Refactor FieldContainer to allow queries on subset of field chain

Author: bkoelman

src/Examples/GettingStarted/GettingStarted.http

@@ -9,28 +9,39 @@ GET http://{{hostname}}:{{port}}/api/people
 
 GET http://{{hostname}}:{{port}}/api/people?include=books
 
-### Filter inside compound attribute
+### Filter inside compound attribute chain
 
-GET http://{{hostname}}:{{port}}/api/people?filter=startsWith(livingAddress.country,'T')
+GET http://{{hostname}}:{{port}}/api/people?filter=startsWith(livingAddress.country.code,'N')
 
-### TODO: Test filters descending into compound attribute (requires an expression that has child scope: "has").
-### TODO: Consider supporting to-many filters on collections: "has", "any", "count"
-###         Requires to act on parent Attr instead of ResourceType, which likely requires major breaking change.
+### Filter on collection attribute with "count" function
 
+GET http://{{hostname}}:{{port}}/api/people?filter=greaterThan(count(namesOfChildren),'2')
+
+### Filter on collection attribute with "has" function
+
+GET http://{{hostname}}:{{port}}/api/people?filter=not(has(addresses))
+
+### Filter on collection attribute with "has" function, taking nested filter
+
+GET http://{{hostname}}:{{port}}/api/people?filter=has(addresses,equals(country.code,'ESP'))
 
 ### Patch string collection attribute
 
 PATCH http://{{hostname}}:{{port}}/api/people/1
 Content-Type: application/vnd.api+json
 
 {
-    "data": {
-        "type": "people",
-        "id": "1",
-        "attributes": {
-            "namesOfChildren": ["Mary", "Ann", null]
-        }
+  "data": {
+    "type": "people",
+    "id": "1",
+    "attributes": {
+      "namesOfChildren": [
+        "Mary",
+        "Ann",
+        null
+      ]
     }
+  }
 }
 
 ### Patch int collection attribute
@@ -39,13 +50,17 @@ PATCH http://{{hostname}}:{{port}}/api/people/1
 Content-Type: application/vnd.api+json
 
 {
-    "data": {
-        "type": "people",
-        "id": "1",
-        "attributes": {
-            "agesOfChildren": [15, 25, null]
-        }
+  "data": {
+    "type": "people",
+    "id": "1",
+    "attributes": {
+      "agesOfChildren": [
+        15,
+        25,
+        null
+      ]
     }
+  }
 }
 
 ### Patch members of compound attribute
@@ -54,16 +69,19 @@ PATCH http://{{hostname}}:{{port}}/api/people/1
 Content-Type: application/vnd.api+json
 
 {
-    "data": {
-        "type": "people",
-        "id": "1",
-        "attributes": {
-            "livingAddress": {
-                "country": "Germany",
-                 "street": "OtherStreet"
-            }
-        }
+  "data": {
+    "type": "people",
+    "id": "1",
+    "attributes": {
+      "livingAddress": {
+        "country": {
+          "code": "ITA",
+          "displayName": "Italy"
+        },
+        "street": "OtherStreet"
+      }
     }
+  }
 }
 
 ### Patch members of compound attribute, setting them to null
@@ -72,16 +90,16 @@ PATCH http://{{hostname}}:{{port}}/api/people/1
 Content-Type: application/vnd.api+json
 
 {
-    "data": {
-        "type": "people",
-        "id": "1",
-        "attributes": {
-            "livingAddress": {
-                "country": null,
-                 "street": null
-            }
-        }
+  "data": {
+    "type": "people",
+    "id": "1",
+    "attributes": {
+      "livingAddress": {
+        "country": null,
+        "street": null
+      }
     }
+  }
 }
 
 ### Patch compound attribute to empty object (must be a no-op)
@@ -90,13 +108,13 @@ PATCH http://{{hostname}}:{{port}}/api/people/1
 Content-Type: application/vnd.api+json
 
