MongoDB数组元素更新查询不符合预期，请求技术支持

Let's break down what's going wrong with your current query and fix it to match your exact requirements.

Your Core Requirements #

You need to update documents only when all these conditions are met:

• The courses array contains an element with courseId: "4" and that same element does not have a courseProgress field
• The document's completionStatus is not "F"
• The document's enterpriseId is 13

Why Your Current Query Fails #

Your existing query splits the courses array conditions into separate checks:

'courses.courseId':'4', 
'courses':{$elemMatch:{'courseProgress':{$exists:false}}}

MongoDB interprets this as:

"Find documents where the courses array has any element with courseId: "4", and the courses array has any element without courseProgress"

These don't have to be the same element! The positional $ operator then picks the first array element that matches any of the array conditions—so in your sample document, it's updating the courseId: "4" element (which has courseProgress: 100), which violates your requirements.

The Corrected Query #

To fix this, use $elemMatch to group both courseId and courseProgress conditions together, ensuring they apply to the same array element:

db.table.update(
  {
    enterpriseId: 13,
    completionStatus: { $ne: "F" },
    courses: {
      $elemMatch: {
        courseId: "4",
        courseProgress: { $exists: false }
      }
    }
  },
  {
    $set: {
      "courses.$.courseId": "45",
      "courses.$.courseName": "testCourse"
    }
  },
  { multi: true }
)

How This Works #

• The $elemMatch clause ensures we only match documents where one single element in the courses array meets both criteria: courseId: "4" and no courseProgress field exists.
• The positional $ operator now correctly targets that specific matching element, so only the element you want is updated.
• Your sample document won't be matched at all (since its courseId: "4" element has courseProgress: 100), which aligns perfectly with your needs.

内容的提问来源于stack exchange，提问作者Abhishek Kumar