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DOCS-14662 mod match expression values (#6017) #6018

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52 changes: 33 additions & 19 deletions source/reference/operator/query/mod.txt
Original file line number Diff line number Diff line change
Expand Up @@ -21,23 +21,36 @@ $mod

{ field: { $mod: [ divisor, remainder ] } }

The :query:`$mod` operator errors when passed an array with fewer
or more than two elements. See :ref:`mod-not-enough-elements` and
:ref:`mod-too-many-elements` for details.
Behavior
--------

The :query:`$mod` operator returns an error if the:

- ``[ divisor, remainder ]`` array contains fewer or more than
two elements. For examples, see :ref:`mod-not-enough-elements` and
:ref:`mod-too-many-elements` respectively.

- ``divisor`` or ``remainder`` values evaluate to:

- ``NaN`` (not a number) or ``Infinity``.

- A value that cannot be represented using a 64-bit integer.

Examples
--------

Use ``$mod`` to Select Documents
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Consider a collection ``inventory`` with the following documents:
Create an ``inventory`` collection:

.. code-block:: javascript

{ "_id" : 1, "item" : "abc123", "qty" : 0 }
{ "_id" : 2, "item" : "xyz123", "qty" : 5 }
{ "_id" : 3, "item" : "ijk123", "qty" : 12 }
db.inventory.insertMany( [
{ "_id" : 1, "item" : "abc123", "qty" : 0 },
{ "_id" : 2, "item" : "xyz123", "qty" : 5 },
{ "_id" : 3, "item" : "ijk123", "qty" : 12 }
] )

Then, the following query selects those documents in the
``inventory`` collection where value of the ``qty`` field modulo
Expand All @@ -50,6 +63,7 @@ Then, the following query selects those documents in the
The query returns the following documents:

.. code-block:: javascript
:copyable: false

{ "_id" : 1, "item" : "abc123", "qty" : 0 }
{ "_id" : 3, "item" : "ijk123", "qty" : 12 }
Expand All @@ -75,11 +89,9 @@ an array that contains a single element:
The statement results in the following error:

.. code-block:: javascript
:copyable: false

error: {
"$err" : "bad query: BadValue malformed mod, not enough elements",
"code" : 16810
}
MongoServerError: malformed mod, not enough elements

Empty Array
```````````
Expand All @@ -94,11 +106,9 @@ an empty array:
The statement results in the following error:

.. code-block:: javascript
:copyable: false

error: {
"$err" : "bad query: BadValue malformed mod, not enough elements",
"code" : 16810
}
MongoServerError: malformed mod, not enough elements

.. _mod-too-many-elements:

Expand All @@ -113,10 +123,14 @@ operator with an array that contains four elements:

.. code-block:: javascript

error: {
"$err" : "bad query: BadValue malformed mod, too many elements",
"code" : 16810
}
db.inventory.find( { qty: { $mod: [ 4, 1, 2, 3 ] } } )

The statement results in the following error:

.. code-block:: javascript
:copyable: false

MongoServerError: malformed mod, too many elements

Floating Point Arguments
~~~~~~~~~~~~~~~~~~~~~~~~
Expand Down