 {
-    "data": {
-        "type": "people",
-        "id": "1",
-        "attributes": {
-            "mailAddress": {}
-        }
+  "data": {
+    "type": "people",
+    "id": "1",
+    "attributes": {
+      "mailAddress": {}
     }
+  }
 }
 
 ### Patch compound attribute to null
@@ -105,13 +123,13 @@ PATCH http://{{hostname}}:{{port}}/api/people/1
 Content-Type: application/vnd.api+json
 
 {
-    "data": {
-        "type": "people",
-        "id": "1",
-        "attributes": {
-            "mailAddress": null
-        }
+  "data": {
+    "type": "people",
+    "id": "1",
+    "attributes": {
+      "mailAddress": null
     }
+  }
 }
 
 ### Patch compound nullable collection attribute (null element is blocked by EF Core)
@@ -120,19 +138,24 @@ PATCH http://{{hostname}}:{{port}}/api/people/1
 Content-Type: application/vnd.api+json
 
 {
-    "data": {
-        "type": "people",
-        "id": "1",
-        "attributes": {
-            "addresses": [{
-                    "country": "Germany"
-                }, {
-                    "street": "SomeStreet"
-                }, {
-                }
-            ]
-        }
+  "data": {
+    "type": "people",
+    "id": "1",
+    "attributes": {
+      "addresses": [
+        {
+          "country": {
+            "code": "DEU",
+            "displayName": "Germany"
+          }
+        },
+        {
+          "street": "SomeStreet"
+        },
+        {}
+      ]
     }
+  }
 }
 
 ### Patch relationships to null - SHOULD THIS FAIL OR NO-OP?
@@ -141,9 +164,9 @@ PATCH http://{{hostname}}:{{port}}/api/people/1
 Content-Type: application/vnd.api+json
 
 {
-    "data": {
-        "type": "people",
-        "id": "1",
-        "relationships": null
-    }
+  "data": {
+    "type": "people",
+    "id": "1",
+    "relationships": null
+  }
 }

src/Examples/GettingStarted/Models/Address.cs

@@ -12,8 +12,8 @@ public sealed class Address
     [Attr]
     public string? PostalCode { get; set; }
 
-    [Attr]
-    public string? Country { get; set; }
+    [Attr(IsCompound = true)]
+    public Country? Country { get; set; }
 
     public string? NotExposed { get; set; }
 }

src/Examples/GettingStarted/Models/Country.cs

@@ -0,0 +1,14 @@
+using JsonApiDotNetCore.Resources.Annotations;
+using Microsoft.EntityFrameworkCore;
+
+namespace GettingStarted.Models;
+
+[Owned]
+public sealed class Country
+{
+    [Attr]
+    public required string Code { get; set; }
+
+    [Attr]
+    public string? DisplayName { get; set; }
+}

src/Examples/GettingStarted/Program.cs

@@ -5,6 +5,8 @@
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Diagnostics;
 
+#pragma warning disable format
+
 WebApplicationBuilder builder = WebApplication.CreateBuilder(args);
 
 // Add services to the container.
@@ -74,14 +76,22 @@ static async Task CreateSampleDataAsync(SampleDbContext dbContext)
                 {
                     Street = "SomeStreet",
                     PostalCode = "1234 AB",
-                    Country = "The Netherlands",
+                    Country = new Country
+                    {
+                        Code = "NLD",
+                        DisplayName = "The Netherlands"
+                    },
                     NotExposed = "NotExposed"
                 },
                 MailAddress = new Address
                 {
                     Street = "MailStreet",
                     PostalCode = "MailPostalCode",
-                    Country = "MailCountry",
+                    Country = new Country
+                    {
+                        Code = "MailCode",
+                        DisplayName = "MailCountryName"
+                    },
                     NotExposed = "MailNotExposed"
                 },
                 Addresses =
@@ -90,14 +100,22 @@ static async Task CreateSampleDataAsync(SampleDbContext dbContext)
                     {
                         Street = "Street1",
                         PostalCode = "PostalCode1",
-                        Country = "Country1",
+                        Country = new Country
+                        {
+                            Code = "ESP",
+                            DisplayName = "Spain"
+                        },
                         NotExposed = "NotExposed1"
                     },
                     new Address
                     {
                         Street = "Street2",
                         PostalCode = "PostalCode2",
-                        Country = "Country2",
+                        Country = new Country
+                        {
+                            Code = "Country2",
+                            DisplayName = "CountryName2"
+                        },
                         NotExposed = "NotExposed2"
                     }
                 ],
@@ -135,6 +153,7 @@ static async Task CreateSampleDataAsync(SampleDbContext dbContext)
             }
         }*/
     );
+#pragma warning restore format
 
