Cloud Datastore API - php - GqlQuery - Binding args - google-app-engine

Question

I'm trying to bind some arguments to my GQL query string.
Everything's fine when I run the query without binding anything:
$result = $DB->query_entities("SELECT * FROM kind WHERE fieldName = 4
LIMIT 1");
But I don't know how to bind some arguments. This is how I'm trying to do so:
function query_entities($query_string, $args=[]){
$gql_query = new Google_Service_Datastore_GqlQuery();
$gql_query->setQueryString($query_string);
$gql_query->setAllowLiteral(true);
if( !empty($args) ){
$binding_args = [];
foreach ($args as $key => $value) {
$binding_value = new Google_Service_Datastore_Value();
$binding_value->setIntegerValue($value);
$arg = new Google_Service_Datastore_GqlQueryArg();
$arg->setName($key);
$arg->setValue($binding_value);
$binding_args[] = $arg;
}
$gql_query->setNameArgs($binding_args);
}
$req = new Google_Service_Datastore_RunQueryRequest();
$req->setGqlQuery($gql_query);
return $this->dataset->runQuery($this->dataset_id, $req, []);
}
$exampleValue = 4;
$result = $DB->query_entities("SELECT * FROM kind WHERE fieldName = :fieldName LIMIT 1", ["fieldName" => $exampleValue]);
Or:
function query_entities($query_string, $args=[]){
$gql_query = new Google_Service_Datastore_GqlQuery();
$gql_query->setQueryString($query_string);
$gql_query->setAllowLiteral(true);
if( !empty($args) ){
$binding_args = [];
foreach ($args as $value) {
$binding_value = new Google_Service_Datastore_Value();
$binding_value->setIntegerValue($value);
$arg = new Google_Service_Datastore_GqlQueryArg();
$arg->setValue($binding_value);
$binding_args[] = $arg;
}
$gql_query->setNumberArgs($binding_args);
}
$req = new Google_Service_Datastore_RunQueryRequest();
$req->setGqlQuery($gql_query);
return $this->dataset->runQuery($this->dataset_id, $req, []);
}
$exampleValue = 4;
$result = $DB->query_entities("SELECT * FROM kind WHERE fieldName = :1 LIMIT 1", [$exampleValue]);
This is what I get:
'Error calling POST https://www.googleapis.com/datastore/v1beta2/datasets/age-of-deployment/runQuery: (400) Lexical error at line 1, column 52. Encountered: ":" (58), after : ""' in ...

Answer 1

Cloud Datastore GQL and Python GQL (App Engine) handle argument binding slightly differently.
In this case, you need to use a # instead of a :, for instance:
SELECT * FROM kind WHERE fieldName = #fieldName LIMIT 1
or
SELECT * FROM kind WHERE fieldName = #1 LIMIT 1
Here's the reference documentation for argument binding in Cloud Datastore GQL.