Connect by using functions.
Explore further
For detailed documentation that includes this code sample, see the following:
- Create a Cloud Run function that returns Spanner results
- Using Spanner with Cloud Run functions (1st gen)
Code sample
Go
To learn how to install and use the client library for Spanner, see Spanner client libraries .
To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .
// Package spanner contains an example of using Spanner from a Cloud Function.
package
spanner
import
(
"context"
"fmt"
"log"
"net/http"
"sync"
"cloud.google.com/go/spanner"
"github.com/GoogleCloudPlatform/functions-framework-go/functions"
"google.golang.org/api/iterator"
)
// client is a global Spanner client, to avoid initializing a new client for
// every request.
var
client
*
spanner
.
Client
var
clientOnce
sync
.
Once
// db is the name of the database to query.
var
db
=
"projects/my-project/instances/my-instance/databases/example-db"
func
init
()
{
functions
.
HTTP
(
"HelloSpanner"
,
HelloSpanner
)
}
// HelloSpanner is an example of querying Spanner from a Cloud Function.
func
HelloSpanner
(
w
http
.
ResponseWriter
,
r
*
http
.
Request
)
{
clientOnce
.
Do
(
func
()
{
// Declare a separate err variable to avoid shadowing client.
var
err
error
client
,
err
=
spanner
.
NewClient
(
context
.
Background
(),
db
)
if
err
!=
nil
{
http
.
Error
(
w
,
"Error initializing database"
,
http
.
StatusInternalServerError
)
log
.
Printf
(
"spanner.NewClient: %v"
,
err
)
return
}
})
fmt
.
Fprintln
(
w
,
"Albums:"
)
stmt
:=
spanner
.
Statement
{
SQL
:
`SELECT SingerId, AlbumId, AlbumTitle FROM Albums`
}
iter
:=
client
.
Single
().
Query
(
r
.
Context
(),
stmt
)
defer
iter
.
Stop
()
for
{
row
,
err
:=
iter
.
Next
()
if
err
==
iterator
.
Done
{
return
}
if
err
!=
nil
{
http
.
Error
(
w
,
"Error querying database"
,
http
.
StatusInternalServerError
)
log
.
Printf
(
"iter.Next: %v"
,
err
)
return
}
var
singerID
,
albumID
int64
var
albumTitle
string
if
err
:=
row
.
Columns
(
& singerID
,
& albumID
,
& albumTitle
);
err
!=
nil
{
http
.
Error
(
w
,
"Error parsing database response"
,
http
.
StatusInternalServerError
)
log
.
Printf
(
"row.Columns: %v"
,
err
)
return
}
fmt
.
Fprintf
(
w
,
"%d %d %s\n"
,
singerID
,
albumID
,
albumTitle
)
}
}
Java
To learn how to install and use the client library for Spanner, see Spanner client libraries .
To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .
import
com.google.api.client.http. HttpStatusCodes
;
import
com.google.cloud.functions.HttpFunction
;
import
com.google.cloud.functions. HttpRequest
;
import
com.google.cloud.functions. HttpResponse
;
import
com.google.cloud.spanner. DatabaseClient
;
import
com.google.cloud.spanner. DatabaseId
;
import
com.google.cloud.spanner. LazySpannerInitializer
;
import
com.google.cloud.spanner. ResultSet
;
import
com.google.cloud.spanner. SpannerException
;
import
com.google.cloud.spanner. SpannerOptions
;
import
com.google.cloud.spanner. Statement
;
import
com.google.common.annotations.VisibleForTesting
;
import
com.google.common.base.MoreObjects
;
import
java.io.PrintWriter
;
import
java.util.logging.Level
;
import
java.util.logging.Logger
;
// HelloSpanner is an example of querying Spanner from a Cloud Function.
public
class
HelloSpanner
implements
HttpFunction
{
private
static
final
Logger
logger
=
Logger
.
getLogger
(
HelloSpanner
.
class
.
getName
());
// TODO<developer>: Set these environment variables.
private
static
final
String
SPANNER_INSTANCE_ID
=
MoreObjects
.
firstNonNull
(
System
.
getenv
(
"SPANNER_INSTANCE"
),
"my-instance"
);
private
static
final
String
SPANNER_DATABASE_ID
=
MoreObjects
.
firstNonNull
(
System
.
getenv
(
"SPANNER_DATABASE"
),
"example-db"
);
private
static
final
DatabaseId
databaseId
=
DatabaseId
.
of
(
SpannerOptions
.
getDefaultProjectId
(),
SPANNER_INSTANCE_ID
,
SPANNER_DATABASE_ID
);
// The LazySpannerInitializer instance is shared across all instances of the HelloSpanner class.
