makes MARC record field configurable (#1813)

config/vufind/config.ini

@@ -1719,6 +1719,15 @@ jump_to_single_search_result = false
 ; punctuation, but this can be used when ISBD punctuation is absent (e.g. ", ").
 ;marcPublicationInfoSeparator = " "
 
+; If you have a custom index, you might want to change the field where the full
+; MARC record is supposed to be. The field will be checked and ignored, if it is
+; not a valid index field or does not exist in the record or index schema.
+; If you have multiple fields with MARC content, you may add all of them
+; by using a comma sepated list. The first field is the preferred one, if it does not
+; exist, the next ones are taken.
+; (Default = "fullrecord")
+preferredMarcFields = "fullrecord"
+
 ; When displaying publication information from 260/264, this can be set to true
 ; to make 264 information completely replace 260 information. Default is false,
 ; which will display information from 260 AND 264 when both fields are populated.

module/VuFind/src/VuFind/RecordDriver/MarcReaderTrait.php

@@ -58,7 +58,19 @@ trait MarcReaderTrait
     public function getMarcRecord()
     {
         if (null === $this->lazyMarcRecord) {
-            $marc = trim($this->fields['fullrecord']);
+            // Get preferred MARC field from config, if it is set and is existing
+            $preferredMarcFields = $this->mainConfig->Record->preferredMarcFields
+                ?? 'fullrecord';
+            $preferredMarcFieldArray = explode(',', $preferredMarcFields);
+            $preferredMarcField = 'fullrecord';
+            foreach ($preferredMarcFieldArray as $testField) {
+                if (array_key_exists($testField, $this->fields)) {
+                    $preferredMarcField = $testField;
+                    break;
+                }
+            }
+
+            $marc = trim($this->fields[$preferredMarcField]);
 
             // check if we are dealing with MARCXML
             if (substr($marc, 0, 1) == '<') {