Filter by Field Presence

• 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

Filter by field name

• Sync
• Async
• RQL

// Only documents that contain field 'FirstName' will be returned

List<Employee> results = session
  .Advanced
  .DocumentQuery<Employee>()
  .WhereExists("FirstName")
   // Or use lambda expression: .WhereExists(x => x.FirstName)
  .ToList();

// Only documents that contain field 'FirstName' will be returned

List<Employee> results = await asyncSession
  .Advanced
  .AsyncDocumentQuery<Employee>()
  .WhereExists("FirstName")
   // Or use lambda expression: .WhereExists(x => x.FirstName)
  .ToListAsync();

// Only documents that contain field 'FirstName' will be returned

from Employees
where exists("FirstName")

Filter by field path

• Sync
• Async
• RQL

// Only documents that contain the 'Latitude' property in the specified path will be returned

List<Employee> results = session
  .Advanced
  .DocumentQuery<Employee>()
  .WhereExists("Address.Location.Latitude")
   // Or use lambda expression: .WhereExists(x => x.Address.Location.Latitude)
  .ToList();

// Only documents that contain the 'Latitude' property in the specified path will be returned

List<Employee> results = await asyncSession
  .Advanced
  .AsyncDocumentQuery<Employee>()
  .WhereExists("Address.Location.Latitude")
   // Or use lambda expression: .WhereExists(x => x.Address.Location.Latitude)
  .ToListAsync();

// Only documents that contain the 'Latitude' property in the specified path will be returned

from Employees
where exists("Address.Location.Latitude")

Syntax

IDocumentQuery<T> WhereExists(string fieldName);

IDocumentQuery<T> WhereExists<TValue>(Expression<Func<T, TValue>> propertySelector);

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