> For the complete documentation index, see [llms.txt](https://book.tml.ink/app-development/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.tml.ink/app-development/backend-solution/queryselectors.md).

# queryselectors

## Comparison Operators

| Name |                             Description                             |
| :--: | :-----------------------------------------------------------------: |
|  $eq |         Matches values that are equal to a specified value.         |
|  $gt |       Matches values that are greater than a specified value.       |
| $gte | Matches values that are greater than or equal to a specified value. |
|  $in |           Matches any of the values specified in an array.          |
|  $lt |         Matches values that are less than a specified value.        |
| $lte |   Matches values that are less than or equal to a specified value.  |
|  $ne |     Matches all values that are not equal to a specified value.     |
| $nin |          Matches none of the values specified in an array.          |

## Logical

| Name |                                               Description                                               |
| :--: | :-----------------------------------------------------------------------------------------------------: |
| $and | Joins query clauses with a logical AND returns all documents that match the conditions of both clauses. |
| $not |  Inverts the effect of a query expression and returns documents that do not match the query expression. |
| $nor |      Joins query clauses with a logical NOR returns all documents that fail to match both clauses.      |
|  $or | Joins query clauses with a logical OR returns all documents that match the conditions of either clause. |

## Element

|   Name  |                       Description                      |
| :-----: | :----------------------------------------------------: |
| $exists |    Matches documents that have the specified field.    |
|  $type  | Selects documents if a field is of the specified type. |

## Evaluation

|     Name    |                                             Description                                            |
| :---------: | :------------------------------------------------------------------------------------------------: |
|    $expr    |                  Allows use of aggregation expressions within the query language.                  |
| $jsonSchema |                          Validate documents against the given JSON Schema.                         |
|     $mod    | Performs a modulo operation on the value of a field and selects documents with a specified result. |
|    $regex   |                Selects documents where values match a specified regular expression.                |
|    $text    |                                        Performs text search.                                       |
|    $where   |                       Matches documents that satisfy a JavaScript expression.                      |

## Geospatial

|      Name      |                                                                  Description                                                                  |
| :------------: | :-------------------------------------------------------------------------------------------------------------------------------------------: |
| $geoIntersects |                     Selects geometries that intersect with a GeoJSON geometry. The 2dsphere index supports $geoIntersects.                    |
|   $geoWithin   |                     Selects geometries within a bounding GeoJSON geometry. The 2dsphere and 2d indexes support $geoWithin.                    |
|      $near     |          Returns geospatial objects in proximity to a point. Requires a geospatial index. The 2dsphere and 2d indexes support $near.          |
|   $nearSphere  | Returns geospatial objects in proximity to a point on a sphere. Requires a geospatial index. The 2dsphere and 2d indexes support $nearSphere. |

## Array

|    Name    |                                            Description                                           |
| :--------: | :----------------------------------------------------------------------------------------------: |
|    $all    |                 Matches arrays that contain all elements specified in the query.                 |
| $elemMatch | Selects documents if element in the array field matches all the specified $elemMatch conditions. |
|    $max    |                     Selects documents if the array field is a specified size.                    |

## Bitwise

|      Name     |                                           Description                                           |
| :-----------: | :---------------------------------------------------------------------------------------------: |
| $bitsAllClear |     Matches numeric or binary values in which a set of bit positions all have a value of 0.     |
|  $bitsAllSet  |     Matches numeric or binary values in which a set of bit positions all have a value of 1.     |
| $bitsAnyClear | Matches numeric or binary values in which any bit from a set of bit positions has a value of 0. |
|  $bitsAnySet  | Matches numeric or binary values in which any bit from a set of bit positions has a value of 1. |

## Comments

|   Name   |              Description             |
| :------: | :----------------------------------: |
| $comment | Adds a comment to a query predicate. |

## Projection Operators

|    Name    |                                       Description                                       |
| :--------: | :-------------------------------------------------------------------------------------: |
|      $     |         Projects the first element in an array that matches the query condition.        |
| $elemMatch | Projects the first element in an array that matches the specified $elemMatch condition. |
|    $meta   |              Projects the document’s score assigned during $text operation.             |
|   $slice   |  Limits the number of elements projected from an array. Supports skip and limit slices. |