I want to send a POST request with Postman that creates a Purchase object and save it in the database.
My class Purchase:
#Document(collection = "purchases")
public class Purchase {
#Id
private String id;
#DBRef
private User buyer;
#DBRef
private List<File> FilesToPurchase;
private Long timestamp;
public Purchase() { }
public Purchase(User buyer, List<File> filesToPurchase) {
this.buyer = buyer;
FilesToPurchase = filesToPurchase;
}
// Getters and setters not posted here.
I want to insert in the database a new purchase done by an already existing User "buyer" who wants to purchase a list of already exsting Files "FilesToPurchase".
I have in my controller a POST function that receives a Purchase object using the annotation #RequestBody, but so far I've got NullPointerExceptions because of the empty Purchase object received.
I don't know how to handle #DBRef annotation. In Postman I try sending a JSON like this:
{
"buyer": {
"$ref":"users",
"$id" : "ObjectId('5bb5d6634e5a7b2bea75d4a2')"
},
"FilesToPurchase": [
{ "$ref":"files",
"$id" : "ObjectId('5bb5d6634e5a7b2bea75d4a5')"
}
]
}
Rename field "FilesToPurchase" and setter to "filesToPurchase" to match java conventions and try this
{ "buyer": { "id" : "5bb5d6634e5a7b2bea75d4a2" }, "filesToPurchase": [ { "id" : "5bb5d6634e5a7b2bea75d4a5" } ] }
By marking controller parameter with #RequestBody you ask Spring to deserialize input json to java object(Jackson ObjectMapper is used by default). It will not automaticly populate the whole #Dbref field, you should do it yourself by querying mongo if you want, however the only field you need in referred object to save object that reffers it is 'id'.
Related
Hi I have implemented a mock solution to my problem and I'm pretty sure something better already exist.
Here's that I want to achieve :
I have created a point to load categories with or without subCategories
/api/categories/1?fields=subCategories
returns
{
"id":"1",
"name":"test",
"subCategories":[{
"id":"1",
"name":"test123"
}]
}
/api/categories/1
returns
{
"id":"1",
"name":"test"
}
My entities
#Entity
class Category{
#Id
private String id;
private String name;
private Set<SubCategory> subCategories;
}
#Entity
class SubCategory{
#Id
private String id;
private String name;
}
I have removed services since this is not the point.
I've created CategoryDTO and SubCategoryDTO classes with the same fields as Category and SubCategory
The converter
class CategoryDTOConverter{
CategoryDTO convert(Category category,String fields){
CategoryDTO dto=new CategoryDTO();
dto.setName(category.getName());
if(StringUtils.isNotBlank(fields) && fields.contains("subCategories"){
category.getSubCategories().forEach(s->{
dto.getSubcategories().add(SubCategoryDTOConverter.convert(s));
}
}
}
}
I used com.cosium.spring.data.jpa.entity.graph.repository to create an EntityGraph from a list of attribute path
#Repository
interface CategoryRepository extends EntityGraphJpaRepository<Category, String>{
Optional<T> findById(String id,EntityGraph entityGraph);
}
Controller
#RestController
#CrossOrigin
#RequestMapping("/categories")
public class CategoryController {
#GetMapping(value = "/{id}")
public ResponseEntity<CategoryDTO> get(#PathVariable("id") String id, #RequestParam(value="fields",required=false) String fields ) throws Exception {
Optional<Category> categOpt=repository.findById(id,fields!=null?EntityGraphUtils.fromAttributePaths(fields):null);
if(categOpt.isEmpty())
throws new NotFoundException();
return ResponseEntity.ok(categoryDTOConverter.convert(categOpt.get(),fields);
}
}
This is a simple example to illustrate what I need to do
I don't want to load fields that clients doesn't want to use
How could I do this in a better way ?
Take a look at GraphQL since it is a perfect match for your use case. With GraphQL it is the client that decides which attributes it wants to receive by providing in the POST request body exactly which attributes are needed to be included in the response. This is way more manageable than trying to handle all this on your own.
Spring Boot recently added its own Spring GraphQL library, so it is quite simple to integrate it in your Spring Boot app.
I'm setting a server to get a CRUD api from a postgresql Database using JPA. Everytime I want to expose an object from the DB it duplicate the idObject.
