Ignore a property in AutoMapper?

Question

I'm using Automapper to copy one object properties to other and later will update in database using EF.

Question is how to tell Automapper copy every property but ignore a particular property (in this case it will be Id). I'm new to AutoMapper and just have done this code. I don't have other configurations or use of AutoMap in project.

Mapper.Map(lead, existingLead);

I have downloaded AutoMapper form here https://github.com/AutoMapper/AutoMapper

possible duplicate of [automapper how to ignore property in source item that does not exist in destination](http://stackoverflow.com/questions/4052579/automapper-how-to-ignore-property-in-source-item-that-does-not-exist-in-destinat) — Shiva, Nov 12 '14 at 23:15

score 25 · Accepted Answer · edited Jan 27 '20 at 23:58

25

On your Mapper.CreateMap<Type1, Type2>() you can use either

.ForSourceMember(x => x.Id, opt => opt.Ignore())

or

.ForMember(x => x.Id, opt => opt.Ignore())

UPDATE: It seems like .Ignore() is renamed to .DoNotValidate() according to the AutoMapper docs.

edited Jan 27 '20 at 23:58

Lina Sie

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5

answered Nov 12 '14 at 23:13

John

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sorry where I can find Mapper.CreateMap ? I just have installed in using Nuget packages and the line of code I added in question is only line I did. – user576510 Nov 12 '14 at 23:19
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@user576510 It should just be under the AutoMapper namespace. Just create that on its own line (followed by .ForMember() or .ForSourceMember() depending on how you are binding) and you should be good to go :) – John Nov 12 '14 at 23:26
@John Why I need to use `Ignore`? Properties which are missing in a destination type will get their default value. – Joseph Katzman Mar 03 '17 at 15:29
@JosephKatzman I dunno maybe its changed in the last 2 years ;) – John Mar 04 '17 at 06:45
@JosephKatzman: opt.Ignore() tells AutoMapper to not map a value to that destination member. AutoMapper maps to destination members by default so, if there is no destination member, the member doesn't get mapped anyway (and should generate a compiler error). If the destination does contain the member, AutoMapper tries to find a source member to map from, unless you use Ignore(). – Suncat2000 May 14 '20 at 13:20

score 1 · Answer 2 · answered Nov 12 '14 at 23:20

1

I use this extension method:

public static IMappingExpression<TSource, TDestination> IgnoreMember<TSource, TDestination>(
    this IMappingExpression<TSource, TDestination> map, Expression<Func<TDestination, object>> selector)
{
    map.ForMember(selector, config => config.Ignore());
    return map;
}

and I use it like this

Mapper.CreateMap<MyType1, MyType2>().IgnoreMember(m => m.PropertyName);

Hope that helps.

answered Nov 12 '14 at 23:20

Omar.Alani

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thanks, I m new to automapper, do i need add some configurations in config file ? I only have done line of code which I mention in qeustion. Wehre I should use Mapper.CreateMap ? – user576510 Nov 12 '14 at 23:24
When your app initializes, you need to call a Initialize method that will setup all the mappings of your classes. See this guide to know more Automapper https://github.com/AutoMapper/AutoMapper/wiki/Getting-started. – Omar.Alani Nov 12 '14 at 23:26

Ignore a property in AutoMapper?

2 Answers2