compound

must and mustNot Example

The following example uses a combination of must and mustNot clauses to contruct a query. The must clause uses the text operator to search for the term varieties in the description field. For a document to match, it must fulfill the must clause. The mustNot clause performs a search operation for the term apples in the description field. For a document to match, it must not fulfill the mustNot clause.

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db.fruit.aggregate([
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  {
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    $search: {
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      "compound": {
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        "must": [{
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          "text": {
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            "query": "varieties",
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            "path": "description"
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          }
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        }],
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        "mustNot": [{
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          "text": {
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            "query": "apples",
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            "path": "description"
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          }
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        }]
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      }
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    }
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  }
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])

The above query returns the document with _id: 3 because its description field contains the word varieties and does not contain apples.

must and should Example

The following query uses must to specify search conditions which must be met and should to specify preference for documents containing the word Fuji. The $project pipeline stage excludes all document fields except _id and adds a score field, which displays the document's relevance score.

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db.fruit.aggregate([
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  {
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    $search: {
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      "compound": {
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        "must": [{
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          "text": {
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            "query": "varieties",
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            "path": "description"
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          }
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        }],
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        "should": [{
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          "text": {
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            "query": "Fuji",
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            "path": "description"
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          }
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        }]
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      }
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    }
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  },
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  {
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    $project: {
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      "score": { "$meta": "searchScore" }
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    }
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  }
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])

The above query returns the following results:

{ "_id" : 1, "score" : 0.6425117254257202 }
{ "_id" : 3, "score" : 0.21649497747421265 }

The document with _id: 1 has a higher score because its description field contains the word Fuji, satisfying the should clause.

minimumShouldMatch Example

In a query with multiple should clauses, you can use the miniumumShouldMatch option to specify a minimum number of clauses which must match to return a result.

The following query has one must clause and two should clauses, with a minimumShouldMatch value of 1. A document must include the term varieties in the description field and must include either Fuji or Golden Delicious in the description field to be included in the result set.

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db.fruit.aggregate([
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  {
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    $search: {
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      "compound": {
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        "must": [{
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          "text": {
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             "query": "varieties",
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             "path": "description"
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          }
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        }],
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        "should": [
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          {
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            "text": {
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              "query": "Fuji",
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              "path": "description"
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            }
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          },
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          {
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            "text": {
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              "query": "Golden Delicious",
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              "path": "description"
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            }
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          }],
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          "minimumShouldMatch": 1
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        }
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      }
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    }
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])

The above query returns the following result:

{
  "_id" : 1,
  "type" : "apple",
  "description" : "Apples come in several varieties, including Fuji, Granny Smith, and Honeycrisp.",
  "category" : "nonorganic",
  "in_stock" : false
}

The document with _id: 1 matches the must clause and the first of the two should clauses.

filter Examples

filter behaves the same as must, except that the filter clause is not considered in a returned document's score, and therefore does not affect the order of the returned documents.

Nested Example

The following example uses nested compound clauses to construct a query. For this example, the fruit collection has an index on the type, category, and in_stock fields, whose text fields use the default analyzer. The query requires documents to only satisfy one of the following should clauses:

• Contain the word apple in the type field.
• Contain the term organic in the category field and have the value true in the in_stock field.

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db.fruit.aggregate([
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  {
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    $search: {
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      "compound": {
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        "should": [
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          {
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            "text": {
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              "query": "apple",
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              "path": "type"
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            }
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          },
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          {
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            "compound": {
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              "must": [
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                {
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                  "text": {
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                    "query": "organic",
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                    "path": "category"
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                  }
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                },
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                {
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                  "equals": {
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                    "value": true,
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                    "path": "in_stock"
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                  }
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                }
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              ]
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            }
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          }
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        ],
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        "minimumShouldMatch": 1
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      }
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    }
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  }
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])

The above query returns the following result:

{
  "_id" : 3,
  "type" : "pear",
  "description" : "Bosc and Bartlett are the most common varieties of pears.",
  "category" : "organic",
  "in_stock" : true
}
{
  "_id" : 1,
  "type" : "apple",
  "description" : "Apples come in several varieties, including Fuji, Granny Smith, and Honeycrisp.",
  "category" : "nonorganic",
  "in_stock" : false
}

The above document fulfills all the requirements for inclusion:

• The document with _id: 3 matches the must clause nested within the second should clause.
• The document with _id: 1 matches the first should clause.