how-to-filter-by-field.dotnet.markdown

Filter by Field Presence

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{NOTE: }

• To query for documents that contain a particular field,
  use extension method WhereExists() which is accessible from DocumentQuery.

• A document that doesn't contain the specified field will be excluded from the query results.

• In this page:

  • Filter by field name
  • Filter by field path
  • Syntax

{NOTE/}

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{PANEL: Filter by field name }

{CODE-TABS} {CODE-TAB:csharp:Sync whereExists_1@ClientApi\Session\Querying\HowToFilterByField.cs /} {CODE-TAB:csharp:Async whereExists_1_async@ClientApi\Session\Querying\HowToFilterByField.cs /} {CODE-TAB-BLOCK:sql:RQL} // Only documents that contain field 'FirstName' will be returned

from Employees where exists("FirstName") {CODE-TAB-BLOCK/} {CODE-TABS/}

{PANEL/}

{PANEL: Filter by field path }

{CODE-TABS} {CODE-TAB:csharp:Sync whereExists_2@ClientApi\Session\Querying\HowToFilterByField.cs /} {CODE-TAB:csharp:Async whereExists_2_async@ClientApi\Session\Querying\HowToFilterByField.cs /} {CODE-TAB-BLOCK:sql:RQL} // Only documents that contain the 'Latitude' property in the specified path will be returned

from Employees where exists("Address.Location.Latitude") {CODE-TAB-BLOCK/} {CODE-TABS/}

{PANEL/}

{PANEL: Syntax}

{CODE whereExists_syntax@ClientApi\Session\Querying\HowToFilterByField.cs /}

Parameters	Type	Description
fieldName	string	The name / path of the document field to filter by
propertySelector	Expression<Func<T,TValue>>	Lambda expression with name / path of the document field to filter by

{PANEL/}

Related Articles

Client API

• What is a Document Query

Indexes

• Querying: Filtering
• Query vs DocumentQuery