Package com.mongodb.client.model

Class Projections

  • public final class Projections
extends Object
    A factory for projections. A convenient way to use this class is to statically import all of its methods, which allows usage like: 
        collection.find().projection(fields(include("x", "y"), excludeId()))
    Since:
    3.0
    MongoDB documentation
    Projection

    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      static <TExpression>
      Bson      		 computed​(String fieldName, TExpression expression)
      Creates a projection of a field whose value is computed from the given expression.
      static Bson elemMatch​(String fieldName)
      Creates a projection that includes for the given field only the first element of an array that matches the query filter.
      static Bson elemMatch​(String fieldName, Bson filter)
      Creates a projection that includes for the given field only the first element of the array value of that field that matches the given query filter.
      static Bson exclude​(String... fieldNames)
      Creates a projection that excludes all of the given fields.
      static Bson exclude​(List<String> fieldNames)
      Creates a projection that excludes all of the given fields.
      static Bson excludeId()
      Creates a projection that excludes the _id field.
      static Bson fields​(List<? extends Bson> projections)
      Creates a projection that combines the list of projections into a single one.
      static Bson fields​(Bson... projections)
      Creates a projection that combines the list of projections into a single one.
      static Bson include​(String... fieldNames)
      Creates a projection that includes all of the given fields.
      static Bson include​(List<String> fieldNames)
      Creates a projection that includes all of the given fields.
      static Bson meta​(String fieldName, String metaFieldName)
      Creates a $meta projection to the given field name for the given meta field name.
      static Bson metaTextScore​(String fieldName)
      Creates a projection to the given field name of the textScore, for use with text queries.
      static Bson slice​(String fieldName, int limit)
      Creates a projection to the given field name of a slice of the array value of that field.
      static Bson slice​(String fieldName, int skip, int limit)
      Creates a projection to the given field name of a slice of the array value of that field.

    • Method Detail

      • computed

        public static <TExpression> Bson computed​(String fieldName,
                                          TExpression expression)
        Creates a projection of a field whose value is computed from the given expression. Projection with an expression is only supported using the $project aggregation pipeline stage.
        Type Parameters:
        TExpression - the expression type
        Parameters:
        fieldName - the field name
        expression - the expression
        Returns:
        the projection
        See Also:
        Aggregates.project(Bson)

      • include

        public static Bson include​(String... fieldNames)
        Creates a projection that includes all of the given fields.
        Parameters:
        fieldNames - the field names
        Returns:
        the projection

      • include

        public static Bson include​(List<String> fieldNames)
        Creates a projection that includes all of the given fields.
        Parameters:
        fieldNames - the field names
        Returns:
        the projection

      • exclude

        public static Bson exclude​(String... fieldNames)
        Creates a projection that excludes all of the given fields.
        Parameters:
        fieldNames - the field names
        Returns:
        the projection

      • exclude

        public static Bson exclude​(List<String> fieldNames)
        Creates a projection that excludes all of the given fields.
        Parameters:
        fieldNames - the field names
        Returns:
        the projection

      • excludeId

        public static Bson excludeId()
        Creates a projection that excludes the _id field. This suppresses the automatic inclusion of _id that is the default, even when other fields are explicitly included.
        Returns:
        the projection

      • elemMatch

        public static Bson elemMatch​(String fieldName)
        Creates a projection that includes for the given field only the first element of an array that matches the query filter. This is referred to as the positional $ operator.
        Parameters:
        fieldName - the field name whose value is the array
        Returns:
        the projection
        MongoDB documentation
        Project the first matching element ($ operator)

      • elemMatch

        public static Bson elemMatch​(String fieldName,
                             Bson filter)
        Creates a projection that includes for the given field only the first element of the array value of that field that matches the given query filter.
        Parameters:
        fieldName - the field name
        filter - the filter to apply
        Returns:
        the projection
        MongoDB documentation
        elemMatch

      • meta

        public static Bson meta​(String fieldName,
                        String metaFieldName)
        Creates a $meta projection to the given field name for the given meta field name.
        Parameters:
        fieldName - the field name
        metaFieldName - the meta field name
        Returns:
        the projection
        Since:
        4.1
        MongoDB documentation
        reference/operator/projection/meta/#projection

      • metaTextScore

        public static Bson metaTextScore​(String fieldName)
        Creates a projection to the given field name of the textScore, for use with text queries.
        Parameters:
        fieldName - the field name
        Returns:
        the projection
        MongoDB documentation
        textScore

      • slice

        public static Bson slice​(String fieldName,
                         int limit)
        Creates a projection to the given field name of a slice of the array value of that field.
        Parameters:
        fieldName - the field name
        limit - the number of elements to project.
        Returns:
        the projection
        MongoDB documentation
        Slice

      • slice

        public static Bson slice​(String fieldName,
                         int skip,
                         int limit)
        Creates a projection to the given field name of a slice of the array value of that field.
        Parameters:
        fieldName - the field name
        skip - the number of elements to skip before applying the limit
        limit - the number of elements to project
        Returns:
        the projection
        MongoDB documentation
        Slice

      • fields

        public static Bson fields​(Bson... projections)
        Creates a projection that combines the list of projections into a single one. If there are duplicate keys, the last one takes precedence.
        Parameters:
        projections - the list of projections to combine
        Returns:
        the combined projection

      • fields

        public static Bson fields​(List<? extends Bson> projections)
        Creates a projection that combines the list of projections into a single one. If there are duplicate keys, the last one takes precedence.
        Parameters:
        projections - the list of projections to combine
        Returns:
        the combined projection