Nested queries for nested objects in Elasticsearch - Mini Project: Build & Apply

Nested queries for nested objects

📖 Scenario: You work with a bookstore database in Elasticsearch. Each book document has a nested field called authors that stores multiple authors with their name and age. You want to find books where at least one author is younger than 40.

🎯 Goal: Build an Elasticsearch query using nested queries to find books with authors younger than 40.

📋 What You'll Learn

Create an index mapping with a nested authors field

Add a config variable for the age threshold

Write a nested query to find books with authors younger than the threshold

Print the final query JSON

💡 Why This Matters

🌍 Real World

Nested queries are used when you have complex data with arrays of objects, like books with multiple authors, and you want to search inside those nested objects.

💼 Career

Many jobs working with Elasticsearch require building nested queries to filter or search data accurately inside nested fields.

1

Create index mapping with nested authors

Create a variable called mapping that holds the Elasticsearch index mapping JSON. It should define a books index with a authors field of type nested. Each author has name (text) and age (integer).

Elasticsearch

# Create the mapping variable with nested authors field
# Your code here

Need a hint?

Use a dictionary with mappings and properties. The authors field must have "type": "nested".

2

Set age threshold variable

Create a variable called age_threshold and set it to 40. This will be used to find authors younger than this age.

Elasticsearch

mapping = {
    "mappings": {
        "properties": {
            "title": {"type": "text"},
            "authors": {
                "type": "nested",
                "properties": {
                    "name": {"type": "text"},
                    "age": {"type": "integer"}
                }
            }
        }
    }
}

# Create age_threshold variable and set to 40
# Your code here

Need a hint?

Just create a variable age_threshold and assign the number 40.

3

Write nested query for authors younger than threshold

Create a variable called query that holds an Elasticsearch nested query. It should search the authors nested field for authors with age less than age_threshold. Use nested query with path set to authors and a range query on authors.age with lt set to age_threshold.

Elasticsearch

mapping = {
    "mappings": {
        "properties": {
            "title": {"type": "text"},
            "authors": {
                "type": "nested",
                "properties": {
                    "name": {"type": "text"},
                    "age": {"type": "integer"}
                }
            }
        }
    }
}
age_threshold = 40

# Create the nested query in variable 'query' to find authors younger than age_threshold
# Your code here

Need a hint?

Use a dictionary with query key, inside it a nested query with path and a range query on authors.age.

4

Print the final query JSON

Write a print statement to display the query variable.

Elasticsearch

mapping = {
    "mappings": {
        "properties": {
            "title": {"type": "text"},
            "authors": {
                "type": "nested",
                "properties": {
                    "name": {"type": "text"},
                    "age": {"type": "integer"}
                }
            }
        }
    }
}
age_threshold = 40

query = {
    "query": {
        "nested": {
            "path": "authors",
            "query": {
                "range": {
                    "authors.age": {
                        "lt": age_threshold
                    }
                }
            }
        }
    }
}

# Print the query variable
# Your code here

Need a hint?

Use print(query) to show the query dictionary.