Entity Property Reference

This API is supported for first-generation runtimes and can be used when upgrading to corresponding second-generation runtimes. If you are updating to the App Engine Go 1.12+ runtime, refer to the migration guide to learn about your migration options for legacy bundled services.

Firestore in Datastore mode (Datastore) supports a variety of data types for property values. These include, among others:

• Integers
• Floating-point numbers
• Strings
• Dates
• Binary data

For a full list of types, see Properties and value types.

Properties and value types

The data values associated with an entity consist of one or more properties. Each property has a name and one or more values. A property can have values of more than one type, and two entities can have values of different types for the same property. Properties can be indexed or unindexed (queries that order or filter on a property P will ignore entities where P is unindexed). An entity can have at most 20,000 indexed properties.

Note: Properties with multiple values can be useful, for instance, when performing queries with equality filters: an entity satisfies the query if any of its values for a property matches the value specified in the filter. For more details on multiple-valued properties, including issues you should be aware of, see the Datastore Queries page.

The following value types are supported:

Value type	Go type(s)	Sort order	Notes
Integer	int int8 int16 int32 int64	Numeric	64-bit integer, signed
Floating-point number	float32 float64	Numeric	64-bit double precision, IEEE 754
Boolean	bool	false<true
String (short)	string	Unicode	Up to 1500 bytes
String (long)	string (with noindex)	None	Up to 1 megabyte Not indexed
Byte slice (short)	datastore.ByteString	Byte order	Up to 1500 bytes
Byte slice (long)	[]byte	None	Up to 1 megabyte Not indexed
Date and time	time.Time	Chronological
Geographical point	appengine.GeoPoint	By latitude, then longitude
Datastore key	*datastore.Key	By path elements (kind, identifier, kind, identifier...)
Blobstore key	appengine.BlobKey	Byte order

You can also use a struct or slice to aggregate properties. See the Datastore reference for more details.

When a query involves a property with values of mixed types, Datastore uses a deterministic ordering based on the internal representations:

1. Null values
2. Fixed-point numbers
   • Integers
   • Dates and times
3. Boolean values
4. Byte sequences
   • Byte slices (short)
   • Unicode string
   • Blobstore keys
5. Floating-point numbers
6. Geographical points
7. Datastore keys

Because long byte slices and long strings are not indexed, they have no ordering defined.

Note: Integers and floating-point numbers are considered separate types in Datastore. If an entity uses a mix of integers and floats for the same property, all integers will be sorted before all floats: for example,

7 < 3.2