// It will create a Spanner instance the first time one is requested, and continue to return that
// instance for all subsequent requests.
private
static
final
LazySpannerInitializer
SPANNER_INITIALIZER
=
new
LazySpannerInitializer
();
@VisibleForTesting
DatabaseClient
getClient
()
throws
Throwable
{
return
SPANNER_INITIALIZER
.
get
().
getDatabaseClient
(
databaseId
);
}
@Override
public
void
service
(
HttpRequest
request
,
HttpResponse
response
)
throws
Exception
{
var
writer
=
new
PrintWriter
(
response
.
getWriter
());
try
{
DatabaseClient
client
=
getClient
();
try
(
ResultSet
rs
=
client
.
singleUse
()
.
executeQuery
(
Statement
.
of
(
"SELECT SingerId, AlbumId, AlbumTitle FROM Albums"
)))
{
writer
.
printf
(
"Albums:%n"
);
while
(
rs
.
next
())
{
writer
.
printf
(
"%d %d %s%n"
,
rs
.
getLong
(
"SingerId"
),
rs
.
getLong
(
"AlbumId"
),
rs
.
getString
(
"AlbumTitle"
));
}
}
catch
(
SpannerException
e
)
{
writer
.
printf
(
"Error querying database: %s%n"
,
e
.
getMessage
());
response
.
setStatusCode
(
HttpStatusCodes
.
STATUS_CODE_SERVER_ERROR
,
e
.
getMessage
());
}
}
catch
(
Throwable
t
)
{
logger
.
log
(
Level
.
SEVERE
,
"Spanner example failed"
,
t
);
writer
.
printf
(
"Error setting up Spanner: %s%n"
,
t
.
getMessage
());
response
.
setStatusCode
(
HttpStatusCodes
.
STATUS_CODE_SERVER_ERROR
,
t
.
getMessage
());
}
}
}
Node.js
To learn how to install and use the client library for Spanner, see Spanner client libraries .
To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .
// Imports the Google Cloud client library
const
{
Spanner
}
=
require
(
' @google-cloud/spanner
'
);
// Imports the functions framework to register your HTTP function
const
functions
=
require
(
'@google-cloud/functions-framework'
);
// Instantiates a client
const
spanner
=
new
Spanner
();
// Your Cloud Spanner instance ID
const
instanceId
=
'test-instance'
;
// Your Cloud Spanner database ID
const
databaseId
=
'example-db'
;
/**
* HTTP Cloud Function.
*
* @param {Object} req Cloud Function request context.
* @param {Object} res Cloud Function response context.
*/
functions
.
http
(
'spannerQuickstart'
,
async
(
req
,
res
)
=
>
{
// Gets a reference to a Cloud Spanner instance and database
const
instance
=
spanner
.
instance
(
instanceId
);
const
database
=
instance
.
database
(
databaseId
);
// The query to execute
const
query
=
{
sql
:
'SELECT * FROM Albums'
,
};
// Execute the query
try
{
const
results
=
await
database
.
run
(
query
);
const
rows
=
results
[
0
].
map
(
row
=
>
row
.
toJSON
());
rows
.
forEach
(
row
=
>
{
res
.
write
(
`SingerId:
${
row
.
SingerId
}
, `
+
`AlbumId:
${
row
.
AlbumId
}
, `
+
`AlbumTitle:
${
row
.
AlbumTitle
}
\n`
);
});
res
.
status
(
200
).
end
();
}
catch
(
err
)
{
res
.
status
(
500
).
send
(
`Error querying Spanner:
${
err
}
`
);
}
});
Python
To learn how to install and use the client library for Spanner, see Spanner client libraries .
To authenticate to Spanner, set up Application Default Credentials. For more information, see Set up authentication for a local development environment .
import
functions_framework
from
google.cloud
import
spanner
instance_id
=
"test-instance"
database_id
=
"example-db"
client
=
spanner
.
Client
()
instance
=
client
.
instance
(
instance_id
)
database
=
instance
.
database
(
database_id
)
@functions_framework
.
http
def
spanner_read_data
(
request
):
query
=
"SELECT * FROM Albums"
outputs
=
[]
with
database
.
snapshot
()
as
snapshot
:
results
=
snapshot
.
execute_sql
(
query
)
for
row
in
results
:
output
=
"SingerId:
{}
, AlbumId:
{}
, AlbumTitle:
{}
"
.
format
(
*
row
)
outputs
.
append
(
output
)
return
"
\n
"
.
join
(
outputs
)
What's next
To search and filter code samples for other Google Cloud products, see the Google Cloud sample browser .
