BlazorStart/Start/Server/LinqExtensions.cs
2021-11-13 17:19:28 -08:00

48 lines
1.7 KiB
C#

using System;
using Microsoft.EntityFrameworkCore;
using System.Linq;
using System.Linq.Expressions;
namespace Start.Server {
/// <summary>Extension methods for LINQ queries</summary>
public static class LinqExtensions {
/// <summary>
/// If <paramref name="condition"/> is true, then returns <c>query.Where(expression)</c>.
/// Otherwise returns the <paramref name="query"/> unchanged.
/// </summary>
/// <param name="query">The query to potentially apply the expression to</param>
/// <param name="condition">
/// Determines whether or not the expression should be applied
/// </param>
/// <param name="expression">A function to test each element</param>
public static IQueryable<T> IfWhere<T>(this IQueryable<T> query, bool condition,
Expression<Func<T, bool>> expression) {
if (condition)
return query.Where(expression);
return query;
}
/// <summary>
/// If the <paramref name="condition"/> is true, apply the <paramref name="transform"/> to
/// the query, otherwise return the query unchanged.
/// </summary>
/// <typeparam name="T">The <paramref name="query"/>'s type</typeparam>
/// <param name="query">The query to potentially transform</param>
/// <param name="condition">
/// If true, apply the <paramref name="transform"/> to the <paramref name="query"/>
/// </param>
/// <param name="transform">
/// A function to apply to the <paramref name="query"/> if the <paramref name="condition"/>
/// is true
/// </param>
public static IQueryable<T> If<T>(this IQueryable<T> query, bool condition,
Func<IQueryable<T>, IQueryable<T>> transform) {
if (condition)
return transform(query);
return query;
}
}
}