When I get an object from the database using springframework and send it after that, it duplicate the idObject like this:
{
"siteId": 3,
"contractId": "1",
"name": "sitenumber1",
"siteIdObject": {
"siteId": 3,
"contractId": "1"
}
}
SiteId and contractId are repeating...
but I want something like that:
{
"siteId": 3,
"contractId": "1",
"name": "sitenumber1"
}
I want to avoid using DTO because I think there is a better way but I don't find it. Since I'm using springFramework for just one or two month I'm maybe forgeting something...
there is the code:
Site code:
#Entity
#IdClass(SiteId.class)
#Table(name = "site", schema="public")
public class Site {
#Id
#Column(name="siteid")
private Integer siteId;
#Id
#Column(name="clientid")
private Integer contractId;
private String name;
#JsonIgnore
#OneToMany(cascade=CascadeType.ALL, mappedBy = "site")
public Set<Device> devices;
//setter, getter, hash, equals, tostring, constructor empty one and full one
SiteId code:
public class SiteId implements Serializable {
private Integer siteId;
private Integer contractId;
// setter, getter, constructor empty and full, hash and equals
Thanks to help :)
Bessaix Daniel
If you are using Spring you might also be using Jackson so if you annotate your SiteIdclass with #JsonIgnoreType it shouldn't be serialized at all when the Site object is serialized.
I am however unsure if this will break your application logic now that the id object is not serialized anymore.
this is one of my REST controller,
#RestController
#RequestMapping("/users/Ache")
public class Users {
#GetMapping
public User getUser() {
User user = new User();
return user;
}
}
As response, Spring boot will translate my Object to JSON,
this is response:
{
"username": "Ache",
"password": "eee",
"token": "W0wpuLAUQCwIH1r2ab85gWdJOiy2cp",
"email": null,
"birthday": null,
"createDatetime": "2019-03-15T01:39:11.000+0000",
"updateDatetime": null,
"phoneNumber": null
}
I want to remove password and token fields, How can I do?
I know two hard ways:
create a new hash map
and add some necessary fields, but it too complex
set those two fields to null
but it still leaves two null valued fields, it is too ugly.
Any better solution?
Spring leverages Jackson library for JSON marshalling by default. The easiest solution that comes to mind is making use of Jackson's #JsonIgnore but that would ignore the property on both serialization and de-serialization. So the right approach would be annotating the field with #JsonProperty(access = Access.WRITE_ONLY).
For instance, inside a hypothetical User class:
#JsonProperty(access = Access.WRITE_ONLY)
private String password;
#JsonProperty(access = Access.WRITE_ONLY)
private String token;
An alternative would be using #JsonIgnore only on the getter:
#JsonIgnore
public String getPassword() {
return this.password;
}
You can also create another class, for instance UserResponse with all the fields except password and token, and make it your return type. Of course it involves creating an object and populating it, but you leave your User class clean without Jackson annotations, and de-couples your model from your representation.
Keep the getter and setter but add the WRITE_ONLY JsonProperty. This way password validations will work when you use the entity as the request body.
#NotBlank
#JsonProperty(access = Access.WRITE_ONLY)
private String password;
I would like to know how to access a deep collection class attribute in a GET request. My endpoint maps my query strings through #ModelAttribute annotation:
Given that:
public class MyEntity
{
Set<Item> items;
Integer status;
// getters setters
}
public class Item
{
String name;
// getters setters
}
And my GET request: localhost/entities/?status=0&items[0].name=Garry
Produces bellow behavior?
#RequestMapping(path = "/entities", method = RequestMethod.GET)
public List<MyEntity> findBy(#ModelAttribute MyEntity entity) {
// entity.getItems() is empty and an error is thrown: "Property referenced in indexed property path 'items[0]' is neither an array nor a List nor a Map."
}
Should my "items" be an array, List or Map? If so, there´s alternatives to keep using as Set?
Looks like there is some problem with the Set<Item>.
If you want to use Set for the items collection you have to initialize it and add some items:
e.g. like this:
public class MyEntity {
private Integer status;
private Set<Item> items;
public MyEntity() {
this.status = 0;
this.items = new HashSet<>();
this.items.add(new Item());
this.items.add(new Item());
}
//getters setters
}
but then you will be able to set only the values of this 2 items:
This will work: http://localhost:8081/map?status=1&items[0].name=asd&items[1].name=aaa
This will not work: http://localhost:8081/map?status=1&items[0].name=asd&items[1].name=aaa&items[2].name=aaa
it will say: Invalid property 'items[2]' of bean class MyEntity.
