add validation folder in database

packages/core/database/lib/index.js

@@ -11,8 +11,7 @@ const errors = require('./errors');
 
 // TODO: move back into strapi
 const { transformContentTypes } = require('./utils/content-types');
-const { getJoinTableName } = require('./metadata/relations');
-const types = require('./types');
+const { validateDatabase } = require('./validations');
 
 class Database {
   constructor(config) {
@@ -74,80 +73,11 @@ class Database {
   }
 }
 
-const getLinks = ({ db }) => {
-  const relationsToUpdate = {};
-
-  db.metadata.forEach((contentType) => {
-    const attributes = contentType.attributes;
-
-    // For each relation type, add the joinTable name to tablesToUpdate
-    Object.values(attributes).forEach((attribute) => {
-      if (!types.isRelation(attribute.type)) return;
-
-      if (attribute.inversedBy) {
-        const invRelation = db.metadata.get(attribute.target).attributes[attribute.inversedBy];
-
-        // Both relations use inversedBy
-        if (invRelation?.inversedBy) {
-          relationsToUpdate[attribute.joinTable.name] = {
-            relation: attribute,
-            invRelation,
-          };
-        }
-      }
-    });
-  });
-
-  return Object.values(relationsToUpdate);
-};
-
 // TODO: move into strapi
 Database.transformContentTypes = transformContentTypes;
 Database.init = async (config) => {
   const db = new Database(config);
-
-  // TODO: Create validations folder for this.
-  const links = getLinks({ db });
-
-  const errorList = [];
-
-  for (const { relation, invRelation } of links) {
-    // Generate the join table name based on the relation target
-    // table and attribute name.
-    const joinTableName = getJoinTableName(
-      db.metadata.get(relation.target).tableName,
-      relation.inversedBy
-    );
-
-    const contentType = db.metadata.get(invRelation.target);
-    const invContentType = db.metadata.get(relation.target);
-
-    // If both sides use inversedBy
-    if (relation.inversedBy && invRelation.inversedBy) {
-      // If the generated join table name is the same as the one assigned in relation.joinTable,
-      // relation is on the inversed side of the bidirectional relation.
-      // and the other is on the owner side.
-      if (joinTableName === relation.joinTable.name) {
-        errorList.push(
-          `Error on attribute "${invRelation.inversedBy}" in model "${invContentType.tableName}"(${invContentType.uid}):` +
-            ` One of the sides of the relationship must be the owning side. You should use mappedBy` +
-            ` instead of inversedBy in the relation "${invRelation.inversedBy}".`
-        );
-      } else {
-        errorList.push(
-          `Error on attribute "${relation.inversedBy}" in model "${contentType.tableName}"(${contentType.uid}):` +
-            ` One of the sides of the relationship must be the owning side. You should use mappedBy` +
-            ` instead of inversedBy in the relation "${relation.inversedBy}".`
-        );
-      }
-    }
-  }
-
-  if (errorList.length > 0) {
-    errorList.forEach((error) => strapi.log.error(error));
-    throw new Error('There are errors in some of your models. Please check the logs above.');
-  }
-
+  await validateDatabase(db);
   return db;
 };
 

packages/core/database/lib/validations/index.js

@@ -0,0 +1,20 @@
+'use strict';
+
+const { validateRelations } = require('./relations');
+
+/**
+ * Validate if the database is in a valid state before starting the server.
+ *
+ * @param {*} db - Database instance
+ */
+async function validateDatabase(db) {
+  const relationErrors = await validateRelations(db);
+  const errorList = [...relationErrors];
+
+  if (errorList.length > 0) {
+    errorList.forEach((error) => strapi.log.error(error));
+    throw new Error('There are errors in some of your models. Please check the logs above.');
+  }
+}
+
+module.exports = { validateDatabase };

