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Nested objects and arrays

Dot notation, matching array contents, and the trap everyone hits.

By the end: Query inside sub-documents and arrays of objects correctly.

1. Dot notation into nested objects

   Query fields inside nested MongoDB objects with dot notation: { "address.city": "Bangalore" }, and why the path needs quotes.

2. Querying arrays

   How MongoDB matches arrays: a scalar match tests every element, and $all requires all of your values to be present.

3. Arrays of objects

   Querying arrays of sub-documents in MongoDB with dot notation, and what a match on "orders.status" actually tests.

4. $elemMatch and the multi-condition trap

   The classic MongoDB array trap: two conditions on an array of objects can match different elements. $elemMatch is the fix.

• Dot notation into a nested object
• Array contains a value
• $all - every value required
• The $elemMatch trap