C#•2y ago

✅ Dapper InsertAsync fails on Postgres with relation does not exist

Hello, I am currently trying to run Dapper CRUD operations (Dapper.Contrib.Extensions) on a database table with the name "Permissions", when I try to run InsertAsync, I get a relation "permissions" does not exist. I've been skimming the interwebs, but I can't seem to find a solution. It seems like Dapper is not double quoting the tablename, even though the database model is annotated with [Table("Permissions")]

14 Replies

notlyze•2y ago

@AtomicLiquid It is possible that there is a case sensitivity issue with the table name. In PostgreSQL, table names are case-sensitive by default. This means that if the table is created with uppercase characters in its name, you will need to specify the name with the correct case when you execute queries against it. To fix this issue, you can try specifying the table name in double quotes in the [Table] attribute. For example:

[Table("\"Permissions\"")]

[Table("\"Permissions\"")]

This should instruct Dapper to use the exact case of the table name as specified in the attribute when generating the SQL query. Alternatively, you can also set the default case sensitivity behavior for table names in PostgreSQL by setting the "quote_ident" option in the postgresql.conf configuration file. This option controls whether or not PostgreSQL will treat unquoted identifiers as case-sensitive. For example, to make table names case-insensitive by default, you can add the following line to your postgresql.conf file:

quote_ident = off

quote_ident = off

This will cause PostgreSQL to treat all unquoted identifiers as case-insensitive, so you won't need to use double quotes around the table name in your [Table] attribute. However, keep in mind that this may affect the case sensitivity of other identifiers in your database, so you should use this option with caution.

AtomicLiquid•2y ago

You're a champ! Thanks alot for the reply.

notlyze•2y ago

You're welcome! I'm glad that I could help. If you have any other questions or need further assistance, don't hesitate to ask.

AtomicLiquid•2y ago

Not sure if this is your expertise, but how would I go about creating Dapper queries that will work for several different database types, such as MSSQL, SQLite, MySQL etc? What do I have to keep in mind?

notlyze•2y ago

Dapper is a micro-ORM (Object-Relational Mapping) that is designed to be database agnostic, which means that it can be used to execute queries and map the results to .NET objects regardless of the underlying database engine. This means that you can write Dapper queries that will work with multiple database types as long as you follow a few guidelines. Here are some tips for writing Dapper queries that will work with multiple database types:

1:
Use parameterized queries: Dapper supports the use of named or unnamed parameters in your queries. Using parameters helps to prevent SQL injection attacks and can also improve performance by allowing the database engine to cache the query plan.

2:
Use standard SQL: Dapper supports most standard SQL syntax, so you should try to use standard SQL statements and functions in your queries whenever possible. This will help to ensure that your queries will work with multiple database types.

3:
Use database-agnostic functions: Some functions, such as COUNT(), AVG(), and SUM(), are supported by most database engines. Using these functions can help to make your queries more portable across different database types.

4:
Use database-specific features sparingly: If you need to use a database-specific feature in your query, you should try to isolate it as much as possible to make it easier to port your query to other database types. For example, you can use a case statement or a function to encapsulate the database-specific logic.

1:
Use parameterized queries: Dapper supports the use of named or unnamed parameters in your queries. Using parameters helps to prevent SQL injection attacks and can also improve performance by allowing the database engine to cache the query plan.

2:
Use standard SQL: Dapper supports most standard SQL syntax, so you should try to use standard SQL statements and functions in your queries whenever possible. This will help to ensure that your queries will work with multiple database types.

3:
Use database-agnostic functions: Some functions, such as COUNT(), AVG(), and SUM(), are supported by most database engines. Using these functions can help to make your queries more portable across different database types.

4:
Use database-specific features sparingly: If you need to use a database-specific feature in your query, you should try to isolate it as much as possible to make it easier to port your query to other database types. For example, you can use a case statement or a function to encapsulate the database-specific logic.

