CODEWITHSUNDEEP
javagoogle-app-enginerestgoogle-cloud-endpointsjdo
pimmen
pimmen

Reputation: 402

Querying with multiple id parameters in google app engine

I really wanted to get Objectify to work, but I just couldn't figure out why it didn't work in my project so I switched to JDO instead and have these problems. I'm doing a project management app, so since a person can be engaged in multiple projects and projects can have many people on them, I have made an unowned relationship between Person.java and Project.java

Person.java package com.pontuse.appendpoint;

import java.util.List;

import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;

@PersistenceCapable
public class Person {
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    Long id;
    @Persistent
    String userName;
    @Persistent
    String pass;
    //Modelling relationship with projects
    @Persistent
    List<Long> projectsInvolved;

    public Person() {
    }

    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPass() {
        return pass;
    }
    public void setPass(String pass) {
        this.pass = pass;
    }

    public List<Long> getProjectsInvolved() {
        return projectsInvolved;
    }

    public void setProjectsInvolved(List<Long> projectsInvolved) {
        this.projectsInvolved = projectsInvolved;
    }
}

Project.java

package com.pontuse.appendpoint;

import java.util.Date;
import java.util.List;

import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;

@PersistenceCapable
public class Project {
    @PrimaryKey
    @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
    Long id;
    @Persistent
    Long adminId;
    @Persistent
    Date deadline;

    //Modelling relationship with people
    @Persistent
    List<Long> peopleOn;
    @Persistent
    List<Long> tasksIn;
    @Persistent
    List<Long> tasksDoing;
    @Persistent
    List<Long> tasksDone;

    public Project() {
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public Long getAdminId() {
        return adminId;
    }

    public void setAdminId(Long adminId) {
        this.adminId = adminId;
    }

    public Date getDeadline() {
        return deadline;
    }

    public void setDeadline(Date deadline) {
        this.deadline = deadline;
    }

    public List<Long> getTasksIn() {
        return tasksIn;
    }

    public void setTasksIn(List<Long> tasksIn) {
        this.tasksIn = tasksIn;
    }

    public List<Long> getTasksDoing() {
        return tasksDoing;
    }

    public void setTasksDoing(List<Long> tasksDoing) {
        this.tasksDoing = tasksDoing;
    }

    public List<Long> getTasksDone() {
        return tasksDone;
    }

    public void setTasksDone(List<Long> tasksDone) {
        this.tasksDone = tasksDone;
    }

    public void setPeopleOn(List<Long> peopleOn) {
        this.peopleOn = peopleOn;
    }

    public List<Long> getPeopleOn() {
        return peopleOn;
    }
}

So, I've tried to do a query that will return all the projects a person is assigned to. This is what I have so far:

PojectEndpoint.java

@ApiMethod(name = "getPersonsProjects")
    public CollectionResponse<Project> getPersonsProjects(@Named("projects") List<Long> projects){
        PersistenceManager mgr = null;
        List<Project> execute = new ArrayList<Project>();

        for(Long l: projects)
        execute.add(mgr.getObjectById(Project.class, l));

        mgr.close();
        return CollectionResponse.<Project> builder().setItems(execute).build();
    }

So far, I've only got a 404 when I supply a list of valid project ids 

404 Not Found

- Hide headers -

Cache-Control:  no-cache, no-store, max-age=0, must-revalidate
Content-Encoding:  gzip
Content-Length:  29
Content-Type:  text/html; charset=UTF-8
Date:  Wed, 08 Oct 2014 20:38:05 GMT
Expires:  Fri, 01 Jan 1990 00:00:00 GMT
Pragma:  no-cache
Server:  GSE

Not Found

and if I just enter one (still valid) id I get a NullPointerException

503 Service Unavailable

- Show headers -

{
"error": {
"errors": [
{
"domain": "global",
"reason": "backendError",
"message": "java.lang.NullPointerException"
}
],
"code": 503,
"message": "java.lang.NullPointerException"
}
}

Can somebody see what's going on or if I've implemented the method all wrong?

Upvotes: 1

Views: 510

Answers (1)

Price
Price

Reputation: 2703

It seems like you have already got rid of the NullPointerException using Peter's suggestion. To solve the problem of the 404 Not Found Exception, you would have to add the @Nullable annotation before the @Named annotation of your projects parameter of the API method getPersonsProjects. This will tell App Engine to treat this parameter as a query parameter that does not need a URL path.

Source: https://cloud.google.com/appengine/docs/java/endpoints/paramreturn_types#query_parameters

Upvotes: 1

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