entity framework - EF7 Read Master Detail Records -

i'm trying head around ef7 writing simple master-detail relationship sqlite database. saving works fine, reading gives me headaches:

here entities:

public class message {     public int messageid { get; set; }     public string name { get; set; }             public list<messagepart> messageparts { get; set; } } public class messagepart {     public int messagepartid { get; set; }     public string text { get; set; }             public int messageid { get; set; }     public message message { get; set; } } 

createmessage() supposed to:

static void createmessages()     {         using (var db = new testcontext())         {             var m1 = new message             {                 name = "train_arrives_in_x_minutes",                                     messageparts = new list<messagepart>()                 {                     new messagepart {                         text = "train arrives in 5 minutes"                                                 },                     new messagepart {                         text = "zug faehrt in 5 minuten ein",                                                 }                 }             };             var m2 = new message             {                 name = "train_out_of_service",                 messageparts = new list<messagepart>()                 {                     new messagepart {                         text = "train out of service"                                                 },                     new messagepart {                         text = "kein service auf dieser strecke",                                                 }                 }             };              db.messages.add(m1);             db.messages.add(m2);              var count = db.savechanges();             console.writeline("{0} records saved database", count);          }     } 

reading existing database reads master record fine, detail recordset pointer stays null.

static void readmessages()     {         using (var db = new testcontext())         {             foreach (message m in db.messages)             {                 console.writeline(m.name);                 // exception here: m.messageparts null                 foreach(messagepart mp in m.messageparts)                 {                     console.writeline("mp.text={0}", mp.text);                 }                                 }                         }     } 

is there can force messagesparts load? i've worked other (python) orms before , never had problem before. problem lazy loading? tried fetch childrecords using linq statement, didn't either. looks in database though.

if want enable lazyloading need enable lazyloading (should enabled default) , make property virtual:

public testcontext()      : base(name = "conntextionname") {     this.configuration.proxycreationenabled = true;     this.configuration.lazyloadingenabled = true; } 

and models shuodl like:

public class message {     public int messageid { get; set; }     public string name { get; set; }             public virtual icollection<messagepart> messageparts { get; set; } } public class messagepart {     public int messagepartid { get; set; }     public string text { get; set; }             public int messageid { get; set; }     public virtual message message { get; set; } } 

if not want use lazyloading, can load related entities using eager loading:

using system.data.entity;  using (var db = new testcontext()) {     int messageid = ....;     message message = db.messages         .where(m => m.messageid == messageid)         .include(m => m.messageparts) // eagerly load message parts         .firstordefault();      // message , related message parts loaded , ready. } 

for more information, please have @ this site.