$strcasecmp (expression operator)

Definition

$strcasecmp

Performs case-insensitive comparison of two strings. Returns

• 1 if first string is "greater than" the second string.
• 0 if the two strings are equal.
• -1 if the first string is "less than" the second string.

$strcasecmp has the following syntax:

{ $strcasecmp: [ <expression1>, <expression2> ] }

The arguments can be any valid expression as long as they resolve to strings. For more information on expressions, see Expressions.

Behavior

$strcasecmp only has a well-defined behavior for strings of ASCII characters.

For a case sensitive comparison, see $cmp.

Example

Consider a inventory collection with the following documents:

db.inventory.insertMany( [
   { _id: 1, item: "ABC1", quarter: "13Q1", description: "product 1" },
   { _id: 2, item: "ABC2", quarter: "13Q4", description: "product 2" },
   { _id: 3, item: "XYZ1", quarter: "14Q2", description: null }
] )

The following operation uses the $strcasecmp operator to perform case-insensitive comparison of the quarter field value to the string "13q4":

db.inventory.aggregate(
   [
     {
       $project:
          {
            item: 1,
            comparisonResult: { $strcasecmp: [ "$quarter", "13q4" ] }
          }
      }
   ]
)

The operation returns the following results:

{ _id: 1, item: "ABC1", comparisonResult: -1 }
{ _id: 2, item: "ABC2", comparisonResult: 0 }
{ _id: 3, item: "XYZ1", comparisonResult: 1 }