如何从 salesforce 查询中的查找中获取信息

Question

I have a custom salesforce object Installation__c and it has a custom field Product__c which is a lookup to a custom object Product__c I am trying to get the fields from the child object using these query:

public with sharing class InstallationController {
    @AuraEnabled
    public static List<Installation__c> getItems() {
        // Perform isAccessible() checking first, then
        return [SELECT Id, Name, Installation_Display_Name__c, Product__c, Status__c, (SELECT Product__c.Name FROM Product__c)  FROM Installation__c];
    }
}

我得到错误：

Didn't understand relationship 'Product__c' in FROM part of query call. If you are attempting to use a custom relationship, be sure to append the '__r' after the custom relationship name. Please reference your WSDL or the describe call for the appropriate names.

我尝试将查询更改为FROM Product__r和 FROM Product__c__r但似乎都不起作用，我该如何修复我的查询？

Answer 1

如果您正在向上或向下遍历关系层次结构，则 __c 后缀将变为 __r（r 表示“关系”），直到您最终到达要查找的字段（如果它是自定义字段，则仍以 __c 结尾）。 所以在你的情况下，它将是

public with sharing class InstallationController {
    @AuraEnabled
    public static List<Installation__c> getItems() {
        // Perform isAccessible() checking first, then
        return [SELECT Id, Name, Installation_Display_Name__c, Product__r.Name, Status__c FROM Installation__c];
    }
}

所以，这里的变化是，对于你必须使用Product__r.Name的关系

Answer 2

单击已查找的 object 上的关系。 复制添加__r的关系名称

这个例子是Test_Drives__r