In Automapper, we normally have 1 to 1 mapping defined but I have a case whereas the incoming stream as a json payload which then I cast it as a dynamic (using JObject parse) and in one of the property within the payload it defined which object that it needs to cast into. Lets take a look at the sample below
Input
Json payload to create a city
[code language=”javascript”]
{
"requestId": "C4910016-C30D-415C-89D3-D08D724429A6",
"messageType": "CITY_CREATED",
"categoryName": "categoryA",
"metadata": {
"city": "sydney",
"state": "NSW",
"postcode": "2000",
"country": "australia"
}
}
[/code]
at the same time we can also have a Json payload to create a staff
[code language=”javascript”]
{
"requestId":"C4910016-C30D-415C-89D3-D08D724429A6",
"messageType": "STAFF_CREATED",
"categoryName": "categoryB",
"staffDetail": {
"name": "fransiscus",
"dateOfBirth": "01/01/1950"
},
"location" : {
"cityId" : "1"
}
}
[/code]
So what we are doing in here, all the message will go into payload property (it can contain any object) and we add some extra information/header/metadata on the parent level
Desired Outputs
[code language=”javascript”]
{
"messageType": "CITY_CREATED",
"payload": {
"city": "sydney",
"state": "NSW",
"postcode": "2000",
"country": "australia"
},
"provider": "abc",
"providerRequestId": "C4910016-C30D-415C-89D3-D08D724429A6",
"receivedAt": "2015-09-30T23:53:58.6118521Z",
"lastUpdated": "2015-09-30T23:53:58.6128283Z",
"lastUpdater": "Transformer",
"attempt": 0
}
[/code]
[code language=”javascript”]
{
"messageType": "STAFF_CREATED",
"payload": {
"staffName": "fransiscus",
"dateOfBirth": "01/01/1950",
"cityId": "1"
},
"provider": "abc",
"providerRequestId": "C4910016-C30D-415C-89D3-D08D724429A6",
"receivedAt": "2015-09-30T23:53:58.6118521Z",
"lastUpdated": "2015-09-30T23:53:58.6128283Z",
"lastUpdater": "Transformer",
"attempt": 0
}
[/code]
To map this to a concrete class 1:1 mapping is straight forward and easy. The problem here is that the “messageType” is the one that decided which object that it should be
Automapper Configuration:
1. POCO object
abstract class that stores all the metadata
[code language=”csharp”]
public abstract class Metadata
{
public string MessageType { get; set; }
public string Provider { get; set; }
public string ProviderRequestId { get; set; }
public DateTime ReceivedAt { get; set; }
public DateTime LastUpdated { get; set; }
public string LastUpdater { get; set; }
public int Attempt { get; set; }
public List<string> Errors { get; set; }
}
[/code]
[code language=”csharp”]
public class City
{
public string CityName { get; set; }
public string State { get; set; }
public string PostCode { get; set; }
public string Country { get; set; }
}
[/code]
[code language=”csharp”]
public class StaffDetail
{
public string Name { get; set; }
public string DateOfBirth { get; set; }
public int CityId { get; set; }
}
[/code]
[code language=”csharp”]
public class Message<T> : Metadata where T : class
{
public T Payload { get; set; }
}
[/code]
2. Lets create a TypeConverter for the base class which is Metadata and from this converter it will return the derived class
[code language=”csharp”]
public class MetadataTypeConverter : TypeConverter<dynamic, Metadata>
{
protected override Metadata ConvertCore(dynamic source)
{
Metadata metadata;
var type = (string)source.messageType.Value;
switch (type)
{
case "STAFF_CREATED":
metadata = new Message<StaffDetail> { Payload = Mapper.Map<dynamic, StaffDetail>(source) };
break;
case "CITY_CREATED":
metadata = new Message<City> { Payload = Mapper.Map<dynamic, City>(source) };
break;
default: throw new Exception(string.Format("no mapping defined for {0}", source.messageType.Value));
}
metadata.ProviderRequestId = source.requestId;
metadata.Topic = string.Format("{0}.{1}.pregame",
producerTopicName,
source.categoryName ?? source.competition.categoryName);
metadata.Provider = "My Provider";
metadata.MessageType = source.messageType;
metadata.ReceivedAt = DateTime.UtcNow;
metadata.LastUpdated = DateTime.UtcNow;
metadata.LastUpdater = "Transformer";
metadata.Attempt = 0;
return metadata;
}
}
[/code]
3. Lets create a TypeConverter for the derived class which are Staff and City
[code language=”csharp”]
public class CityTypeConverter : TypeConverter<dynamic, City>
{
protected override City ConvertCore(dynamic source)
{
City city = new City();
city.CityName = source.metadata.city;
city.State = source.metadata.state;
city.Postcode = source.metadata.postcode;
city.Country = source.metadata.country;
return city;
}
}
[/code]
[code language=”csharp”]
public class StaffDetailTypeConverter : TypeConverter<dynamic, StaffDetail>
{
protected override StaffDetail ConvertCore(dynamic source)
{
StaffDetail staffdetail = new StaffDetail();
staffdetail.Name = source.staffDetail.name;
staffdetail.DateOfBirth = source.staffDetail.dateOfBirth;
staffdetail.CityId = source.location.cityId;
return staffdetail;
}
}
[/code]
3. Define the Automapper mapping in the configuration
[code language=”csharp”]
public class WhafflMessageMapping : Profile
{
public override string ProfileName
{
get
{
return this.GetType().Name;
}
}
protected override void Configure()
{
this.CreateMap()
.ConvertUsing(new MetadataTypeConverter());
this.CreateMap()
.ConvertUsing(new StaffDetailTypeConverter());
this.CreateMap()
.ConvertUsing(new CityTypeConverter());
}
private Metadata BuildWhafflMessage(dynamic context)
{
var type = ((string)context.messageType.Value);
switch (type)
{
case "STAFF_CREATED":
return new Message { Payload = Mapper.Map(context) };
case "CITY_CREATED:
return new Message { Payload = Mapper.Map(context) };
default: throw new Exception(string.Format("no mapping defined for {0}", context.messageType.Value));
}
}
}
[/code]