However if you switch to List:
public class MyEntity {
private Integer status;
private List<Item> items;
}
both urls map without the need to initialize anything and for various number of items.
note that I didn't use #ModelAttribute, just set the class as paramter
#GetMapping("map")//GetMapping is just a shortcut for RequestMapping
public MyEntity map(MyEntity myEntity) {
return myEntity;
}
Offtopic
Mapping a complex object in Get request sounds like a code smell to me.
Usually Get methods are used to get/read data and the url parameters are used to specify the values that should be used to filter the data that has to be read.
if you want to insert or update some data use POST, PATCH or PUT and put the complex object that you want to insert/update in the request body as JSON(you can map that in the Spring Controller with #RequestBody).
I have been working in Spring Boot with the Spring Data MongoDB project and I am seeing behavior I am not clear on. I understand that the id field will go to _id in the Mongo repository per http://docs.spring.io/spring-data/mongodb/docs/current/reference/html/#mapping.conventions.id-field. My problem is that it also seems to be happening for child entities which does not seem correct.
For example I have these classes (leaving out setters and getters for brevity) :
public class MessageBuild {
#Id
private String id;
private String name;
private TopLevelMessage.MessageType messageType;
private TopLevelMessage message;
}
public interface TopLevelMessage {
public enum MessageType {
MapData
}
}
public class MapData implements TopLevelMessage {
private String layerType;
private Vector<Intersection> intersections;
private Vector<RoadSegment> roadSegments;
}
public class RoadSegment {
private int id;
private String name;
private Double laneWidth;
}
and I create an object graph using this I use the appropriate MongoRepository class to save I end up with an example document like this (with _class left out):
{
"_id" : ObjectId("57c0c05568a6c4941830a626"),
"_class" : "com.etranssystems.coreobjects.persistable.MessageBuild",
"name" : "TestMessage",
"messageType" : "MapData",
"message" : {
"layerType" : "IntersectionData",
"roadSegments" : [
{
"_id" : 2001,
"name" : "Road Segment 1",
"laneWidth" : 3.3
}
]
}
}
In this case a child object with a field named id has its mapping converted to _id in the MongoDB repository. Not the end of the world although not expected. The biggest problem is now that this is exposed by REST MVC the _id fields are not returned from a query. I have tried to set the exposeIdsFor in my RepositoryRestConfigurerAdapter for this class and it exposes the id for the top level document but not the child ones.
So circling around the 2 questions/issues I have are:
Why are child object fields mapped to _id? My understanding is that this should only happen on the top level since things underneath are not really documents in their own right.
Shouldn't the configuration to expose id fields work for child objects in a document if it is mapping the field names?
Am I wrong to think that RoadSegment does not contain a getId() ? From Spring's documentation:
A property or field without an annotation but named id will be mapped
to the _id field.
I believe Spring Data does this even to nested classes, when it finds an id field. You may either add a getId(), so that the field is named id or annotate it with #Field:
public class RoadSegment {
#Field("id")
private int id;
private String name;
private Double laneWidth;
}
I agree this automatic conversion of id/_id should only be done at the top level in my opinion.
However, the way Spring Data Mongo conversion is coded, all java ojects go through the exact same code to be converted into json (both top and nested objects):
public class MappingMongoConverter {
...
protected void writeInternal(Object obj, final DBObject dbo, MongoPersistentEntity<?> entity) {
...
if (!dbo.containsField("_id") && null != idProperty) {
try {
Object id = accessor.getProperty(idProperty);
dbo.put("_id", idMapper.convertId(id));
} catch (ConversionException ignored) {}
}
...
if (!conversions.isSimpleType(propertyObj.getClass())) {
// The following line recursively calls writeInternal with the nested object
writePropertyInternal(propertyObj, dbo, prop);
} else {
writeSimpleInternal(propertyObj, dbo, prop);
}
}
writeInternal is called on the top level object, and then recalled recursively for each subobjects (aka SimpleTypes). So they both go through the same logic of adding _id.
Perhaps this is how we should read Spring's documentation:
Mongo's restrictions on Mongo Documents:
MongoDB requires that you have an _id field for all documents. If you
don’t provide one the driver will assign a ObjectId with a generated
value.
Spring Data's restrictions on java classes:
If no field or property specified above is present in the Java class
then an implicit _id file will be generated by the driver but not
mapped to a property or field of the Java class.