Based on the reconstruction of the pet store project, the original project was separated from the backing, and the project code was attached at the end of the article
RESTful API design
API design demo
Springboot engineering
ORM we use Mybatis -plus, introduce a variety of dependencies, configuration file configuration, nothing special, omitted here.
Creating a New Entity Class
Entity class annotation configuration
Please refer to mybaitS-Plus website for details
Project database table:
@TableName(value = "category")
public class Category {
@TableId(value = "catid", type = IdType.INPUT)
private String categoryId;
@TableField(value = "name")
private String name;
@TableField(value = "descn")
private String description;
}
Copy the codeWrite the Mapper class
Inheritance BaseMapper
public interface CategoryMapper extends BaseMapper<Category> {}Copy the codeStart the class with the @mapperscan annotation
Write test classes and perform tests
6
[Category(categoryId=, name=, description=<image src='/images/birds_icon.gif'><font size='5' color='blue'> Birds</font>), Category(categoryId=BIRDS, name=Birds, description=<image src="./images/birds_icon.gif"><font size="5" color="blue"> Birds</font>), Category(categoryId=CATS, name=Cats, description=<image src="/images/cats_icon.gif"><font size="5" color="blue"> Cats</font>), Category(categoryId=DOGS, name=Dogs, description=<image src="/images/dogs_icon.gif"><font size="5" color="blue"> Dogs</font>), Category(categoryId=FISH, name=Fish, description=<image src="/images/fish_icon.gif"><font size="5" color="blue"> Fish</font>), Category(categoryId=REPTILES, name=Reptiles, description=<image src="/images/reptiles_icon.gif"><font size="5" color="blue"> Reptiles</font>)]
Copy the code
successful
Design of common response
I won’t go into the Controller and service layer implementations here
Write CommonResponse class, this kind of design according to the original RESTful API design implementation
public class CommonResponse<T> implements Serializable {
private int status;
private String msg;
private T data;
public CommonResponse(int status){
this.status=status;
}
public CommonResponse(int status,String msg){
this.status = status;
this.msg=msg;
}
public CommonResponse(int status,String msg,T data){
this.status = status;
this.msg=msg;
this.data=data;
}
public CommonResponse(int status,T data){
this.status = status;
this.data=data; }}Copy the codeThis is the original design, but one problem with this design is that only the second constructor can be called when passing integers and strings as parameters.
The tests are as follows:
The improvements are as follows:
public class CommonResponse<T> implements Serializable {
private int status;
private String msg;
private T data;
private CommonResponse(int status){
this.status=status;
}
private CommonResponse(int status,String msg){
this.status = status;
this.msg=msg;
}
private CommonResponse(int status,String msg,T data){
this.status = status;
this.msg=msg;
this.data=data;
}
private CommonResponse(int status,T data){
this.status = status;
this.data=data;
}
public static <T> CommonResponse<T> creatForSuccess(a){
return new CommonResponse<T>(0);
}
public static <T> CommonResponse<T> creatForSuccess(T date){
return new CommonResponse<T>(0,date);
}
public static <T> CommonResponse<T> creatForSuccess(String msg,T date){
return new CommonResponse<T>(0,msg,date);
}
public static <T> CommonResponse<T> creatForSuccessMessage(String msg){
return new CommonResponse<T>(0,msg);
}
public static <T> CommonResponse<T> creatForError(String msg){
return new CommonResponse<T>(1,msg); }}Copy the codeMake the constructor private and assign through the static method below
This completes the design of the universal response
public class CatalogServiceImpl implements CatalogService {
@Autowired
private CategoryMapper categoryMapper;
@Override
public CommonResponse<List<Category>> getCategoryList() {
List<Category> categoryList = categoryMapper.selectList(null);
if (categoryList.isEmpty()){
return CommonResponse.creatForSuccessMessage("No species information found.");// Not found but still in successful state
}
else{
returnCommonResponse.creatForSuccess(categoryList); }}}Copy the codeThe above code is the service layer, and the following error occurs at runtime:
No converter found for return value of type: class com.xiesuper.common.CommonResponse]
Copy the codeThe CommonResponse class did not add the @getter annotation (which introduced the lambook dependency).
