AZ CLI query filter on multiple properties using &&

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05-09-2024

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Filtering Azure CLI Results: Mastering the Art of AND with &&

The Azure CLI (az) offers powerful filtering capabilities using JMESPath, a query language that allows you to extract and manipulate JSON data. This article explores how to efficiently filter Azure CLI results using the && operator to perform AND operations on multiple properties.

Understanding the Challenge: Filtering by Multiple Criteria

You're likely looking to pinpoint specific Azure resources based on multiple criteria – for example, finding the subscription with a specific ID within a specific tenant.

Let's break down the user's original issue:

• Goal: Find the subscription with ID 'ABC' and tenant ID '123'.
• Problem: Using && (AND) in the JMESPath query doesn't return the expected results. Instead of returning the desired subscription, it returns an empty array ([]).

Why is this happening?

The core misunderstanding lies in how && functions within JMESPath, especially when used with the ? operator for filtering. Let's delve deeper.

JMESPath Logic: Unraveling the Mystery of &&

JMESPath operates on a collection of JSON objects. The ? operator filters this collection by applying conditions. When using && inside a ? expression, it doesn't directly combine filter conditions. Instead, it performs a logical AND on the truthiness of each sub-expression.

Practical Example:

Consider a list of users with id and active properties:

[
    {"id": 1, "active": true},
    {"id": 2, "active": false},
    {"id": 3, "active": true}
]

The JMESPath expression [?id == 1 && active == true] will:

1. Evaluate id == 1 for each user.
2. Evaluate active == true for each user.
3. For each user, perform a logical AND on the results of steps 1 and 2.
4. Return only users where the AND operation evaluates to true.

In this case, the expression would return only the user with id 1 because both conditions are true for that user.

The Solution: Leveraging JMESPath for Effective Filtering

To achieve the desired filtering, you should not combine && and ? directly. Instead, focus on filtering each property individually and then combining the filtered results.

Correct Approach:

1. Filter by subscription ID: [?id == 'ABC']
2. Filter by tenant ID: [?tenantId == '123']
3. Combine results using the [] operator: [?id == 'ABC'] | [?tenantId == '123']

Complete JMESPath Query:

az account list --query "[?id == 'ABC'] | [?tenantId == '123']" --output json

This query first filters the list by subscription ID, then filters the results by tenant ID, effectively producing a list of subscriptions that meet both criteria.

Additional Considerations

• Understanding JMESPath Syntax: Take the time to understand JMESPath syntax, including the ?, [], and | operators. This will empower you to write more complex and efficient queries.
• Resource Documentation: Always refer to the Azure CLI documentation for specific commands, resource properties, and filtering options.

Conclusion

Filtering Azure CLI results with multiple criteria requires a precise understanding of JMESPath syntax. By leveraging the appropriate operators and filtering strategies, you can efficiently refine your Azure resource management operations and obtain the desired results. Remember to experiment with different query formats to discover the most efficient and readable solutions for your specific use cases.