     await dbContext.SaveChangesAsync();
 }

src/JsonApiDotNetCore.Annotations/Configuration/IFieldContainer.cs

@@ -0,0 +1,30 @@
+using JsonApiDotNetCore.Resources.Annotations;
+
+namespace JsonApiDotNetCore.Configuration;
+
+/// <summary>
+/// The containing type for a JSON:API field, which can be a <see cref="ResourceType" /> or an <see cref="AttrAttribute" />.
+/// </summary>
+public interface IFieldContainer
+{
+    /// <summary>
+    /// The publicly exposed name of this container.
+    /// </summary>
+    string PublicName { get; }
+
+    /// <summary>
+    /// The CLR type of this container.
+    /// </summary>
+    Type ClrType { get; }
+
+    /// <summary>
+    /// Searches the direct children of this container for an attribute with the specified name.
+    /// </summary>
+    /// <param name="publicName">
+    /// The publicly exposed name of the attribute to find.
+    /// </param>
+    /// <returns>
+    /// The attribute, or <c>null</c> if not found.
+    /// </returns>
+    AttrAttribute? FindAttributeByPublicName(string publicName);
+}

src/JsonApiDotNetCore.Annotations/Configuration/ResourceType.cs

@@ -7,7 +7,7 @@ namespace JsonApiDotNetCore.Configuration;
 /// Metadata about the shape of a JSON:API resource in the resource graph.
 /// </summary>
 [PublicAPI]
-public sealed class ResourceType
+public sealed class ResourceType : IFieldContainer
 {
     private static readonly IReadOnlySet<ResourceType> EmptyResourceTypeSet = new HashSet<ResourceType>().AsReadOnly();
     private static readonly IReadOnlySet<AttrAttribute> EmptyAttributeSet = new HashSet<AttrAttribute>().AsReadOnly();

src/JsonApiDotNetCore.Annotations/Resources/Annotations/AttrAttribute.cs

@@ -1,5 +1,6 @@
 using System.Collections.ObjectModel;
 using JetBrains.Annotations;
+using JsonApiDotNetCore.Configuration;
 
 namespace JsonApiDotNetCore.Resources.Annotations;
 
@@ -8,7 +9,7 @@ namespace JsonApiDotNetCore.Resources.Annotations;
 /// </summary>
 [PublicAPI]
 [AttributeUsage(AttributeTargets.Property)]
-public sealed class AttrAttribute : ResourceFieldAttribute
+public sealed class AttrAttribute : ResourceFieldAttribute, IFieldContainer
 {
     private static readonly ReadOnlyDictionary<string, AttrAttribute> EmptyChildren = new Dictionary<string, AttrAttribute>().AsReadOnly();
 
@@ -49,6 +50,15 @@ public AttrCapabilities Capabilities
     /// </summary>
     public IReadOnlyDictionary<string, AttrAttribute> Children { get; internal set; } = EmptyChildren;
 
+    /// <inheritdoc />
+    public Type ClrType => Property.PropertyType;
+
+    /// <inheritdoc />
+    public AttrAttribute? FindAttributeByPublicName(string publicName)
+    {
+        return Children.GetValueOrDefault(publicName);
+    }
+
     /// <inheritdoc />
     public override bool Equals(object? obj)
     {