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InvalidCastException when querying MySql database with Dapper [closed]

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0

I'm using Dapper to query MySQL database from Linux server.

For my first query, really simple, I use this code:

public async Task<Customer> GetCustomerByCode(string customerCode)

 using (var connection = GetOpenConnection())
 
 Customer result = await connection.ExecuteScalarAsync<Customer>("select * from `Customer` where `Code` = @customerCode", new customerCode , null, null, System.Data.CommandType.Text);
 return result;
 


protected IDbConnection GetOpenConnection()

 var connection = new MySqlConnection(connectionString);
 connection.Open();

 return connection;


Trying to execute this query with an user code (existing) `PGM` I get this error:

System.InvalidCastException: Invalid cast from 'System.Int32' to 'EmemoriesSuite.Data.Entities.Customer'.

I'm not really understanding what I am doing wrong.. This should be my result query, and using it in PhpMyAdmin works like charme (select * from Customer where Code = 'PGM')

c# mysql dapper

share|improve this question

edited Mar 23 at 17:57

Pier Giorgio Misley

asked Mar 23 at 17:41

Pier Giorgio MisleyPier Giorgio Misley

3,71821643

closed as off-topic by Ian Kemp, Dmitry, thewaywewere, Sterling Archer, Amit Joshi Mar 25 at 6:02

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question was caused by a problem that can no longer be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting the shortest program necessary to reproduce the problem before posting." – Ian Kemp, Dmitry, thewaywewere, Sterling Archer, Amit Joshi

If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  don't use ExecuteScalar
  
  – Daniel A. White
  Mar 23 at 17:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @DanielA.White Hi, thanks for the hint! just to know, why shouldn't I use it? and what should I use instead?
  
  – Pier Giorgio Misley
  Mar 23 at 18:04
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  ExecuteScalar is used when you need a single object a string or an int from the database. What you need instead is connection.Query() this will return a resultset which can then be converted to object. What I also guess is you may need to use connection.Query().First()
  
  – Priyank Panchal
  Mar 23 at 18:05
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  oh, I didn't know that at all, thanks! @PriyankPanchal I'll give it a try
  
  – Pier Giorgio Misley
  Mar 23 at 18:06
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @PriyankPanchal it works! thanks! if you post an answer I will accept it
  
  – Pier Giorgio Misley
  Mar 24 at 10:49
  

  
  
  
  

 | 
show 1 more comment

0

I'm using Dapper to query MySQL database from Linux server.

For my first query, really simple, I use this code:

public async Task<Customer> GetCustomerByCode(string customerCode)

 using (var connection = GetOpenConnection())
 
 Customer result = await connection.ExecuteScalarAsync<Customer>("select * from `Customer` where `Code` = @customerCode", new customerCode , null, null, System.Data.CommandType.Text);
 return result;
 


protected IDbConnection GetOpenConnection()

 var connection = new MySqlConnection(connectionString);
 connection.Open();

 return connection;


Trying to execute this query with an user code (existing) `PGM` I get this error:

System.InvalidCastException: Invalid cast from 'System.Int32' to 'EmemoriesSuite.Data.Entities.Customer'.

I'm not really understanding what I am doing wrong.. This should be my result query, and using it in PhpMyAdmin works like charme (select * from Customer where Code = 'PGM')

c# mysql dapper

share|improve this question

edited Mar 23 at 17:57

Pier Giorgio Misley

asked Mar 23 at 17:41

Pier Giorgio MisleyPier Giorgio Misley

3,71821643

closed as off-topic by Ian Kemp, Dmitry, thewaywewere, Sterling Archer, Amit Joshi Mar 25 at 6:02

This question appears to be off-topic. The users who voted to close gave this specific reason:

• "This question was caused by a problem that can no longer be reproduced or a simple typographical error. While similar questions may be on-topic here, this one was resolved in a manner unlikely to help future readers. This can often be avoided by identifying and closely inspecting the shortest program necessary to reproduce the problem before posting." – Ian Kemp, Dmitry, thewaywewere, Sterling Archer, Amit Joshi

If this question can be reworded to fit the rules in the help center, please edit the question.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  don't use ExecuteScalar
  
  – Daniel A. White
  Mar 23 at 17:58
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @DanielA.White Hi, thanks for the hint! just to know, why shouldn't I use it? and what should I use instead?
  
  – Pier Giorgio Misley
  Mar 23 at 18:04
  

  
  
  
  


• 
  
  
  

  
  3
  

  
  
  
  
  
  

  
  
  ExecuteScalar is used when you need a single object a string or an int from the database. What you need instead is connection.Query() this will return a resultset which can then be converted to object. What I also guess is you may need to use connection.Query().First()
  
  – Priyank Panchal
  Mar 23 at 18:05
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  oh, I didn't know that at all, thanks! @PriyankPanchal I'll give it a try
  
  – Pier Giorgio Misley
  Mar 23 at 18:06
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @PriyankPanchal it works! thanks! if you post an answer I will accept it
  
  – Pier Giorgio Misley
  Mar 24 at 10:49
  

  
  
  
  

 | 
show 1 more comment

I'm using Dapper to query MySQL database from Linux server.

