❔ Entity Framwork SQLite Add Hello, i've a little problem there. I'm trying to add something new in my database but i do not understand why it works in the case 1 and not in the case 2. case 1 : i add a new material to the database passing only the name and MaterialTypeId new Material(_viewmodel.Name, _viewmodel.MaterialType.Id) case 2: i add a new material to the database passing the name and MaterialType but there it show me the error SQL error 19 Unique Id failed new Material(_viewmodel.Name, _viewmodel.MaterialType) Have you any idea what am i doing wrond ?

help

Root Question Message

Elio12/16/2022

❔ Entity Framwork SQLite Add

Hello, i've a little problem there. I'm trying to add something new in my database but i do not understand why it works in the case 1 and not in the case 2.
case 1 :
i add a new material to the database passing only the name and MaterialTypeId
new Material(_viewmodel.Name, _viewmodel.MaterialType.Id)

case 2:
i add a new material to the database passing the name and MaterialType but there it show me the error SQL error 19 Unique Id failed
new Material(_viewmodel.Name, _viewmodel.MaterialType)

Have you any idea what am i doing wrond ?

Angius12/16/2022

Trying to add an entity that has an unattached child entity will try to create both the parent entity and the child entity

Angius12/16/2022

And since it has an ID that probably already exists, it fails

Elio12/16/2022

ohh ok so the good way to add a new material there i to fill only the materialTypeId and not the entity that's right ?

Angius12/16/2022

Yep

Elio12/16/2022

perfect i was a bit lost ahah you saved me thanks !

FusedQyou12/16/2022

You can also create the material type first, add that to the database using context.Add() and then create the material, referencing the material type you just added. EntityFramework will fill in the Id for you.

FusedQyou12/16/2022

You only need to save after adding the material. No need to do it when adding the material type

FusedQyou12/16/2022

It's a bit weird, but EntityFramework wraps your class into something it can track, so context.Add() will fix your issue because it will start tracking it.

Angius12/16/2022

Or, if you have an existing entity that's not tracked for some reason, you can force tracking with context.Attach(theThing)

Angius12/16/2022

Avoid it tho

FusedQyou12/16/2022

Yup

FusedQyou12/16/2022

But filling in the ID also works perfectly. The only drawback is that you need to save your changes first for EF to give your material type an ID at all, so this takes two saves

Elio12/16/2022

yup but it's fine to me cause i will never create a materialType and a material at the same moment so i will do it separately every time

Elio12/16/2022

thanks for the precision 🙂

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