The resulting JSON data is as follows:
{
"status": 0."msg": null."data": [{"categoryId": "BIRDS"."name": "Birds"."description": "<image src=\"./images/birds_icon.gif\"><font size=\"5\" color=\"blue\"> Birds</font>"
},
{
"categoryId": "CATS"."name": "Cats"."description": "<image src=\"/images/cats_icon.gif\"><font size=\"5\" color=\"blue\"> Cats</font>"
},
{
"categoryId": "DOGS"."name": "Dogs"."description": "<image src=\"/images/dogs_icon.gif\"><font size=\"5\" color=\"blue\"> Dogs</font>"
},
{
"categoryId": "FISH"."name": "Fish"."description": "<image src=\"/images/fish_icon.gif\"><font size=\"5\" color=\"blue\"> Fish</font>"
},
{
"categoryId": "REPTILES"."name": "Reptiles"."description": "<image src=\"/images/reptiles_icon.gif\"><font size=\"5\" color=\"blue\"> Reptiles</font>"}}]Copy the codeHere we don’t assign to MSG, but eventually get the MSG data. Solution: add annotations to the CommonResponse class
//Json serialized spacetime data will not be included
@JsonInclude(JsonInclude.Include.NON_NULL)
Copy the codeWhat if the information in the entity class doesn’t come from a table?
Let’s look at the variable in the original pet store Item class:
private String itemId;
private String productId;
private BigDecimal listPrice;
private BigDecimal unitCost;
private int supplierId;
private String status;
private String attribute1;
private String attribute2;
private String attribute3;
private String attribute4;
private String attribute5;
private Product product;
private int quantity;
Copy the codeThe information comes from three tables:
The item list:
The inventory table:
One solution is join queries for SQL statements, but this is not recommended by Mybatis – Plus
Let’s solve this problem:
First of all, we need to learn the concepts of VO, BO, DTO and DO: brief analysis of VO, BO, DTO and DO
VO is view object, which is also the object to be displayed in our page. At this time, we use VO to query Item information. Here, we use VO to query all Items under a productId as an example
New Item, Product, ItemInventory entity class, as well as Itemmapper Productmapper, ItemInventoryMapper specific code is no longer the shows. New ItemVo:
Fill in ItemVo information:
@Data
public class ItemVo {
//item specifies the fields in the table
private String itemId;
private String productId;
private BigDecimal listPrice;
private BigDecimal unitCost;
private int supplierId;
private String status;
private String attribute1;
private String attribute2;
private String attribute3;
private String attribute4;
private String attribute5;
// Item belongs to the product property
private String categoryId;
private String name;
private String description;
/ / item inventory
private int quantity;
}
Copy the codeFirst, we need to obtain the items from the Item table in the database according to productId, then obtain the product information, then obtain the inventory information, so the question is how to obtain the items from the productId table?
At this point we use the conditional constructor in Mybatis – Plus
Conditional constructor
The key code implementation is as follows
QueryWrapper<Item> queryWrapper = new QueryWrapper<>();// Conditional constructor
queryWrapper.eq("productId",productId);// The parameters are the field name and the value passed in
List<Item> itemList = itemMapper.selectList(queryWrapper);
Copy the codeItemVo = ItemVo = ItemVo = ItemVo
@Override
public CommonResponse<List<ItemVo>> getItemsByProductId(String productId) {
QueryWrapper<Item> queryWrapper = new QueryWrapper<>();// Conditional constructor
queryWrapper.eq("productId",productId);// The parameters are the field name and the value passed in
List<Item> itemList = itemMapper.selectList(queryWrapper);
if(itemList.isEmpty()){
return CommonResponse.creatForSuccessMessage("Corresponding ProductId has no items information");
}
Product product =productMapper.selectById(productId);
List<ItemVo> itemVoList = new ArrayList<>();
for(Item item:itemList){
ItemVo itemVo = itemToItemVo(item,product);
itemVoList.add(itemVo);
}
return CommonResponse.creatForSuccess(itemVoList);
}
private ItemVo itemToItemVo(Item item,Product product){
ItemVo itemVo =new ItemVo();
itemVo.setItemId(item.getItemId());
itemVo.setProductId(item.getProductId());
itemVo.setUnitCost(item.getUnitCost());
itemVo.setListPrice(item.getListPrice());
itemVo.setSupplierId(item.getSupplierId());
itemVo.setStatus(item.getStatus());
item.setAttribute1(item.getAttribute1());
item.setAttribute2(item.getAttribute2());
item.setAttribute3(item.getAttribute3());
item.setAttribute4(item.getAttribute4());
item.setAttribute5(item.getAttribute5());
itemVo.setDescription(product.getDescription());
itemVo.setCategoryId(product.getCategoryId());
itemVo.setName(product.getName());
ItemInventory itemInventory = itemInventoryMapper.selectById(item.getItemId());
itemVo.setQuantity(itemInventory.getQuantity());
return itemVo;
}
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