adding constraint validation example

src/main/java/guru/springframework/sfgrestdocsexample/web/model/BeerDto.java

@@ -5,10 +5,7 @@ import lombok.Builder;
 import lombok.Data;
 import lombok.NoArgsConstructor;
 
-import javax.validation.constraints.NotBlank;
+import javax.validation.constraints.*;
-import javax.validation.constraints.NotNull;
-import javax.validation.constraints.Null;
-import javax.validation.constraints.Positive;
 import java.math.BigDecimal;
 import java.time.OffsetDateTime;
 import java.util.UUID;
@@ -36,6 +33,7 @@ public class BeerDto {
     private OffsetDateTime lastModifiedDate;
 
     @NotBlank
+    @Size(min = 3, max = 100)
     private String beerName;
 
     @NotNull
@@ -49,6 +47,7 @@ public class BeerDto {
     @NotNull
     private BigDecimal price;
 
+    @Positive
     private Integer quantityOnHand;
 
 }

src/test/java/guru/springframework/sfgrestdocsexample/web/controller/BeerControllerTest.java

@@ -14,7 +14,10 @@ import org.springframework.boot.test.mock.mockito.MockBean;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.http.MediaType;
 import org.springframework.restdocs.RestDocumentationExtension;
+import org.springframework.restdocs.constraints.ConstraintDescriptions;
+import org.springframework.restdocs.payload.FieldDescriptor;
 import org.springframework.test.web.servlet.MockMvc;
+import org.springframework.util.StringUtils;
 
 import java.math.BigDecimal;
 import java.util.Optional;
@@ -26,6 +29,7 @@ import static org.springframework.restdocs.mockmvc.MockMvcRestDocumentation.docu
 import static org.springframework.restdocs.mockmvc.RestDocumentationRequestBuilders.*;
 import static org.springframework.restdocs.payload.PayloadDocumentation.*;
 import static org.springframework.restdocs.request.RequestDocumentation.*;
+import static org.springframework.restdocs.snippet.Attributes.key;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
 
 //import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
@@ -78,21 +82,23 @@ class BeerControllerTest {
         BeerDto beerDto =  getValidBeerDto();
         String beerDtoJson = objectMapper.writeValueAsString(beerDto);
 
+        ConstrainedFields fields = new ConstrainedFields(BeerDto.class);
+
         mockMvc.perform(post("/api/v1/beer/")
                 .contentType(MediaType.APPLICATION_JSON)
                 .content(beerDtoJson))
                 .andExpect(status().isCreated())
                 .andDo(document("v1/beer",
                         requestFields(
-                                fieldWithPath("id").ignored(),
+                                fields.withPath("id").ignored(),
-                                fieldWithPath("version").ignored(),
+                                fields.withPath("version").ignored(),
-                                fieldWithPath("createdDate").ignored(),
+                                fields.withPath("createdDate").ignored(),
-                                fieldWithPath("lastModifiedDate").ignored(),
+                                fields.withPath("lastModifiedDate").ignored(),
-                                fieldWithPath("beerName").description("Name of the beer"),
+                                fields.withPath("beerName").description("Name of the beer"),
-                                fieldWithPath("beerStyle").description("Style of Beer"),
+                                fields.withPath("beerStyle").description("Style of Beer"),
-                                fieldWithPath("upc").description("Beer UPC").attributes(),
+                                fields.withPath("upc").description("Beer UPC").attributes(),
-                                fieldWithPath("price").description("Beer Price"),
+                                fields.withPath("price").description("Beer Price"),
-                                fieldWithPath("quantityOnHand").ignored()
+                                fields.withPath("quantityOnHand").ignored()
                         )));
     }
 
@@ -117,4 +123,19 @@ class BeerControllerTest {
 
     }
 
+    private static class ConstrainedFields {
+
+        private final ConstraintDescriptions constraintDescriptions;
+
+        ConstrainedFields(Class<?> input) {
+            this.constraintDescriptions = new ConstraintDescriptions(input);
+        }
+
+        private FieldDescriptor withPath(String path) {
+            return fieldWithPath(path).attributes(key("constraints").value(StringUtils
+                    .collectionToDelimitedString(this.constraintDescriptions
+                            .descriptionsForProperty(path), ". ")));
+        }
+    }
+
 }

src/test/resources/org/springframework/restdocs/templates/request-fields.snippet

@@ -0,0 +1,11 @@
+    |===
+        |Path|Type|Description|Constraints
+
+    {{#fields}}
+        |{{path}}
+        |{{type}}
+        |{{description}}
+        |{{constraints}}
+
+    {{/fields}}
+        |===