【问题标题】：ArangoDB / AQL Update Nested DocumentsArangoDB / AQL 更新嵌套文档
【发布时间】：2018-02-23 20:29:34
【问题描述】：

给定以下文档结构：

{
  "_key": "abc",
  "_id": "abc",
  "label": "Company ABC",
  "departments": [
    {
      "name": "Department 123",
      "id": "123"
    },
    {
      "name": "Department 456",
      "id": "456"
    }
  ]
}

你能告诉我为什么下面的查询不起作用吗？错误消息是“缺少文档密钥”。我在另一个 SO (ArangoDB AQL: Update single object in embedded array) 中发现了一个更长更复杂的解决方法，但我很好奇更简单的查询到底有什么问题。

FOR c IN company
  FOR d in c.deparments
    FILTER d.id == “456”
    UPDATE d WITH { name: “Department 789” } IN company
RETURN d

【问题讨论】：

标签： arangodb aql

【解决方案1】：

目前，我只知道如何更新 ArangoDB 中的顶级属性。虽然我希望将来有替代方案引起我的注意，但这里有一些适合您的方案的选项。

使用 MERGE 更新

在此示例中，我们通过重写数组并在满足条件时使用MERGE 函数来更新顶级departments 属性。

LET company = DOCUMENT("companies/abc")

UPDATE company WITH {
  departments:
   (FOR department IN company.departments
     RETURN department.id == "456" ?
       MERGE(department, {name: "Department 789"}) : department)
} IN companies

使用替代数据模型

以上示例假设部门数据嵌入在公司文档中。考虑以下几点：

“公司”集合

{
  "_key": "abc",
  "_id": "companies/abc",
  "label": "Company ABC"
}

“部门”集合（单独的文档）

{
  "_key": "456",
  "_id": "departments/456",
  "company": "companies/abc",
  "name": "Department 456"
}

{
  "_key": "123",
  "_id": "departments/123",
  "company": "companies/abc",
  "name": "Department 123"
}

让公司 #ABC 与部门：

LET company = DOCUMENT("companies/abc")

LET departments =
  (FOR department IN departments
    FILTER department.company == company._id
    RETURN department)

RETURN MERGE(company, {departments})

结果：

{
  "_id": "companies/abc",
  "_key": "abc",
  "label": "Company ABC",
  "departments": [
    {
      "_key": "456",
      "_id": "departments/456",
      "company": "companies/abc",
      "name": "Department 456"
    },
    {
      "_key": "123",
      "_id": "departments/123",
      "company": "companies/abc",
      "name": "Department 123"
    }
  ]
}

更新部门#456：

LET department = DOCUMENT("departments/456")

UPDATE department WITH {name: "Department 789"} IN departments

请注意，您需要在departments 集合中的company 属性上添加索引。您可以在此处获取有关索引的详细信息：

https://docs.arangodb.com/3.3/Manual/Indexing/WhichIndex.html

您必须权衡这两种模型的优缺点。

【讨论】：

谢谢！您的第一个解决方案与我原来的 AQL 类似，但更简洁。
“我希望将来能引起我的注意” - 这个话题有更新吗？我有同样的问题，我想知道最佳做法。