Filter Query Guide

Following example shows commonly used filter query operators with descriptions and usage examples.

Equality and Comparison Operators

Operator	Description	Example
$eq	Matches values that are equal to a specified value.	{ "status": { "$eq": "A" } }
$ne	Matches values not equal to a specified value.	{ "status": { "$ne": "A" } }
$gt	Matches values greater than a specified value.	{ "age": { "$gt": 25 } }
$gte	Matches values greater than or equal to a specified value.	{ "age": { "$gte": 18 } }
$lt	Matches values less than a specified value.	{ "age": { "$lt": 65 } }
$lte	Matches values less than or equal to a specified value.	{ "age": { "$lte": 30 } }

Logical Operators

Operator	Description	Example
$and	Joins query clauses with logical AND.	{ "$and": [ { "age": { "$gt": 18 } }, { "age": { "$lt": 60 } } ] }
$or	Joins query clauses with logical OR.	{ "$or": [ { "status": "A" }, { "qty": { "$lt": 30 } } ] }
$nor	Joins query clauses with NOR.	{ "$nor": [ { "price": 1.99 }, { "qty": { "$lt": 20 } } ] }
$not	Inverts the effect of a query expression.	{ "price": { "$not": { "$gt": 1.99 } } }

Element Operators

Operator	Description	Example
$exists	Matches documents with the specified field.	{ "middle_name": { "$exists": true } }
$type	Matches documents where field is of specified type.	{ "score": { "$type": "double" } }

Evaluation Operators

Operator	Description	Example
$expr	Allows use of aggregation expressions in filters.	{ "$expr": { "$gt": [ "$spent", "$budget" ] } }
$regex	Matches strings using regular expressions.	{ "name": { "$regex": "^J" } }
$text	Performs text search on indexed fields.	{ "$text": { "$search": "coffee" } }
$mod	Matches numbers divisible by a specified value.	{ "qty": { "$mod": [ 4, 0 ] } }

Array Operators

Operator	Description	Example
$in	Matches any of the values specified in an array.	{ "status": { "$in": ["A", "B"] } }
$nin	Matches none of the values specified in an array.	{ "status": { "$nin": ["D", "E"] } }
$all	Matches arrays that contain all elements specified.	{ "tags": { "$all": ["red", "blank"] } }
$elemMatch	Matches documents with array fields matching multiple conditions.	{ "results": { "$elemMatch": { "$gt": 80, "$lt": 85 } } }
$size	Matches arrays with the specified number of elements.	{ "tags": { "$size": 3 } }

Note: All examples use MongoDB Extended JSON format. Make sure to escape { } with {{ }} in Zig.

Options Query Guide

Following example shows common options available for MongoDB query operations (e.g., find, aggregate, count_documents, etc.) with descriptions and examples.

General Query Options

Option	Type	Description	Example
limit	Integer	Limits the number of documents returned.	{ "limit": 10 }
skip	Integer	Skips the specified number of documents before returning.	{ "skip": 5 }
sort	Document	Specifies the sort order for results.	{ "sort": { "age": -1 } }
projection	Document	Limits the fields returned in each document.	{ "projection": { "name": 1, "_id": 0 } }
hint	String / Document	Forces MongoDB to use a specific index.	{ "hint": "age_1" } or { "hint": { "age": 1 } }
comment	String	Attaches a comment to the query for debugging and profiling.	{ "comment": "user search operation" }

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Cursor Behavior

Option	Type	Description	Example
batchSize	Integer	Specifies the number of documents returned per batch.	{ "batchSize": 100 }
noCursorTimeout	Boolean	Prevents server from closing cursor after timeout period.	{ "noCursorTimeout": true }
tailable	Boolean	Makes cursor tail the oplog or capped collection.	{ "tailable": true }
awaitData	Boolean	Use with tailable to wait for new data before returning.	{ "awaitData": true }

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Aggregation-Specific Options

Option	Type	Description	Example
allowDiskUse	Boolean	Allows MongoDB to use temporary disk files during aggregation.	{ "allowDiskUse": true }
maxTimeMS	Integer	Specifies the maximum execution time in milliseconds.	{ "maxTimeMS": 5000 }
collation	Document	Specifies collation (e.g., case-insensitivity).	{ "collation": { "locale": "en", "strength": 1 } }
bypassDocumentValidation	Boolean	Bypasses schema validation when performing write stages.	{ "bypassDocumentValidation": true }
readConcern	Document	Specifies the level of isolation for read operations.	{ "readConcern": { "level": "majority" } }

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Count/Find Options (Specific)

Option	Type	Description	Example
readPreference	Document	Specifies preferred replica read behavior.	{ "readPreference": { "mode": "secondary" } }
max	Document	Specifies upper bound index key values for the query.	{ "max": { "age": 30 } }
min	Document	Specifies lower bound index key values for the query.	{ "min": { "age": 18 } }
returnKey	Boolean	Returns only index keys in result documents.	{ "returnKey": true }
showRecordId	Boolean	Includes the internal storage engine record ID.	{ "showRecordId": true }