Cleanup delete schema (#1604)

* Some cleanup for deleting one schema

* tidyness

* Remove _allCollections as Parse Server doesn't need it.

src/Controllers/DatabaseController.js

@@ -381,11 +381,7 @@ DatabaseController.prototype.mongoFind = function(className, query, options = {}
 // Returns a promise.
 DatabaseController.prototype.deleteEverything = function() {
   this.schemaPromise = null;
-
-  return this.adapter.allCollections().then(collections => {
-    let promises = collections.map(collection => collection.drop());
-    return Promise.all(promises);
-  });
+  return this.adapter.deleteAllSchemas();
 };
 
 // Finds the keys in a query. Returns a Set. REST format only
@@ -652,21 +648,19 @@ DatabaseController.prototype.find = function(className, query, {
 
 DatabaseController.prototype.deleteSchema = function(className) {
   return this.collectionExists(className)
-    .then(exist => {
-      if (!exist) {
-        return Promise.resolve();
+  .then(exist => {
+    if (!exist) {
+      return Promise.resolve();
+    }
+    return this.adapter.adaptiveCollection(className)
+    .then(collection => collection.count())
+    .then(count => {
+      if (count > 0) {
+        throw new Parse.Error(255, `Class ${className} is not empty, contains ${count} objects, cannot drop schema.`);
       }
-      return this.adapter.adaptiveCollection(className)
-        .then(collection => {
-          return collection.count()
-            .then(count => {
-              if (count > 0) {
-                throw new Parse.Error(255, `Class ${className} is not empty, contains ${count} objects, cannot drop schema.`);
-              }
-              return collection.drop();
-            })
-        })
+      return this.adapter.deleteOneSchema(className);
     })
+  });
 }
 
 DatabaseController.prototype.addPointerPermissions = function(schema, className, operation, query, aclGroup = []) {

src/Controllers/SchemaController.js

@@ -134,7 +134,7 @@ function validateCLP(perms, fields) {
       }
       return;
     }
-    
+
     Object.keys(perms[operation]).forEach((key) => {
       verifyPermissionKey(key);
       let perm = perms[operation][key];
@@ -543,7 +543,7 @@ class SchemaController {
       if (this.data[className][fieldName].type == 'Relation') {
         //For relations, drop the _Join table
         return database.adapter.deleteFields(className, [fieldName], [])
-        .then(() => database.adapter.dropCollection(`_Join:${fieldName}:${className}`));
+        .then(() => database.adapter.deleteOneSchema(`_Join:${fieldName}:${className}`));
       }
 
       const fieldNames = [fieldName];
@@ -632,7 +632,7 @@ class SchemaController {
         found = true;
       }
     }
-     
+
     if (found) {
       return Promise.resolve();
     }
@@ -640,7 +640,7 @@ class SchemaController {
     // No matching CLP, let's check the Pointer permissions
     // And handle those later
     let permissionField = ['get', 'find'].indexOf(operation) > -1 ? 'readUserFields' : 'writeUserFields';
-    
+
     // Reject create when write lockdown
     if (permissionField == 'writeUserFields' && operation == 'create') {
       throw new Parse.Error(Parse.Error.OPERATION_FORBIDDEN,