Is binding to nested field of a list record supported ?

[albert-kam]

Hi,

Does formio currently support binding a nested list of nestable objects ?

For example i have this mapping:

// MyExample has name and myClasses(List<MyClass>), 
// and MyClass has these fields: name, gender and nestedOnes(List<MyClass>)
FormMapping<MyExample> formMapping = FormUtil.basicBuilder(MyExample.class, "example",
			"name")
		.nested(Forms.basic(MyClass.class, "myClasses", MappingType.LIST)
				.fields("name", "gender")
				.nested(Forms.basic(MyClass.class, "nestedOnes", MappingType.LIST)
							.fields("name", "gender")
							.build())
				.build())
		.build();

And then this tests okay, because it's not trying to bind to the nested props of the list:

@Test
public void testBinding_myClasses() {
	FormData<MyExample> fdata = formMapping.bind(UndertowRequestParams.builder_withBindingPrefix("example")
			.addFormData("name", "Mora Moonsinger")
			.addFormData("myClasses[0]-name", "Kathris Starsong")
			.addFormData("myClasses[0]-gender", "FEMALE")
			.addFormData("myClasses[1]-name", "Adora Nightshade")
			.addFormData("myClasses[1]-gender", "FEMALE")
			.build()
			.debug());
	
	assertEquals(MyExample.builder()
			.withName("Mora Moonsinger")
			.withMyClasses(Lists.newArrayList(
				MyClass.builder()
					.withGender(Gender.FEMALE)
					.withName("Kathris Starsong")
					.build(),
				MyClass.builder()
					.withGender(Gender.FEMALE)
					.withName("Adora Nightshade")
					.build()
			)).build(),
			fdata.getData());
}

But when i try to bind to the nested field of the list record, it fails:

@Test
public void testBinding_myClasses_nestedRecursiveBinding() {
	FormData<MyExample> fdata = formMapping.bind(UndertowRequestParams.builder_withBindingPrefix("example")
			.addFormData("name", "Mora Moonsinger")
			.addFormData("myClasses[0]-name", "Kathris Starsong")
			.addFormData("myClasses[0]-gender", "FEMALE")
			.addFormData("myClasses[0]-nestedOnes[0]-name", "Kathris Starsong Nested")
			.addFormData("myClasses[0]-nestedOnes[0]-gender", "FEMALE")
			.addFormData("myClasses[1]-name", "Adora Nightshade")
			.addFormData("myClasses[1]-gender", "FEMALE")
			.build()
			.debug());
	
	assertEqualsDebug(MyExample.builder()
			.withName("Mora Moonsinger")
			.withMyClasses(Lists.newArrayList(
				MyClass.builder()
					.withGender(Gender.FEMALE)
					.withName("Kathris Starsong")
					.withNestedOnes(Lists.newArrayList(MyClass.builder()
							.withGender(Gender.FEMALE)
							.withName("Kathris Starsong Nested")
							.build()))
					.build(),
				MyClass.builder()
					.withGender(Gender.FEMALE)
					.withName("Adora Nightshade")
					.build()
			)).build(),
			fdata.getData());
}
	

The expected structure is

{
  "name" : "Mora Moonsinger",
  "myClasses" : [ {
    "name" : "Kathris Starsong",
    "gender" : "FEMALE",
    "nestedOnes" : [ {
      "name" : "Kathris Starsong Nested",
      "gender" : "FEMALE",
      "nestedOnes" : [ ]
    } ]
  }, {
    "name" : "Adora Nightshade",
    "gender" : "FEMALE",
    "nestedOnes" : [ ]
  } ]
}

The result structure is this:

{
  "name" : "Mora Moonsinger",
  "myClasses" : [ {
    "name" : "Kathris Starsong",
    "gender" : "FEMALE",
    "nestedOnes" : [ ]
  }, {
    "name" : "Adora Nightshade",
    "gender" : "FEMALE",
    "nestedOnes" : [ ]
  } ]
}

Here is the junit test code. Basically its similar to the above, but with the class and builder definitions.

Any pointers would be greatly appreciated, thank you.

[beranradek]

Hi albert-kam, nice to see you again.

I am afraid nesting of lists mapping within another list mapping is not tested with the library but it could be generally possible. As a hint: Please try to first fill your form mapping with data (using FormMapping.fill method) and print the resulting structure using FormMapping.toString to first better understand generated names of nested form fields. And then possibly debug formMapping.bind (particularly BasicListFormMapping.bind).

[albert-kam]

Hi again !

I tried filling and sysout the filled mapping, and i got this. Maybe there's a tiny bug in it. Please see the YeeHaw in the output to get where it fails.

example : MyExample {
  order : 0,
  fields {
    example-name (value=Mora Moonsinger /count: 1/, order=0)
  }, 
  nested {
    example-myClasses : MyClass {
      order : 1,
      list {
        example-myClasses[0] : MyClass {
          order : 0,
          fields {
            example-myClasses[0]-name (value=Kathris Starsong /count: 1/, order=0),
            example-myClasses[0]-gender (value=FEMALE /count: 1/, order=1)
          }, 
          nested {
            example-myClasses[0]-nestedOnes : MyClass {
              order : 2,
              list {
                // YeeHaw -- should be example-myClasses[0]-nestedOnes[0]
                example-myClasses-nestedOnes[0] : MyClass {
                  order : 0,
                  fields {
                    example-myClasses-nestedOnes[0]-name (value=Kathris Starsong ... /count: 1/, order=0),
                    example-myClasses-nestedOnes[0]-gender (value=FEMALE /count: 1/, order=1)
                  }
                }
              }
            }
          }
        },
        example-myClasses[1] : MyClass {
          order : 1,
          fields {
            example-myClasses[1]-name (value=Adora Nightshade /count: 1/, order=0),
            example-myClasses[1]-gender (value=FEMALE /count: 1/, order=1)
          }, 
          nested {
            example-myClasses[1]-nestedOnes : MyClass {
              order : 2,
            }
          }
        }
      }
    }
  }
}

Any pointers of where the issue might be ?
Thank you !

[albert-kam]

Hi again, sorry to bump this topic.
Is there going to be a followup for this issue ?

[beranradek]

Hi, albert,

I thought that builder.mappingType = MappingType.SINGLE; could be removed from BasicListFormMapping's bind and fillInternal method, but it is not that easy. It is correct when the LIST mapping becomes the SINGLE one with the index field filled up. It needs further investigation/debugging of BasicListFormMapping.bind and BasicFormMapping.getName for your test case. Could you debug BasicFormMapping.getName where the wrong example-myClasses-nestedOnes[0]-name is composed from "property name" of current mapping (with possible index) and name of parent? I don't think I will get to this soon.