I just ran into trouble because I was using the .IsNullable property on a field that is coming from a view, but it is imported into the project as an entity (based on a typed view).

I did some reading about this topic here: http://www.llblgen.com/tinyforum/Messages.aspx?ThreadID=16282

The problem is though that if I develop logic that is based on an EntityField2 (and no knowledge - at least for now) from "where this field comes" (a table or a view) since the entity can be based on both, how do I know whether I can trust the .IsNullable property?

Is v3.0 supposed to handle this stuff differently?

the problem is sqlserver, (and other db's as well, though sqlserver mainly) which doesn't update meta-data of a view when the tables in the view change.

In v3 we indeed obtain the meta-data as-is from the db and with nullability. Does that help? no. the thing is that if a field in a table is changed to be nullable, the view(s) the field is in won't be updated, at least not in the sqlserver meta-data.

I know that SQLServer is trouble! Nevertheless some people are not asked and have to work with it.

What I'm trying to understand is how (or whether) I can use the .IsNullable property at all.

Since I don't know whether it is "coming from" a view or a table, how do I know whether I can trust it or not? Remember that I use LGP entities based on typed views too.

Also, why does LGP set the .IsNullable property to false for all columns of an entity based on a view? Why not "just" say it is unknown = null?

magic wrote:

I know that SQLServer is trouble! Nevertheless some people are not asked and have to work with it.

That's the way it is unfortunately

magic wrote:

What I'm trying to understand is how (or whether) I can use the .IsNullable property at all.

Since I don't know whether it is "coming from" a view or a table, how do I know whether I can trust it or not? Remember that I use LGP entities based on typed views too.

So, in short, you want to know whether an "entity" is based on a "table" or on a "view" to know if you can trust in IsNullable property. Well, AFAIK you can't. However you could add a custom property to each "entity based on a view" to flag it, then you could access that property (using the CustomPropertiesOfType entity's property) and know if you can trust on it.

magic wrote:

Also, why does LGP set the .IsNullable property to false for all columns of an entity based on a view? Why not "just" say it is unknown = null?

SqlServer doesn't update the nullability state of a view field when the nullability of a table field changes (which is in a view). This thus leads to errors, hence that piece of retrieval code is commented out the code in the driver. More info: http://llblgen.com/tinyforum/Messages.aspx?ThreadID=14825

First of all (as I already stated a couple of times), I understand that MsSQL sucks and there's not much one can do about it.

But ... why is LGP converting nullable types into not nullable? I have a view that has a nullable boolean field. The value of this field in a particular row is NULL, but when I try to access the value through the LGP entity, it is FALSE. This totally falsifies my data! LGP does the same for numeric values (turns them to 0), but not with strings where the value stays NULL.

If no assumptions can be made about whether a field is nullable or not, it should be nullable and not assigned a value that isn't there?

Furthermore, I have tried to read through the thread that you suggested, and I don't think I can follow. Can you please elaborate more on the idea of changing the source code in SqlServerSchemaRetriever.cs, line 1263? How am I supposed to do that?

This will be handled in v.3.0

Can you please elaborate more on the idea of changing the source code in SqlServerSchemaRetriever.cs, line 1263? How am I supposed to do that?

You should get the Drivers source code, found in the SDK package. (Download it from the website).

I think I'm really too stupid to find the download. Sorry.

Can you please provide a link or instructions? Thank you.

magic wrote:

I think I'm really too stupid to find the download. Sorry.

Can you please provide a link or instructions? Thank you.

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