问题描述
Documents.update(
{_id: Session.get("current_document_id")},
{$push: {schema: {type: "text", size: size, name: name, label: label}}}
);
上面的查询是一个 Meteor 集合,'Documents.update' 映射到 MongoDB 文档 (http://docs.mongodb.org/manual/applications/update/) 中的 'db.documents.update'.通过该查询,我可以在主文档中添加一个架构文档.子文档存储在一个数组中:
The above query is a Meteor collection, and 'Documents.update' maps to 'db.documents.update' in MongoDB documentation (http://docs.mongodb.org/manual/applications/update/). With that query I can add a schema document inside the main document. Subdocuments are stored in an array:
Document:
schema:
array:
{type: "text", size: 6, name: "first_name", label: "First name"},
{type: "text", size: 6, name: "last_name", label: "Last name"}
我想用这个查询修改子文档的名称和大小属性:
I want to modify the name and size attributes of the subdocuments with this query:
Documents.update(
{_id: Session.get("current_document_id"), 'schema' : "first_name"},
{$push: {schema: {type: "text", size: 7, name: name, label: "First Name2"}}}
);
但该操作直接在模式下追加一个新对象并删除数组:
But that operation append a new object directly under schema and deletes the array:
Document:
schema:
{type: "text", size: 7, name: "first_name", label: "First Name2"}
如何修改查询以更改属性以避免此问题?查询后我想要这个文件:
How can I modify the query to change the attributes avoiding this issue? After the query I would like to have this document:
Document:
schema:
array:
{type: "text", size: 7, name: "first_name", label: "First name2"},
{type: "text", size: 6, name: "last_name", label: "Last name"}
推荐答案
您可以使用使用 $
位置运算符,用于标识选择器中匹配的数组元素,如下所示:
You can update an existing array element using a $set
operation that uses the $
positional operator to identify the array element matched in the selector like this:
Documents.update(
{_id: Session.get("current_document_id"), 'schema.name': "first_name"},
{$set: {'schema.$': {type: "text", size: 7, name: name, label: "First Name2"}}}
);
这会将匹配的 schema
元素替换为包含在 $set
对象中的元素.
This will replace the matched schema
element with the one included in the $set
object.
如果您只想更新目标 schema
元素的各个字段,您可以使用点表示法.例如,仅更新 size
和 name
字段:
If you only want to update individual fields of the targeted schema
element, you can use dot notation. For example, to only update the size
and name
fields:
Documents.update(
{_id: Session.get("current_document_id"), 'schema.name': "first_name"},
{$set: {'schema.$.size': 7, 'schema.$.name': name}}
);
这篇关于更新包含在 MongoDB 文档中的数组中的子文档的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!