Exists query in Elasticsearch - Mini Project: Build & Apply

Using Exists Query in Elasticsearch

📖 Scenario: You have a collection of documents representing books in a library. Some books have a publisher field, but others do not. You want to find all books that have a publisher field set.

🎯 Goal: Build an Elasticsearch query using the exists query to find all documents where the publisher field exists.

📋 What You'll Learn

Create an index mapping with fields title and publisher

Add sample documents with and without the publisher field

Write an exists query to find documents where publisher exists

Print the query JSON to verify correctness

💡 Why This Matters

🌍 Real World

Exists queries help find documents that have certain information filled in, like finding all books that have a publisher listed.

💼 Career

Knowing how to write exists queries is useful for data filtering and search tasks in roles like data analyst, backend developer, or search engineer.

1

Create sample documents

Create a variable called documents that contains a list of three dictionaries representing books. The first book has title "Book A" and publisher "Pub1". The second book has title "Book B" without a publisher. The third book has title "Book C" and publisher "Pub3".

Elasticsearch

# Create a list called documents with three book dictionaries
# Your code here

Need a hint?

Use a list of dictionaries. Some dictionaries have the publisher key, some do not.

2

Create the exists query

Create a variable called exists_query that contains a dictionary representing an Elasticsearch exists query checking for the field publisher.

Elasticsearch

documents = [
    {"title": "Book A", "publisher": "Pub1"},
    {"title": "Book B"},
    {"title": "Book C", "publisher": "Pub3"}
]
# Create an exists query for field 'publisher'
# Your code here

Need a hint?

The exists query uses a dictionary with key field set to the field name.

3

Combine documents and query in a search body

Create a variable called search_body that contains a dictionary with the key query set to the exists_query value inside it.

Elasticsearch

documents = [
    {"title": "Book A", "publisher": "Pub1"},
    {"title": "Book B"},
    {"title": "Book C", "publisher": "Pub3"}
]

exists_query = {
    "query": {
        "exists": {
            "field": "publisher"
        }
    }
}

# Create search_body dictionary with the query key set to exists_query['query']
# Your code here

Need a hint?

Use the query key and assign it the value inside exists_query["query"].

4

Print the search query JSON

Write a print statement to display the search_body variable.

Elasticsearch

documents = [
    {"title": "Book A", "publisher": "Pub1"},
    {"title": "Book B"},
    {"title": "Book C", "publisher": "Pub3"}
]

exists_query = {
    "query": {
        "exists": {
            "field": "publisher"
        }
    }
}

search_body = {
    "query": exists_query["query"]
}

# Print the search_body dictionary
# Your code here

Need a hint?

Use print(search_body) to display the query dictionary.