Re: How to model this behaviour on multiple aggregates?
"Remy Fannader [email protected] [domaindrivendesign]" <[email protected]> Tue, 21 Jun 2016 22:52:18 +0200
| Newsgroups | gmane.comp.programming.domain-driven-design |
|---|---|
| Message-ID | <CAMdXxPCSu-tTpWF-uwNDdhSSW0feL5QPHbHrcCQQgKJ9h4xbTQ@mail.gmail.com> |
--94eb2c07e9f62453be0535cfff35 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Best is to manage the matrimonial status of persons, not the relationship. https://caminao.wordpress.com/how-to-implement-symbolic-representations/pat= terns/functional-patterns/connector-patterns/ On 21 June 2016 at 11:05, [email protected] [domaindrivendesign] < [email protected]> wrote: > > > We currently have a model where a single aggregate models a Person > (identification, address, etc) and his/her personal relationships > (marriage, partnership, divorces, etc.). This aggregate is fairly large a= nd > not all use cases interested in the relations where operating on the Pers= on > aggregate, we are looking at the consequences of splitting this in two > aggregates (Person and PersonRelation for instance). > > As a consequence, there is no possibility to implement something like > Person.marriesTo(Person.Id anotherPerson). The reason is the constraint > that this is only allowed as long as this relation is not already present > at the given moment (A Person cannot be married twice at the same time). > This is just an example but there a number of constraints on the model wi= th > respect to a Person and his relationships. > > We have identified the following options on how to implement this but are > not satisfied with any of them: > * Create a domain service. This feels unnatural as the behaviour is not > part of the Person that is marrying. > * Implement the behaviour on Person and provide a list of current > relationships, e.g. Person.marriesTo(PersonId anotherPerson, List<Relatio= n> > currentRelations). This enables the Person to implement the required > behaviour, but also requires some state (a set of aggregates) to be > injected. > * Leave the orchestration to the use case implementing the behaviour. Thi= s > also seems wrong, as the domain should be responsible for maintaining its > integrity. A use case creating duplicate relationships cannot be prevente= d > by the domain when using this option. > * Inject the Relation repository into Person, so existing Relation > instances can be requested as part of the implementation. As I understood= , > this is bad practice as well. > > As this seems a rather general problem, I am curious on how you guys woul= d > model this. > > >=20 > --94eb2c07e9f62453be0535cfff35 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable <head> <style type=3D"text/css"> <!-- /* start of attachment style */ .ygrp-photo-title{ clear: both; font-size: smaller; height: 15px; overflow: hidden; text-align: center; width: 75px; } div.ygrp-photo{ background-position: center; background-repeat: no-repeat; background-color: white; border: 1px solid black; height: 62px; width: 62px; } div.photo-title=20 a, div.photo-title a:active, div.photo-title a:hover, div.photo-title a:visited { text-decoration: none;=20 } div.attach-table div.attach-row { clear: both; } div.attach-table div.attach-row div { float: left; /* margin: 2px;*/ } p { clear: both; padding: 15px 0 3px 0; overflow: hidden; } div.ygrp-file { width: 30px; valign: middle; } div.attach-table div.attach-row div div a { text-decoration: none; } div.attach-table div.attach-row div div span { font-weight: normal; } div.ygrp-file-title { font-weight: bold; } /* end of attachment style */ --> </style> </head> <html> <head> <style type=3D"text/css"> <!-- #ygrp-mkp { border: 1px solid #d8d8d8; font-family: Arial; margin: 10px 0; padding: 0 10px; } #ygrp-mkp hr { border: 1px solid #d8d8d8; } #ygrp-mkp #hd { color: #628c2a; font-size: 85%; font-weight: 700; line-height: 122%; margin: 10px 0; } #ygrp-mkp #ads { margin-bottom: 10px; } #ygrp-mkp .ad { padding: 0 0; } #ygrp-mkp .ad p { margin: 0; } #ygrp-mkp .ad a { color: #0000ff; text-decoration: none; } --> </style> </head> <body> <!-- |**|begin egp html banner|**| --> <br><br> <!-- |**|end egp html banner|**| --> <div dir=3D"ltr"><div class=3D"gmail_default" style=3D"font-size:small">Bes= t is to manage the matrimonial status of persons, not the relationship.