Create a new record based on another with Entity

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Create a new record based on another with Entity

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#1 by (2 votes)
#2 by (0 votes)

2

I need to add some columns to a database as follows:

I keep a line of bd in a variable

 Market novo = new market();
 novo = context.Markets.where(blabla).First();

I change a column of the line

 novo.ParentID = 50;

I'm trying to get the error message:

 context.AddObject(novo); // da erro por causa da PrimaryKey

c# entity-framework

asked by anonymous 19.09.2017 / 15:07

2 answers

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score 2 · Answer 1

If you need to create a new object then you should copy the properties of the base object and do not completely assign the object, like this:

Market novo = new market();
var objAux = context.Markets.where(blabla).First();

novo.prop1 = objAux.prop1;
novo.prop2 = objAux.prop2;
novo.prop3 = objAux.prop3;
novo.prop4 = NovoValor;

context.AddObject(novo);

score 0 · Answer 2

You can also use MemberWiseClone . This method exists in the Object class but has protected access so if you can use it it can be made available in a method:

public Market Clone(){
    return base.MemberwiseClone() as Market;
}

And use as follows:

var objAux = context.Markets.where(blabla).First().Clone();

Please note that MemberwiseClone makes a copy of the integral object, ie the references to other objects are retained.