A value that is populated in Codable objects with theDocumentReferenceof the current document by the Firestore.Decoder when a document is read.

If the field name used for this type conflicts with a read document field,an error is thrown. For example, if a custom object has a fieldfirstNameannotated with@DocumentID, and there is a property from the documentnamedfirstName as well, an error is thrown when you try to read thedocument.

When writing a Codable object containing an@DocumentID annotated field,its value is ignored. This allows you to read a document from one path andwrite it into another without adjusting the value here.

NOTE: Trying to encode/decode this type using encoders/decoders other thanFirestore.Encoder leads to an error.

Declaration

@propertyWrapperpublicstructDocumentID<Value:DocumentIDWrappable&Codable>:DocumentIDProtocol,Codable

extensionDocumentID:EquatablewhereValue:Equatable

extensionDocumentID:HashablewhereValue:Hashable

Wraps anOptional field in aCodable object such that when the fieldhas anil value it will encode to a null value in Firestore. Normally,optional fields are omitted from the encoded document.

This is useful for ensuring a field is present in a Firestore document,even when there is no associated value.

Declaration

@propertyWrapperpublicstructExplicitNull<Value>

extensionExplicitNull:EquatablewhereValue:Equatable

extensionExplicitNull:HashablewhereValue:Hashable

extensionExplicitNull:EncodablewhereValue:Encodable

extensionExplicitNull:DecodablewhereValue:Decodable

A property wrapper that marks anOptional<Timestamp> field to bepopulated with a server timestamp. If aCodable object being writtencontains anil for an@ServerTimestamp-annotated field, it will bereplaced withFieldValue.serverTimestamp() as it is sent.

Example:

structCustomModel{@ServerTimestampvarts:Timestamp?}

Then writingCustomModel(ts: nil) will tell server to fillts withcurrent timestamp.

Declaration

@propertyWrapperpublicstructServerTimestamp<Value>:CodablewhereValue:ServerTimestampWrappable&Codable

extensionServerTimestamp:EquatablewhereValue:Equatable

extensionServerTimestamp:HashablewhereValue:Hashable

A property wrapper that listens to a Firestore collection.

In the following example,FirestoreQuery will fetch all documents from thefruits collection, filtering only documents whoseisFavourite attributeis equal totrue, map members of result set to theFruit type, and makethem available via the wrapped valuefruits.

structContentView:View{@FirestoreQuery(collectionPath:"fruits",predicates:[.whereField("isFavourite",isEqualTo:true)])varfruits:[Fruit]varbody:someView{List(fruits){fruitinText(fruit.name)}}}

FirestoreQuery also supports returning aResult type. The.success casereturns an array of elements, whereas the.failure case returns an errorin case mapping the Firestore docments wasn’t successful:

structContentView:View{@FirestoreQuery(collectionPath:"fruits",predicates:[.whereField("isFavourite",isEqualTo:true)])varfruitResults:Result<[Fruit],Error>varbody:someView{ifcaselet.success(fruits)=fruitResults{List(fruits){fruitinText(fruit.name)}}elseifcaselet.failure(error)=fruitResults{Text("Couldn't map data:\(error.localizedDescription)")}}

Alternatively, theprojected value of the property wrapper provides access totheerror as well. This allows you to display a list of all successfully mappeddocuments, as well as an error message with details about the documents that couldn’tbe mapped successfully (e.g. because of a field name mismatch).

structContentView:View{@FirestoreQuery(collectionPath:"mappingFailure",decodingFailureStrategy:.ignore)privatevarfruits:[Fruit]varbody:someView{VStack(alignment:.leading){List(fruits){fruitinText(fruit.name)}if$fruits.error!=nil{HStack{Text("There was an error").foregroundColor(Color(UIColor.systemBackground))Spacer()}.padding(30).background(Color.red)}}}}

Internally,@FirestoreQuery sets up a snapshot listener and publishesany incoming changes via an@StateObject.

The projected value of this property wrapper provides access to aconfiguration object of typeFirestoreQueryConfiguration which can be usedto modify the query criteria. Changing the filter predicates results in theunderlying snapshot listener being unregistered and a new one registered.

Button("Show only Apples and Oranges"){$fruits.predicates=[.whereField("name",isIn:["Apple","Orange]]}

This property wrapper does not support updating thewrappedValue, i.e.you need to use Firestore’s other APIs to add, delete, or modify documents.

Declaration

@available(iOS14.0,macOS11.0,tvOS14.0,watchOS7.0,*)@propertyWrapperpublicstructFirestoreQuery<T>:DynamicProperty