Apex - Governer Limits调节器限制

由 kaikai0220 创建，youj 最后一次修改 2016-12-12 控制器执行限制确保在Force.com多租户平台上有效地使用资源。 它是由Salesforce.com指定的对代码执行有效处理的限制。 什么是调节器限制？我们知道，Apex在多租户环境中运行; 即单个资源由所有客户和组织共享。 因此，有必要确保没有人垄断资源，因此Salesforce.com已经创建了一组管理和限制代码执行的限制。 每当任何一个调节器限制被越过，它将抛出错误，并将停止程序的执行。 从开发人员的角度来看，确保我们的代码是可扩展的并且不应该达到极限是至关重要的。所有这些限制都适用于每个交易。 单个触发器执行一个事务。 正如我们所看到的，触发器设计模式是一种避免极限误差的方法。 让我们看看一些重要的限制。 避免SOQL查询限制每个事务只能发出100个查询，也就是说，当代码发出超过100个SOQL查询时，它会抛出错误。 例如： 以下是显示如何达到SOQL查询限制的示例： 以下触发器遍历客户列表，并使用字符串“Ok to Pay”更新子记录（发票）描述。//Heper class:Below code needs o be checked.public class CustomerTriggerHelper {public static void isAfterUpdateCall(Trigger.new) {createInvoiceRecords(trigger.new);//Method callupdateCustomerDescription(trigger.new);}//Method To Create Invoice Recordspublic static void createInvoiceRecords (List<apex_customer__c> customerList) {for (APEX_Customer__c objCustomer: customerList) {if (objCustomer.APEX_Customer_Status__c == 'Active' && trigger.oldMap.get(objCustomer.id).APEX_Customer_Status__c == 'Inactive') {//condition to check the old value and new valueAPEX_Invoice__c objInvoice = new APEX_Invoice__c();objInvoice.APEX_Status__c = 'Pending';InvoiceList.add(objInvoice);}}insert InvoiceList;//DML to insert the Invoice List in SFDC}//Method to update the invoice recordspublic static updateCustomerDescription (List<apex_customer__c> customerList) {for (APEX_Customer__c objCust: customerList) {List<apex_invoice__c> invList = [SELECT Id, Name, APEX_Description__c FROM APEX_Invoice__c WHERE APEX_Customer__c = :objCust.id];//This query will fire for the number of records customer list has and will hit the governor limit when records are more than 100 for (APEX_Invoice__c objInv: invList) {objInv.APEX_Description__c = 'OK To Pay';update objInv;//Update invoice, this will also hit the governor limit for DML if large number(150) of records are there}}} }当方法'updateCustomerDescription'被调用，并且客户记录的数量大于100时，它将达到SOQL限制。 为了避免这种情况，不要在For循环中写入SOQL查询。 在这种情况下，SOQL查询已经写入for循环。 下面是我们可以避免DML以及SOQL限制的示例。 我们使用嵌套关系查询来获取发票记录，并使用上下文变量trigger.newMap来获取id和Customer记录的映射。//SOQL-Good Way to Write Query and avoid limit exception//Helper Classpublic class CustomerTriggerHelper {public static void isAfterUpdateCall(Trigger.new) {createInvoiceRecords(trigger.new);//Method callupdateCustomerDescription(trigger.new, trigger.newMap);}//Method To Create Invoice Recordspublic static void createInvoiceRecords (List<apex_customer__c> customerList) {for (APEX_Customer__c objCustomer: customerList) {if (objCustomer.APEX_Customer_Status__c == 'Active' && trigger.oldMap.get(objCustomer.id).APEX_Customer_Status__c == 'Inactive') {//condition to check the old value and new valueAPEX_Invoice__c objInvoice = new APEX_Invoice__c();objInvoice.APEX_Status__c = 'Pending';InvoiceList.add(objInvoice);}}insert InvoiceList;//DML to insert the Invoice List in SFDC}//Method to update the invoice recordspublic static updateCustomerDescription (List<apex_customer__c> customerList, Map<id, apex_customer__c> newMapVariable) {List<apex_customer__c> customerListWithInvoice = [SELECT id, Name,(SELECT Id, Name, APEX_Description__c FROM APEX_Invoice__r) FROM APEX_Customer__c WHERE Id IN :newMapVariable.keySet()];//Query will be for only one time and fetches all the recordsList<apex_invoice__c> invoiceToUpdate = new List<apex_invoice__c>();for (APEX_Customer__c objCust: customerList) {for (APEX_Invoice__c objInv: invList) {objInv.APEX_Description__c = 'OK To Pay';invoiceToUpdate.add(objInv);//Add the modified records to List}}update invoiceToUpdate;} } DML批量调用正如我们在许多示例中看到的，我们一直在列表中添加修改的记录，然后对该列表执行DML操作，而不是对单个记录执行DML。 下面是同样的例子。 这是批量触发器以及触发器帮助器类模式的示例。 您必须先保存帮助程序类，然后保存触发器。 注意：将以下代码粘贴到我们之前创建的“CustomerTriggerHelper”类中。//Helper Classpublic class CustomerTriggerHelper { public static void isAfterUpdateCall(List<apex_customer__c> customerList, Map<id, apex_customer__c> mapIdToCustomers, Map<id, apex_customer__c> mapOldItToCustomers) { createInvoiceRecords(customerList, mapOldItToCustomers);//Method call updateCustomerDescription(customerList,mapIdToCustomers, mapOldItToCustomers); } //Method To Create Invoice Records public static void createInvoiceRecords (List<apex_customer__c> customerList, Map<id, apex_customer__c> mapOldItToCustomers) { List<apex_invoice__c> InvoiceList = new List<apex_invoice__c>(); List<apex_customer__c> customerToInvoice = [SELECT id, Name FROM APEX_Customer__c LIMIT 1]; for (APEX_