For my first query, really simple, I use this code:

public async Task<Customer> GetCustomerByCode(string customerCode)

 using (var connection = GetOpenConnection())
 
 Customer result = await connection.ExecuteScalarAsync<Customer>("select * from `Customer` where `Code` = @customerCode", new customerCode , null, null, System.Data.CommandType.Text);
 return result;
 


protected IDbConnection GetOpenConnection()

 var connection = new MySqlConnection(connectionString);
 connection.Open();

 return connection;


Trying to execute this query with an user code (existing) `PGM` I get this error:

System.InvalidCastException: Invalid cast from 'System.Int32' to 'EmemoriesSuite.Data.Entities.Customer'.

I'm not really understanding what I am doing wrong.. This should be my result query, and using it in PhpMyAdmin works like charme (select * from Customer where Code = 'PGM')

c# mysql dapper

share|improve this question

edited Mar 23 at 17:57

Pier Giorgio Misley

asked Mar 23 at 17:41

Pier Giorgio MisleyPier Giorgio Misley

3,71821643

public async Task<Customer> GetCustomerByCode(string customerCode)

 using (var connection = GetOpenConnection())
 
 Customer result = await connection.ExecuteScalarAsync<Customer>("select * from `Customer` where `Code` = @customerCode", new customerCode , null, null, System.Data.CommandType.Text);
 return result;
 


protected IDbConnection GetOpenConnection()

 var connection = new MySqlConnection(connectionString);
 connection.Open();

 return connection;


Trying to execute this query with an user code (existing) `PGM` I get this error:

share|improve this question

edited Mar 23 at 17:57

Pier Giorgio Misley

asked Mar 23 at 17:41

Pier Giorgio MisleyPier Giorgio Misley

3,71821643

share|improve this question

edited Mar 23 at 17:57

Pier Giorgio Misley

asked Mar 23 at 17:41

Pier Giorgio MisleyPier Giorgio Misley

3,71821643

asked Mar 23 at 17:41

Pier Giorgio MisleyPier Giorgio Misley

3,71821643

asked Mar 23 at 17:41

Pier Giorgio MisleyPier Giorgio Misley

3,71821643

1 Answer
1

active

oldest

votes

1

ExecuteScalar is used to get a single value from the database. Instead, what you need is connection.Query() which will return a resultset. Now, because you are expecting your query to return a single record you can use connection.QuerySingle(). So kindly use the code below.

Customer result = await connection.QuerySingle<Customer>("select * from `Customer` where `Code` = @customerCode", new customerCode , null, null, System.Data.CommandType.Text);

I have not tried it in practice, but I am very sure the above will work for you.

share|improve this answer

answered Mar 24 at 11:36

Priyank PanchalPriyank Panchal

7241714

add a comment | 

1

ExecuteScalar is used to get a single value from the database. Instead, what you need is connection.Query() which will return a resultset. Now, because you are expecting your query to return a single record you can use connection.QuerySingle(). So kindly use the code below.

Customer result = await connection.QuerySingle<Customer>("select * from `Customer` where `Code` = @customerCode", new customerCode , null, null, System.Data.CommandType.Text);

I have not tried it in practice, but I am very sure the above will work for you.

share|improve this answer

answered Mar 24 at 11:36

Priyank PanchalPriyank Panchal

7241714

add a comment | 

1

ExecuteScalar is used to get a single value from the database. Instead, what you need is connection.Query() which will return a resultset. Now, because you are expecting your query to return a single record you can use connection.QuerySingle(). So kindly use the code below.

Customer result = await connection.QuerySingle<Customer>("select * from `Customer` where `Code` = @customerCode", new customerCode , null, null, System.Data.CommandType.Text);

I have not tried it in practice, but I am very sure the above will work for you.

share|improve this answer

answered Mar 24 at 11:36

Priyank PanchalPriyank Panchal

7241714

add a comment | 

ExecuteScalar is used to get a single value from the database. Instead, what you need is connection.Query() which will return a resultset. Now, because you are expecting your query to return a single record you can use connection.QuerySingle(). So kindly use the code below.

Customer result = await connection.QuerySingle<Customer>("select * from `Customer` where `Code` = @customerCode", new customerCode , null, null, System.Data.CommandType.Text);

I have not tried it in practice, but I am very sure the above will work for you.

share|improve this answer

answered Mar 24 at 11:36

Priyank PanchalPriyank Panchal

7241714

Customer result = await connection.QuerySingle<Customer>("select * from `Customer` where `Code` = @customerCode", new customerCode , null, null, System.Data.CommandType.Text);

share|improve this answer

answered Mar 24 at 11:36

Priyank PanchalPriyank Panchal

7241714

answered Mar 24 at 11:36

Priyank PanchalPriyank Panchal

7241714

answered Mar 24 at 11:36

Priyank PanchalPriyank Panchal

7241714