is multi mapping in dapper care about the sqlstr`s column order?

Question

is multi mapping in dapper care about the sqlstr`s column order?

dapper orm

Question

for example:

here is my pocos:

public class product
{
    public int productid { set; get; }
    public category category { set; get; }
    public string productname { set; get; }
}

also the category:

public class category
{
    public int categoryid { set; get; }
    public string categoryname { set; get; }
    public string Description { set; get; }
}

and the sqlstr:

select p.ProductID, p.ProductName, c.CategoryName, c.CategoryID,  c.Description 
from Products p inner join Categories c 
on p.CategoryID=c.CategoryID

if i choose "c.CategoryID" as splitOn. then c.CategoryName won`t be assigned, so i changed the order of column:

select p.ProductID, p.ProductName, c.CategoryID,  c.CategoryName, c.Description ...

this time everything is ok.

am i misunderstand something, any help will be ok.

thx.

pinopino

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Marc Gravell · Accepted Answer · 6/5/2013 6:51:29 AM

Actually, I suspect you need to use "CategoryID" to split on, not "c.CategoryID", as the results don't get to see the aliases (c.). But, to explain: the "split on" feature partitions a horizontal set of results into multiple pieces. For example, if we have:

Id    A    B    Id    C    D   Id    E    F

and we split on "Id", then we get:

Id    A    B         |      Id    C    D        |       Id    E    F

(note that the "split" can be multiple different column names; it does not need to be the same thing each time)

So: within each horizontal partition - no, the order doesn't matter. But: if the "split" columns are positioned such that a column (CategoryName) ends up in the wrong partition, then yes, that matters. This behavior is demanded by the fact that column names do not have to be unique - so it can't just look for CategoryName - that could be unrelated; it needs to look for CategoryName in the correct partition.

In your specific example: move the column, or simply use CategoryName as the split name (basically, it just needs to know the first column in the partition).

is multi mapping in dapper care about the sqlstr`s column order?

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