chore: Add empty policyMap when policies are empty or null to fix NPE

app/server/appsmith-server/src/main/java/com/appsmith/server/migrations/db/ce/Migration062AddEmptyPolicyMapForNullValues.java

@@ -0,0 +1,100 @@
+package com.appsmith.server.migrations.db.ce;
+
+import com.appsmith.external.helpers.Stopwatch;
+import com.mongodb.client.result.UpdateResult;
+import io.mongock.api.annotations.ChangeUnit;
+import io.mongock.api.annotations.Execution;
+import io.mongock.api.annotations.RollbackExecution;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.mongodb.core.ReactiveMongoTemplate;
+import org.springframework.data.mongodb.core.query.Criteria;
+import org.springframework.data.mongodb.core.query.Query;
+import org.springframework.data.mongodb.core.query.Update;
+import org.springframework.data.mongodb.core.query.UpdateDefinition;
+import reactor.core.publisher.Mono;
+
+import java.util.HashMap;
+import java.util.Set;
+
+import static com.appsmith.server.migrations.constants.FieldName.POLICY_MAP;
+import static org.springframework.data.mongodb.core.query.Criteria.where;
+
+@RequiredArgsConstructor
+@Slf4j
+@ChangeUnit(order = "062", id = "add_empty_policyMap_for_null_entries")
+public class Migration062AddEmptyPolicyMapForNullValues {
+
+    private final ReactiveMongoTemplate mongoTemplate;
+
+    private static final Set<String> CE_COLLECTION_NAMES = Set.of(
+            "actionCollection",
+            "application",
+            "applicationSnapshot",
+            "asset",
+            "collection",
+            "config",
+            "customJSLib",
+            "datasource",
+            "datasourceStorage",
+            "datasourceStorageStructure",
+            "emailVerificationToken",
+            "gitDeployKeys",
+            "newAction",
+            "newPage",
+            "passwordResetToken",
+            "permissionGroup",
+            "plugin",
+            "theme",
+            "user",
+            "userData",
+            "workspace");
+
+    @RollbackExecution
+    public void rollbackExecution() {}
+
+    @Execution
+    public void execute() {
+        Stopwatch stopwatch = new Stopwatch("Migration062AddEmptyPolicyMapForNullValues");
+        Mono.whenDelayError(CE_COLLECTION_NAMES.stream()
+                        .map(c -> addEmptyPolicyMapForNullEntries(mongoTemplate, c))
+                        .toList())
+                .onErrorResume(error -> {
+                    String errorPrefix = "Error while adding empty policyMap for null values";
+                    // As we are using Mono.whenDelayError, we expect multiple errors to be suppressed in a single error
+                    if (error.getSuppressed().length > 0) {
+                        for (Throwable suppressed : error.getSuppressed()) {
+                            log.error(errorPrefix, suppressed);
+                        }
+                    } else {
+                        log.error(errorPrefix, error);
+                    }
+                    return Mono.error(error);
+                })
+                .block();
+        stopwatch.stopAndLogTimeInMillis();
+    }
+
+    public static Mono<Void> addEmptyPolicyMapForNullEntries(
+            ReactiveMongoTemplate mongoTemplate, String collectionName) {
+        log.info("Adding empty policyMap for empty policies {}", collectionName);
+
+        // Update policyMap for documents where policies is empty or null
+        Criteria policyMapNotExists =
+                new Criteria().orOperator(where(POLICY_MAP).exists(false));
+        Criteria notDeletedCriteria = where("deletedAt").isNull();
+
+        final Query query = new Query().addCriteria(policyMapNotExists).addCriteria(notDeletedCriteria);
+        UpdateDefinition update = new Update().set(POLICY_MAP, new HashMap<>());
+        final Mono<UpdateResult> convertToMap = mongoTemplate.updateMulti(query, update, collectionName);
+
+        return convertToMap
+                .elapsed()
+                .doOnSuccess(it -> log.info(
+                        "Migrated {} documents in {} in {}ms",
+                        it.getT2().getModifiedCount(),
+                        collectionName,
+                        it.getT1()))
+                .then();
+    }
+}