DapperBulkQueries.Npgsql 1.8191.31429

DapperBulkQueries

Unofficial implementation for executing bulk INSERT, UPDATE and DELETE queries with Dapper for PostgreSQL.

Getting Started

Install the NuGet package

You can find the nuget package in the visual studio package manager or here.

In a Usings.cs file, add the following to enable the package:

// Add this to Usings.cs
global using DapperBulkQueries.Npgsql;
// Or add the using statement to every file where you intend to use 
using DapperBulkQueries.Npgsql;

Demo model

For the purposes of this demonstration, we will start off with the following: SQL Table:

CREATE TABLE TestTable (
    Id bigserial PRIMARY KEY,
    TextCol character varying,
    NumberCol numeric,
    BoolCol boolean);

Corresponding class:

public class TestTable
{
    public long Id { get; set; }
    public string TextCol { get; set; }
    public decimal NumberCol { get; set; }
    public bool BoolCol { get; set; }
}

I'll also assume you have a method to create and open an Npgsql connection.

Bulk Insert

// First we generate some data that we intend to insert.
// Optionally without specifying the ID as the `bigserial` datatype takes care of that.
List<TestTable> insertData = new()
{
    new() {
        TextCol = "aaa",
        NumberCol = 1.23m,
        BoolCol = true },
    new() {
        TextCol = "bbb",
        NumberCol = 4.56m,
        BoolCol = false },
    new() {
        TextCol = "ccc",
        NumberCol = 7m,
        BoolCol = true }
};

// We need to manually specify the column which we would like to insert
List<string> relevantColumns = new() { "TextCol", "NumberCol", "BoolCol" };

// Then we need to specify the name of the table we're inserting to
string tableName = "TestData";

// And finally we can execute the query like so:
NpgsqlConnection conn = await GetOpenConnection();
await conn.ExecuteBulkInsertAsync(
    tableName,
    insertData,
    relevantColumns);

Bulk Delete

// When bulk deleting we have a single selector column, 
// and anything containing any of the specified values will be deleted.
var valuesOfRowsToDelete = new List<string>() { "aaa", "ccc" };
await conn.ExecuteBulkDeleteAsync(
    tableName, 
    "TextCol", // Selector column
    valuesOfRowsToDelete);

Bulk Update

// Updated version of first and second
var updateData = new List<TestTable>()
{
    new TestTable() { 
        Id = 1, // Explicitly add ID, since we'll be filtering on this
        TextCol = "Updated first", 
        NumberCol = 5, 
        BoolCol = true },
    new TestTable() { 
        Id = 2,
        TextCol = "Updated second",
        NumberCol = 6, 
        BoolCol = false }
};

// With updating we can have multiple selectors. 
// Meaning, all selector values must match before a row is affected
// eg. Update WHERE Id AND BoolCol match
var selectors = new List<string>() { "Id", "BoolCol" };

// We also need to define which properties should be updated.
var propertiesToUpdate = new List<string>() { "TextCol", "NumberCol" };

// Finally we can execute the update like so
await conn.ExecuteBulkUpdateAsync(
    tableName,
    updateData,
    selectors,
    propertiesToUpdate
);

Calculated Properties

You may not always want the exact property value to be taken from the class.
For instance, if you have a property, which is a class containing an ID which references another table.
A solution for this is provided in this package through calculated properties.

Let's redefine our TestTable class to contain such a property

public class AnotherTable
{
    public long Id { get; set; }
    public string Name { get; set; }
}
public class TestTable
{
    public long Id { get; set; }
    public bool BoolCol { get; set; }
    
    public AnotherTable Another { get; set; }
}

To insert this we can make use of calculated properties, which take the shape of

// Dictionary key string: property name
// Function input T: in the example would be an instance of TestTable
// Function output object: the value that should be inserted in the database
Dictionary<string, Func<T, object>>

These override reading plain class properties if a property has a column name in the dictionary.
NOTE: Properties should still also be defined in the propertyNames list for it to be included.

Example usage:

List<string> relevantColumns = new() { 
    "TextCol", "NumberCol", "AnotherId" };

// Then we need to specify the name of the table we're inserting to
string tableName = "TestData";

// Define the calculated properties dictionary
Dictionary<string, Func<TestTable, object>> calculatedProperties = new()
{
    { "AnotherId", t => t.Another.Id }
};

// And finally we can execute the query like so:
NpgsqlConnection conn = await GetOpenConnection();
await conn.ExecuteBulkInsertAsync(
    tableName,
    insertData,
    relevantColumns,
    calculatedProperties);