packages/core/database/lib/validations/relations/bidirectional.js

@@ -0,0 +1,99 @@
+'use strict';
+
+const types = require('../../types');
+const { getJoinTableName } = require('../../metadata/relations');
+
+const getLinksWithoutMappedBy = (db) => {
+  const relationsToUpdate = {};
+
+  db.metadata.forEach((contentType) => {
+    const attributes = contentType.attributes;
+
+    // For each relation attribute, add the joinTable name to tablesToUpdate
+    Object.values(attributes).forEach((attribute) => {
+      if (!types.isRelation(attribute.type)) return;
+
+      if (attribute.inversedBy) {
+        const invRelation = db.metadata.get(attribute.target).attributes[attribute.inversedBy];
+
+        // Both relations use inversedBy.
+        if (invRelation?.inversedBy) {
+          relationsToUpdate[attribute.joinTable.name] = {
+            relation: attribute,
+            invRelation,
+          };
+        }
+      }
+    });
+  });
+
+  return Object.values(relationsToUpdate);
+};
+
+const isLinkTableEmpty = async (db, linkTableName) => {
+  // If the table doesn't exist, it's empty
+  const exists = await db.getConnection().schema.hasTable(linkTableName);
+  if (!exists) return true;
+
+  const result = await db.getConnection().count('* as count').from(linkTableName);
+  return result.count === 0;
+};
+
+/**
+ * Validates bidirectional relations before starting the server.
+ * - If both sides use inversedBy, one of the sides must switch to mappedBy.
+ *    When this happens, two join tables exist in the database.
+ *    This makes sure you switch the side which does not delete any data.
+ *
+ * @param {*} db
+ * @return {*}
+ */
+const validateBidirectionalRelations = async (db) => {
+  const invalidLinks = getLinksWithoutMappedBy(db);
+  const errorList = [];
+
+  for (const { relation, invRelation } of invalidLinks) {
+    // Generate the join table name based on the relation target
+    // table and attribute name.
+    const inverseJoinTableName = getJoinTableName(
+      db.metadata.get(relation.target).tableName,
+      relation.inversedBy
+    );
+    const joinTableName = getJoinTableName(
+      db.metadata.get(invRelation.target).tableName,
+      invRelation.inversedBy
+    );
+
+    const contentType = db.metadata.get(invRelation.target);
+    const invContentType = db.metadata.get(relation.target);
+
+    // If both sides use inversedBy
+    if (relation.inversedBy && invRelation.inversedBy) {
+      const linkTableEmpty = await isLinkTableEmpty(db, joinTableName);
+      const inverseLinkTableEmpty = await isLinkTableEmpty(db, inverseJoinTableName);
+
+      if (linkTableEmpty) {
+        errorList.push(
+          `Error on attribute "${relation.inversedBy}" in model "${contentType.tableName}"(${contentType.uid}):` +
+            ` One of the sides of the relationship must be the owning side. You should use mappedBy` +
+            ` instead of inversedBy in the relation "${relation.inversedBy}".`
+        );
+      } else if (inverseLinkTableEmpty) {
+        // Its safe to delete the inverse join table
+        errorList.push(
+          `Error on attribute "${invRelation.inversedBy}" in model "${invContentType.tableName}"(${invContentType.uid}):` +
+            ` One of the sides of the relationship must be the owning side. You should use mappedBy` +
+            ` instead of inversedBy in the relation "${invRelation.inversedBy}".`
+        );
+      } else {
+        // Both sides have data in the join table
+      }
+    }
+  }
+
+  return errorList;
+};
+
+module.exports = {
+  validateBidirectionalRelations,
+};

packages/core/database/lib/validations/relations/index.js

@@ -0,0 +1,14 @@
+'use strict';
+
+const { validateBidirectionalRelations } = require('./bidirectional');
+
+/**
+ * Validates if relations data and tables are in a valid state before
+ * starting the server.
+ */
+const validateRelations = async (db) => {
+  const bidirectionalRelationsErrors = await validateBidirectionalRelations(db);
+  return [...bidirectionalRelationsErrors];
+};
+
+module.exports = { validateRelations };