LINQ expression node 'arrayindex' is not supported in LINQ to entities.

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I am trying to do a simple select where statement to get the name of country where the code alfa2 = country[i] in a loop.

What I have tried:

C#

OFFERS_COUNTRIES c = new OFFERS_COUNTRIES();
    for (int i = 0; i < countryId.Length; i++)
       {
          var nnn = from e in db.COUNTRIES where e.alfa2 == countryId[i] select e.countryName;
          c.country_name = nnn.ToString();

          db.OFFERS_COUNTRIES.Add(c);
          db.SaveChanges();
        }

I receive the exception in this line:

c.country_name = nnn.ToString();

What is the problem?

Posted 12-Mar-18 7:20am

TempoClick

Updated 13-Mar-18 6:32am

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Comments

#realJSOP 12-Mar-18 14:44pm

BTW, your tags for this question were a little over the top. All you really needed was C#, LINQ, and Entity Framework. the rest are irrelevant to the question.

Laxmidhar tatwa technologies 12-Mar-18 22:40pm

C.country_name = nnn.first().tostring();

TempoClick 13-Mar-18 6:31am

@Laxmidhar thanks. This is what I needed.

2 solutions

Solution 1

Try this:

C#

for (int i = 0; i < countryId.Length; i++)
{
    var countryID = countryId[i]; //<-- removes array reference from the linq query
    var nnn = from e in db.COUNTRIES where e.alfa2 == countryID select e.countryName;
    c.country_name = nnn.ToString();

    db.OFFERS_COUNTRIES.Add(c);
    db.SaveChanges();
}

Posted 12-Mar-18 7:31am

#realJSOP

v2

Comments

Maciej Los 12-Mar-18 13:59pm

5ed!

TempoClick 13-Mar-18 6:30am

@JohnSimmons Thanks for the reply. This approach is missing what @Laxmidhar commented above. Without .first() it would return the SQL query instead of the variable.

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Richard Deeming · Accepted Answer · 2018-03-13T06:33:00

It would almost certainly be more efficient to retrieve the list of country names in a single query, and to only save the changes after adding all of the offers to the context:

C#

var countries = db.COUNTRIES
    .Where(e => countryId.Contains(e.alfa1))
    .Select(e => e.countryName)
    .AsEnumerable()
    .Select(name => new OFFERS_COUNTRIES 
    {
        country_name = name
    });

db.OFFERS_COUNTRIES.AddRange(countries);
db.SaveChanges();