Ensure that a field/lookup combo occurs at most once in queriesList

requirements.txt

@@ -5,7 +5,7 @@ Django==2.2.24			# 2021-06-11
 feedparser==5.2.1		# Check: not updated since 2016
 psycopg2==2.8.6	  		# 2020-09-19 PostgreSQL engine
 pytz==2017.2			# Timezone package
-# djangorestframework==3.9.3	# 2019-12-05  IMPORTANT: update templates/rest_framework/base.html if corresponding file rest_framework/templates/rest_framework/base.html has changed
+# djangorestframework==3.9.3	# DEPREC, see next entry -- 2019-12-05  IMPORTANT: update templates/rest_framework/base.html if corresponding file rest_framework/templates/rest_framework/base.html has changed
 git+git://github.com/SciPost/django-rest-framework.git@bootstrap-v5
 requests==2.25.1		# 2021-05-21
 pyotp==2.2.7

scipost_vue/components/SearchableObjectsTable.vue

@@ -237,7 +237,13 @@ export default {
 	const getAllowedLookups = () => {
 	    if (newQueryField.value) {
 		allowedLookups.value = filteringFieldsAdvanced.value.find(
-		    el => el.field == newQueryField.value).lookups
+		    el => el.field == newQueryField.value
+		).lookups.filter( // remove already-used lookups
+		    item => !queriesList.value.some( el => {
+			return (el.field === newQueryField.value &&
+				el.lookup === item)
+			})
+		)
 		// Set choice to first value by default
 		newQueryLookup.value = allowedLookups.value[0]
 	    }
@@ -324,6 +330,7 @@ export default {
 	watch(basicSearchQuery, getObjects)
 	watch(perPage, () => currentPage.value = 1)
 	watch(newQueryField, getAllowedLookups)
+	watch(queriesList, () => { if (newQueryField.value) getAllowedLookups()}) // to cover binning a query
 	watch(queryParameters, getObjects)
 
 	return {