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Filter by Field Presence
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To query for documents that contain a particular field,
use extension methodWhereExists()which is accessible from DocumentQuery. -
A document that doesn't contain the specified field will be excluded from the query results.
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In this page:
Filter by field name
// 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
// 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 |
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