added install code to create custom field

batchexportperm.php

@@ -85,6 +85,46 @@ function batchexportperm_civicrm_upgrade($op, CRM_Queue_Queue $queue = NULL) {
  */
 function batchexportperm_civicrm_managed(&$entities) {
   _batchexportperm_civix_civicrm_managed($entities);
+  $entities[] = [
+    'module' => 'org.agbu.batchexportperm',
+    'name' => 'batchexportperm_batch_details',
+    'entity' => 'CustomGroup',
+    'params' => [
+      'version' => 3,
+      'name' => 'batchexportperm_batch_details',
+      'title' => 'Batch Details',
+      'extends' => 'Contribution',
+      'style' => 'Inline',
+      'collapse_display' => TRUE,
+      'is_active' => TRUE,
+      'is_multiple' => FALSE,
+      'collapse_adv_display' => FALSE,
+      'is_reserved' => TRUE,
+    ],
+  ];
+  $entities[] = [
+    'module' => 'org.agbu.batchexportperm',
+    'name' => 'export_date',
+    'entity' => 'CustomField',
+    'params' => [
+      'version' => 3,
+      'name' => 'export_date',
+      'label' => 'Export Date',
+      'data_type' => 'Date',
+      'html_type' => 'Select Date',
+      'is_required' => FALSE,
+      'is_searchable' => FALSE,
+      'is_search_range' => FALSE,
+      'is_active' => TRUE,
+      'is_view' => TRUE,
+      'date_format' => 'mm/dd/yy',
+      'text_length' => 255,
+      'column_name' => 'export_date',
+      'note_columns' => 150,
+      'note_rows' => 4,
+      'custom_group_id' => 'batchexportperm_batch_details',
+    ],
+  ];
 }
 
 /**
@@ -226,8 +266,8 @@ function _batchexportperm_civicrm_check_permission($contributionId, $errorType =
 function _batchexportperm_civicrm_allow_contribution_to_edit($contributionId) {
   $customFieldId = civicrm_api3('CustomField', 'getvalue', [
     'return' => "id",
-    'custom_group_id' => "Batch_Details",
-    'name' => "Export_Date",
+    'custom_group_id' => "batchexportperm_batch_details",
+    'name' => "export_date",
   ]);
   $exportDate = civicrm_api3('Contribution', 'getvalue', [
     'return' => "custom_{$customFieldId}",