By following these guidelines, you should be able to write Dapper queries that will work with multiple database types. However, keep in mind that there may still be some differences between database engines that you need to account for, such as data types, functions, and indexing options. @AtomicLiquid

AtomicLiquid•2y ago

Yep, definitely is sort of a dangerous road to tread... Over to the original issue again, I am now facing an issue with the CRUD operations from Dapper again, is that it seems that I have to add the Column annotation for every single field within the database model, because it defaults to lowercase. We're creating a tool that will be used by several different server admins, and it's open-source. This makes the solution of adding the quote_ident setting to the conf file a bit tedious for the users using our tool. Does this mean we should consider using camelCase throughout the tables and fields instead of capitalizing the first letter? Or is there another way?

notlyze•2y ago

It is generally a good practice to use consistent naming conventions for your database objects, such as tables and columns, to make them easier to work with. One option you could consider is using camelCase for your database objects, as you mentioned. This is a common naming convention in the .NET ecosystem, and it can help to avoid issues with case sensitivity when working with databases. If you choose to use camelCase for your database objects, you can use the [Column] attribute to specify the exact case of the column name as it appears in the database. For example:

[Column("columnName")]
public string ColumnName { get; set; }

[Column("columnName")]
public string ColumnName { get; set; }

This will instruct Dapper to use the exact case of the column name as specified in the attribute when generating the SQL query. Alternatively, you can also use the [Table] and [Column] attributes to specify the names of your database objects in all uppercase or all lowercase, depending on your preference. For example:

[Table("PERMISSIONS")]
public class Permission
{
    [Column("ID")]
    public int Id { get; set; }

    [Column("NAME")]
    public string Name { get; set; }
}

[Table("PERMISSIONS")]
public class Permission
{
    [Column("ID")]
    public int Id { get; set; }

    [Column("NAME")]
    public string Name { get; set; }
}

Using a consistent naming convention and specifying the exact case of your database objects using the [Table] and [Column] attributes should help to avoid issues with case sensitivity when working with Dapper.

AtomicLiquid•2y ago

Yeah, definitely seems like there's trade-offs no matter how I decide to name the tables. If I decide to not add the column annotation and rename all tables and fields to camel case, I will still face the same problems when I change back to using a MySQL database... Seems like using the [Column] annotation is the way to go then. Thanks a lot for the well detailed answers, it's really appreciated!

notlyze•2y ago

You're welcome! I'm glad that I could help. Using the [Column] attribute to specify the exact case of your database objects is generally the recommended approach when working with Dapper. This will help to ensure that your queries are executed correctly and that the results are mapped to the correct properties in your .NET objects, regardless of the underlying database engine. Using a consistent naming convention, such as camelCase, can also make your code easier to read and maintain. However, keep in mind that you may still need to consider the case sensitivity of your database objects when switching between different database engines. Some database engines, such as MySQL, are case-insensitive by default, while others, such as PostgreSQL, are case-sensitive. If you do decide to use camelCase for your database objects, you may want to consider adding a configuration option to your tool that allows users to specify the case sensitivity of their database. This will give users the flexibility to choose the naming convention that works best for them and their database environment.

AtomicLiquid•2y ago

Interesting! How would you implement such a feature though?

notlyze•2y ago

There are a few different ways you could implement a configuration option to allow users to specify the case sensitivity of their database. Here are a couple of options:

1:
Use a configuration file: You can create a configuration file that users can edit to specify the case sensitivity of their database. For example, you could create an appsettings.json file that contains a setting for the case sensitivity of the database. Users could then edit the file to specify whether the database is case-sensitive or case-insensitive.

2:
Use a command-line argument: You can also allow users to specify the case sensitivity of their database using a command-line argument when starting your tool. For example, you could use the following syntax:

1:
Use a configuration file: You can create a configuration file that users can edit to specify the case sensitivity of their database. For example, you could create an appsettings.json file that contains a setting for the case sensitivity of the database. Users could then edit the file to specify whether the database is case-sensitive or case-insensitive.

2:
Use a command-line argument: You can also allow users to specify the case sensitivity of their database using a command-line argument when starting your tool. For example, you could use the following syntax:

mytool.exe --case-sensitive

mytool.exe --case-sensitive

3:
Use a configuration API: If your tool is a .NET application, you can also use the .NET Configuration API to allow users to specify the case sensitivity of their database. This API provides a flexible way to read and write configuration data from various sources, such as configuration files, environment variables, and command-line arguments.

3:
Use a configuration API: If your tool is a .NET application, you can also use the .NET Configuration API to allow users to specify the case sensitivity of their database. This API provides a flexible way to read and write configuration data from various sources, such as configuration files, environment variables, and command-line arguments.

Regardless of the approach you choose, you will need to update your code to use the case sensitivity setting when generating Dapper queries. You can use the [Table] and [Column] attributes to specify the exact case of your database objects based on the case sensitivity setting.

AtomicLiquid•2y ago

Thanks again!

notlyze•2y ago

<a:CH_ShiroPat:970610996425142342> Good luck with your project!

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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✅ Dapper InsertAsync fails on Postgres with relation does not exist