I have a simple question:
In GQL syntax summary
<condition> := <property> {< | <= | > | >= | = | != } <value>
but in an example here
if users.get_current_user():
user_pets = db.GqlQuery("SELECT * FROM Pet WHERE owner = :1",
users.get_current_user())
What is :1 ?
According to syntax there should be := there.
Thanks.
The GQL grammar on the syntax link you posted is this:
SELECT [* | __key__] FROM <kind>
[WHERE <condition> [AND <condition> ...]]
[ORDER BY <property> [ASC | DESC] [, <property> [ASC | DESC] ...]]
[LIMIT [<offset>,]<count>]
[OFFSET <offset>]
<condition> := <property> {< | <= | > | >= | = | != } <value>
<condition> := <property> IN <list>
<condition> := ANCESTOR IS <entity or key>
The := in the last three lines means that <condition> in the main expression can be replaced with the expression to the right of the := in any of the three <condition> statements.
In the example, they have chosen to select * instead of __key__, the <kind> is Pet, there is only one WHERE condition, and there are no ORDER BY, LIMIT or OFFSET clauses.
So the main expression simplifies to:
SELECT * FROM Pet WHERE <condition>
We can then substitute the first condition expression, ie:
<condition> := <property> {< | <= | > | >= | = | != } <value>
Resulting in:
SELECT * FROM Pet WHERE <property> {< | <= | > | >= | = | != } <value>
In the example, <property> is owner, the operator is =, and the <value> is :1, ie:
SELECT * FROM Pet WHERE owner = :1
According to the documentation for the GqlQuery class, the :1 means that the value will be bound to the first argument to GqlQuery() (after the query). So in the example, the value is users.get_current_user().
Update:
I don't think either of those would work, because they are both missing a double quote to end the string of the query. However, both of the following should work:
query = db.GqlQuery(
"SELECT * FROM Rep WHERE author = :1",
users.get_current_user())
user = users.get_current_user()
query = db.GqlQuery(
"SELECT * FROM Rep WHERE author = :1",
user)
Once you have the query object you can call fetch() on it to get the items as a list. Or, you can also iterate directly over the query.