
+ 205  $message['params']['plaintext'] = !empty($params['plaintext']) ? token_replace($params['plaintext'], $context, $options) : ($params['plaintext']);

I'm not going to be so bold as to suggest that this is an appropriate fix for the issue, but it does seem to confirm this line as it's source.

It's also clear that line 204, which performs the same token replacement on the Body field will, if no Body text is entered, give rise to the same deprecation as seen with an empty Plain text body field. (In my test Rule above, I cleared the Body field and entered the text instead in the Plain text body field to prove this.) A similar change to that made in line 205 once again removed the deprecation.

I'm presuming that token replacement on the To and Subject fields (lines 202 and 203 respectively) will not not give rise to the deprecation as these fields are designated on the form as Required fields and hence will never be empty?
But what about lines 51 and 57 in mimemail_action.module? Are they a concern?

A limited contribution I'm afraid, but hopefully it might help move things along.

What if there are multiple tokens in the field? In my case the body field is not empty but some of the tokens within it can be empty (or null, rather). I was thinking I'd have to go through the tokens one at a time and changes the nulls to empties.

I had the same issue and I ended up just setting a value to the plaintext parameter.

I agree the module should handle that better though, either validating the rule to make sure the value is not empty or as #7 suggested, add a check on the value.

This simple patch fixes this issue.