</di= v><div class=3D"gmail_default" style=3D""><a href=3D"https://caminao.wordpr= ess.com/how-to-implement-symbolic-representations/patterns/functional-patte= rns/connector-patterns/">https://caminao.wordpress.com/how-to-implement-sym= bolic-representations/patterns/functional-patterns/connector-patterns/</a><= br></div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">On= 21 June 2016 at 11:05, <a href=3D"mailto:[email protected]">denni= [email protected]</a> [domaindrivendesign] <span dir=3D"ltr"><<a hre= f=3D"mailto:[email protected]" target=3D"_blank">domaindri= [email protected]</a>></span> wrote:<br><blockquote class=3D"gma= il_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-lef= t:1ex"> <u></u> =20 <div style=3D"background-color:#fff"> <span>=C2=A0</span> <div> <div> <div> =20=20=20=20=20=20 =20=20=20=20=20=20 <p>We currently have a model where a single aggregate models a Person= (identification, address, etc) and his/her personal relationships (marriag= e, partnership, divorces, etc.). This aggregate is fairly large and not all= use cases interested in the relations where operating on the Person aggreg= ate, we are looking at the consequences of splitting this in two aggregates= (Person and PersonRelation for instance).<br><br>As a consequence, there i= s no possibility to implement something like Person.marriesTo(Person.Id ano= therPerson). The reason is the constraint that this is only allowed as long= as this relation is not already present at the given moment (A Person cann= ot be married twice at the same time). This is just an example but there a = number of constraints on the model with respect to a Person and his relatio= nships.<br><br>We have identified the following options on how to implement= this but are not satisfied with any of them:<br>* Create a domain service.= This feels unnatural as the behaviour is not part of the Person that is ma= rrying.<br>* Implement the behaviour on Person and provide a list of curren= t relationships, e.g. Person.marriesTo(PersonId anotherPerson, List<Rela= tion> currentRelations). This enables the Person to implement the requir= ed behaviour, but also requires some state (a set of aggregates) to be inje= cted.<br>* Leave the orchestration to the use case implementing the behavio= ur. This also seems wrong, as the domain should be responsible for maintain= ing its integrity. A use case creating duplicate relationships cannot be pr= evented by the domain when using this option.<br>* Inject the Relation repo= sitory into Person, so existing Relation instances can be requested as part= of the implementation. As I understood, this is bad practice as well.<br><= br>As this seems a rather general problem, I am curious on how you guys wou= ld model this.<br></p><p><span><br></span></p><p></p> </div> =20=20=20=20=20 =20=20=20=20 <div style=3D"color:#fff;min-height:0"></div> </div> =20=20 </blockquote></div><br></div> <!-- |**|begin egp html banner|**| --> <br> <br> <!-- |**|end egp html banner|**| --> <div width=3D"1" style=3D"color: white; clear: both;"/>__._,_.___</div> =20=20=20=20=20=20 =20=20 =20=20=20=20 <div id=3D"fromDMARC" style=3D"clear:both; margin-top: 10px;"> <hr style=3D"height:2px ; border-width:0; color:#E3E3E3; backgroun= d-color:#E3E3E3;"> Posted by: Remy Fannader <[email protected]> <hr sty= le=3D"height:2px ; border-width:0; color:#E3E3E3; background-color:#E3E3E3;= "> </div> <!-- Start Recommendations --> <!-- End Recommendations --> <!-- |**|begin egp html banner|**| --> <img src=3D"http://geo.yahoo.com/serv?s=3D97476590/grpId=3D8116923/grpspI= d=3D1705007181/msgId=3D24774/stime=3D1466542340" width=3D"1" height=3D"1"> = <br> <!-- |**|end egp html banner|**| --> =20=20 <!-- |**|begin egp html banner|**| --> <br> =20=20=20 =20=20=20=20=20 =20 <!-- |**|begin egp html banner|**| --> <div id=3D"ygrp-vital" style=3D"background-color: #f2f2f2; font-fam= ily: Verdana; font-size: 10px; margin-bottom: 10px; padding: 10px;"> <span id=3D"vithd" style=3D"font-weight: bold; color: #333; text-tr= ansform: uppercase; "><a href=3D"https://groups.yahoo.com/neo/groups/domain= drivendesign/info;_ylc=3DX3oDMTJlbmRkZTIwBF9TAzk3MzU5NzE0BGdycElkAzgxMTY5Mj= MEZ3Jwc3BJZAMxNzA1MDA3MTgxBHNlYwN2dGwEc2xrA3ZnaHAEc3RpbWUDMTQ2NjU0MjM0MA--"= style=3D"text-decoration: none;">Visit Your Group</a></span> <ul style=3D"list-style-type: none; margin: 0; padding: 0; display: in= line;"> <li style=3D"border-right: 1px solid #000; font-weight: 700; di= splay: inline; padding: 0 5px; margin-left: 0;"> <span class=3D"cat"><a href=3D"https://groups.yahoo.com/neo/groups/do= maindrivendesign/members/all;_ylc=3DX3oDMTJmYWVtaXBmBF9TAzk3MzU5NzE0BGdycEl= kAzgxMTY5MjMEZ3Jwc3BJZAMxNzA1MDA3MTgxBHNlYwN2dGwEc2xrA3ZtYnJzBHN0aW1lAzE0Nj= Y1NDIzNDA-" style=3D"text-decoration: none;">New Members</a></span> <span class=3D"ct" style=3D"color: #ff7900;">1</span> </li> </ul> </div> <div id=3D"ft" style=3D"font-family: Arial; font-size: 11px; margin-top: 5p= x; padding: 0 2px 0 0; clear: both;"> <a href=3D"https://groups.yahoo.com/neo;_ylc=3DX3oDMTJkcWRwbG9nBF9TAzk3ND= c2NTkwBGdycElkAzgxMTY5MjMEZ3Jwc3BJZAMxNzA1MDA3MTgxBHNlYwNmdHIEc2xrA2dmcARzd= GltZQMxNDY2NTQyMzQw" style=3D"float: left;"><img src=3D"http://l.yimg.com/r= u/static/images/yg/img/email/new_logo/logo-groups-137x15.png" height=3D"15"= width=3D"137" alt=3D"Yahoo! 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