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Message "There is already an open DataReader associated with this Connection which must be closed first." string

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Mark Smith answered on May 19, 2021 Popularity 8/10 Helpfulness 4/10

answer Message "There is already an open DataReader associated with this Connection which must be closed first." string

related There is already an open DataReader associated with this Command which must be closed first.

related There is already an open DataReader associated with this Connection which must be closed first.

related There is already an open DataReader associated with this Command which must be closed first.

Message "There is already an open DataReader associated with this Connection which must be closed first." string

Comment

// You need to call .ToList() on your IQueryable to close the DataReader
// before you can use the DbContext again.

var list = new List<Baz>;

var results = _db.Foo.Where(f => f.Id > 69); // DataReader stays open.
// var results = _db.Foo.Where(f => f.Id > 69).ToList(); // DataReader closed.

foreach (var r in results)
{
  list.Add(new Bar(r.Name, _db));
}

// --- Elsewhere: 
  
class Bar {
	public Bar(string name, dbContext _db)
    {
      var moreResults = _db.Bar.Where(b => b.Id < 420); // ERROR
      
    }
  ...
}

Popularity 8/10 Helpfulness 4/10 Language csharp

Source: Grepper

Tags: c# connection datareader message string this

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Contributed on Jan 26 2023

Mark Smith

0 Answers Avg Quality 2/10

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There is already an open DataReader associated with this Command which must be closed first.

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Add this to your connection string:
MultipleActiveResultSets=true;

Popularity 10/10 Helpfulness 9/10 Language whatever

Source: Grepper

Tags: command

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Contributed on May 19 2021

Drab Dogfish

0 Answers Avg Quality 2/10

There is already an open DataReader associated with this Connection which must be closed first.

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Add this to your connection string:
MultipleActiveResultSets=true;

Popularity 9/10 Helpfulness 6/10 Language whatever

Source: Grepper

Tags: connection c

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Contributed on Jan 11 2023

steve muland

0 Answers Avg Quality 2/10

There is already an open DataReader associated with this Command which must be closed first.

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This can happen if you execute a query while iterating over the results from another query. It is not clear from your example where this happens because the example is not complete.

One thing that can cause this is lazy loading triggered when iterating over the results of some query.

This can be easily solved by allowing MARS in your connection string. Add MultipleActiveResultSets=true to the provider part of your connection string (where Data Source, Initial Catalog, etc. are specified).

Popularity 9/10 Helpfulness 2/10 Language whatever

Source: stackoverflow.com

Tags: command

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Contributed on Aug 16 2022

Pavel Dinh

0 Answers Avg Quality 2/10

Message "There is already an open DataReader associated with this Connection which must be closed first." string

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Message "There is already an open DataReader associated with this Connection which must be closed first." string

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There is already an open DataReader associated with this Command which must be closed first.

There is already an open DataReader associated with this Connection which must be closed first.

There is already an open DataReader associated with this Command which must be closed first.

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