Apex - Governer Limits調(diào)節(jié)器限制

控制器執(zhí)行限制確保在Force.com多租戶平臺(tái)上有效地使用資源。 它是由Salesforce.com指定的對(duì)代碼執(zhí)行有效處理的限制。

什么是調(diào)節(jié)器限制？

我們知道，Apex在多租戶環(huán)境中運(yùn)行; 即單個(gè)資源由所有客戶和組織共享。 因此，有必要確保沒(méi)有人壟斷資源，因此Salesforce.com已經(jīng)創(chuàng)建了一組管理和限制代碼執(zhí)行的限制。 每當(dāng)任何一個(gè)調(diào)節(jié)器限制被越過(guò)，它將拋出錯(cuò)誤，并將停止程序的執(zhí)行。

從開(kāi)發(fā)人員的角度來(lái)看，確保我們的代碼是可擴(kuò)展的并且不應(yīng)該達(dá)到極限是至關(guān)重要的。所有這些限制都適用于每個(gè)交易。 單個(gè)觸發(fā)器執(zhí)行一個(gè)事務(wù)。

正如我們所看到的，觸發(fā)器設(shè)計(jì)模式是一種避免極限誤差的方法。 讓我們看看一些重要的限制。

避免SOQL查詢限制

每個(gè)事務(wù)只能發(fā)出100個(gè)查詢，也就是說(shuō)，當(dāng)代碼發(fā)出超過(guò)100個(gè)SOQL查詢時(shí)，它會(huì)拋出錯(cuò)誤。

例如：

以下是顯示如何達(dá)到SOQL查詢限制的示例：

以下觸發(fā)器遍歷客戶列表，并使用字符串“Ok to Pay”更新子記錄（發(fā)票）描述。

//Heper class:Below code needs o be checked.
public class CustomerTriggerHelper {
	
	public static void isAfterUpdateCall(Trigger.new) {
		createInvoiceRecords(trigger.new);//Method call
		updateCustomerDescription(trigger.new);
	}

	//Method To Create Invoice Records
	public 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 value
				APEX_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 records
	public 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
			}
		}
	} 
}

當(dāng)方法'updateCustomerDescription'被調(diào)用，并且客戶記錄的數(shù)量大于100時(shí)，它將達(dá)到SOQL限制。

為了避免這種情況，不要在For循環(huán)中寫(xiě)入SOQL查詢。 在這種情況下，SOQL查詢已經(jīng)寫(xiě)入for循環(huán)。

下面是我們可以避免DML以及SOQL限制的示例。 我們使用嵌套關(guān)系查詢來(lái)獲取發(fā)票記錄，并使用上下文變量trigger.newMap來(lái)獲取id和Customer記錄的映射。

//SOQL-Good Way to Write Query and avoid limit exception
//Helper Class
public class CustomerTriggerHelper {
	
	public static void isAfterUpdateCall(Trigger.new) {
		createInvoiceRecords(trigger.new);//Method call
		updateCustomerDescription(trigger.new, trigger.newMap);
	}

	//Method To Create Invoice Records
	public 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 value
				APEX_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 records
	public 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 records
		List<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批量調(diào)用

正如我們?cè)谠S多示例中看到的，我們一直在列表中添加修改的記錄，然后對(duì)該列表執(zhí)行DML操作，而不是對(duì)單個(gè)記錄執(zhí)行DML。 下面是同樣的例子。 這是批量觸發(fā)器以及觸發(fā)器幫助器類模式的示例。 您必須先保存幫助程序類，然后保存觸發(fā)器。

注意：將以下代碼粘貼到我們之前創(chuàng)建的“CustomerTriggerHelper”類中。

//Helper Class
public 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_Customer__c objCustomer: customerList) {
            if (objCustomer.APEX_Customer_Status__c == 'Active' && mapOldItToCustomers.get(objCustomer.id).APEX_Customer_Status__c == 'Inactive') {//condition to check the old value and new value
                APEX_Invoice__c objInvoice = new APEX_Invoice__c();
                objInvoice.APEX_Status__c = 'Pending';
                objInvoice.APEX_Customer__c = objCustomer.id;
                InvoiceList.add(objInvoice);
            }
        }
        system.debug('InvoiceList&&&'+InvoiceList);
        insert InvoiceList;//DML to insert the Invoice List in SFDC. This also follows the Bulk pattern
    }

    //Method to update the invoice records
    public static void updateCustomerDescription (List<apex_customer__c> customerList, Map<id, apex_customer__c> newMapVariable, Map<id, apex_customer__c> oldCustomerMap) {
        List<apex_customer__c> customerListWithInvoice = [SELECT id, Name,(SELECT Id, Name, APEX_Description__c FROM Invoices__r) FROM APEX_Customer__c WHERE Id IN :newMapVariable.keySet()];//Query will be for only one time and fetches all the records
        List<apex_invoice__c> invoiceToUpdate = new List<apex_invoice__c>();
		List<apex_invoice__c> invoiceFetched = new List<apex_invoice__c>();
		invoiceFetched = customerListWithInvoice[0].Invoices__r;
		system.debug('invoiceFetched'+invoiceFetched);
        system.debug('customerListWithInvoice****'+customerListWithInvoice);
		for (APEX_Customer__c objCust: customerList) {
			system.debug('objCust.Invoices__r'+objCust.Invoices__r);
            if (objCust.APEX_Active__c == true && oldCustomerMap.get(objCust.id).APEX_Active__c == false) {
				for (APEX_Invoice__c objInv: invoiceFetched) {
					system.debug('I am in For Loop'+objInv);
					objInv.APEX_Description__c = 'OK To Pay';
					invoiceToUpdate.add(objInv);//Add the modified records to List
				}
			}
        }
		system.debug('Value of List ***'+invoiceToUpdate);
        update invoiceToUpdate;//This statement is Bulk DML which performs the DML on List and avoids the DML Governor limit
    } 
}

//Trigger Code for this class: Paste this code in 'Customer_After_Insert' trigger on Customer Object
trigger Customer_After_Insert on APEX_Customer__c (after update) {
    CustomerTriggerHelper.isAfterUpdateCall(Trigger.new, trigger.newMap, trigger.oldMap);//Trigger calls the helper class and does not have any code in Trigger
}

其他Salesforce Governor限制

以下是一些重要的Salesforce Governor限制，我們需要記住。 你可以檢查其他Salesforce Governor限制以及使用Salesdorce.com Apex開(kāi)發(fā)人員指南。