How to search a value in an array of objects in MongoDB? There are some techniques to search a value in an array of Objects. In this article, we will explore how to search through arrays of objects in MongoDB using a variety of techniques from basic to complex.
Let’s consider a collect student with some documents have arrays and I will use this collection to demonstrate the examples
#Create Collection
db.student.insertMany([
{
_id:1,
student_Info: [
{“name”:”Alice”, “age”: 23, “batch”: 2023,
“address”:[
{“city”:”Atlanta”, “street”: “XYZ”}
]
} ],
course_Info: [ {course:”Python”, credit_hours: 4} ]
},
{
_id:2,
student_Info: [
{“name”:”Ian”, “age”: 21, “batch”: 2021,
“address”:[
{“city”:”Atlanta”, “street”: “ABC”}
]
} ],
course_Info: [ {course:”MongoDB”, credit_hours: 3} ]
},
{
_id:3,
student_Info: [
{“name”:”Tyler”, “age”: 22, “batch”: 2023,
“address”:[
{“city”:”Georgia”, “street”: “LMN”}
]
} ],
course_Info: [ {course:”Java”, credit_hours: 4} ]
}
])
1. MongoDB Search in Array Using Basic Query
The most common way to search through arrays of objects in MongoDB is to use a basic querying method.
For example, we have an array of student_Info in the collection student which contains the name field, and we want to find the documents where the array object field name has the value Ian. The following query searches the array student_info where the name is Ian and when the condition is true, it returns all the documents.
#Usage of basic query
db.student.find({ “student_Info.name”: “Ian” })
The output is yielded where the array student_Info has the name equal to Ian.
2. With Regular Expression Query
Here, we have another basic technique to search within arrays of objects which is using regular expressions.
For example, we have an array object course_Info in the collection student that contains the field course. We want to search for all students who have a course with a title that starts with Py. For this, we have the following query which searches the course_Info array and contains at least one object with a course property that matches the regular expression /^Py/.
#Usage of Regular Expression Query
db.student.find({ “course_Info.course”: /^Py/ })
The output yielded one document that satisfies the given regular expression to the array object.
3. With Multiple Fields Query
In addition to the prior examples, we can also search within arrays of objects by specifying multiple fields to search for.
For example, each student_Info array is specified with the fields name and age. Now, we have the following query to search for the student_Info array which contains at least one object with a name property equal to Alice and an age property equal to 23.
#Usage of Multiple Fields Query
db.student.find({ “student_Info.name”: “Alice”, “student_Info.age”: 23 })
The document is retrieved in the output which contains both the field with the value in the array.
4. With $elemMatch Query
Sometimes, we need to search for documents where multiple conditions must be satisfied within the same object in the array.
To achieve this, we have the $elemMatch operator which is used to specify that all the specified criteria must match within the same element of the array.
For example, we have an array student_Info which contains multiple fields. Here we have a query where the $elemMatch operator is called to search the documents that contain an element in the student_Info array that matches the specified criteria. The criteria include the name Tyler, an age of 22, and a batch number greater than 2022.
#Usage of $elemMatch Query
db.student.find({ student_Info: { $elemMatch: { name: “Tyler”, age: 22, batch: { $gt: 2022 } } } })
The output is fetched which matches the specified criteria.
5. With Nested Object Query
Further, the objects nested within arrays of objects can also be searched.
For example, we have an array student_Info which contains another array address. We want to search from the nested array address. For this, we have a following query that searches the nested array address with a city property equal to Atlanta.
#Usage of Nested Object Query
db.student.find({ “student_Info.name”: “Ian”, “student_Info.address.city”: “Atlanta” })
The expected output is retrieved below from the above query of the nested array.
6. With Projection Query
Finally, we have an alternate option which is a projection to filter out the array if we want to return only the matching objects in an array.
For example, we want to search from the course_Info array object containing a course field and a credit_hours field. We have the following query which searches through the “course_Info” array for any objects that contain a credit_hours field with the value 4. It then uses projection to return only the matching objects with the specified field.
#Usage of Projection Query
db.student.find({ “course_Info.credit_hours”: 4 }, { “course_Info.$”: 1 })
The output shows the documents whose credit_hours are 4 in the course_Info array.
7. Conclusion
In conclusion, searching within arrays of objects in MongoDB can be achieved using various techniques discussed above. We can use these examples as a jumping-off point for more complicated queries.
More queries about this topic can be solved from here.
How to search a value in an array of objects in MongoDB? There are some techniques to search a value in an array of Objects. In this article, we will explore how to search through arrays of objects in MongoDB using a variety of techniques from basic to complex. Let’s consider a collect student with Read More MongoDB