Class Projection
java.lang.Object
com.datastax.astra.client.core.query.Projection
Encode the presence of a field in the result.
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Constructor Summary
ConstructorsConstructorDescriptionProjection
(String field, boolean present) Default constructor.Projection
(String field, Boolean present, Integer sliceStart, Integer sliceEnd) Default constructor. -
Method Summary
Modifier and TypeMethodDescriptionstatic Projection[]
Exclude a field in the result.static Projection[]
Include a field in the result.static Projection
Specifies the number of elements in an array to return in the query result.
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Constructor Details
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Projection
Default constructor.- Parameters:
field
- field valuepresent
- tell if field is present
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Projection
Default constructor.- Parameters:
field
- field valuepresent
- tell if field is presentsliceStart
- start of slice (mutually exclusive with 'present')sliceEnd
- end of slice (mutually exclusive with 'present'), optional
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Method Details
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include
Include a field in the result.- Parameters:
field
- include field- Returns:
- name to include
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slice
Specifies the number of elements in an array to return in the query result.// Return the first two elements { $slice: 2 } // Return the last two elements { $slice: -2 } // Skip 4 elements (from 0th index), return the next 2 { $slice: [4, 2] } // Skip backward 4 elements, return next 2 elements (forward) { $slice: [-4, 2] }
- Parameters:
field
- field name for slicestart
- start index of sliceend
- end index of slice- Returns:
- a projection for the slide
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exclude
Exclude a field in the result.- Parameters:
field
- field name to exclude- Returns:
- list of projection
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