structure app by rest api standards

add getusers
tidy up BusinessException

Azaion.Common/Extensions/EnumExtensions.cs

@@ -0,0 +1,54 @@
+using System.ComponentModel;
+using System.Reflection;
+
+namespace Azaion.Common.Extensions;
+
+/// <summary>Enum extensions</summary>
+public static class EnumExtensions
+{
+    /// <summary>Get all enums with descriptions </summary>
+    public static Dictionary<T, string> GetDescriptions<T>() where T : Enum =>
+        Enum.GetValues(typeof(T)).Cast<T>()
+            .ToDictionary(x => x, x => x.GetEnumAttrib<T, DescriptionAttribute>()?.Description ?? x.ToString());
+
+    /// <summary>
+    /// Get the Description from the DescriptionAttribute.
+    /// </summary>
+    /// <param name="enumValue"></param>
+    /// <returns></returns>
+    public static string GetDescription(this Enum enumValue)
+    {
+        return enumValue.GetType()
+            .GetMember(enumValue.ToString())
+            .First()
+            .GetCustomAttribute<DescriptionAttribute>()?
+            .Description ?? enumValue.ToString();
+    }
+
+    /// <summary> Get attribute for enum's member, usually is used for getting Description attribute </summary>
+    public static TAttrib GetEnumAttrib<T, TAttrib>(this T value) where T: Enum
+    {
+        var field = value.GetType().GetField(value.ToString());
+        if (field == null)
+            return default; 
+            
+        return field.GetCustomAttributes(typeof(TAttrib), false)
+            .Cast<TAttrib>()
+            .FirstOrDefault();   
+    }
+        
+    /// <summary>
+    /// Get default value for enum
+    /// </summary>
+    /// <typeparam name="TEnum"></typeparam>
+    /// <returns></returns>
+    public static TEnum GetDefaultValue<TEnum>() where TEnum : struct
+    {
+        var t = typeof(TEnum);
+        var attributes = (DefaultValueAttribute[])t.GetCustomAttributes(typeof(DefaultValueAttribute), false);
+        if (attributes is { Length: > 0 })
+            return (TEnum)attributes[0].Value!;
+
+        return default;
+    }
+}

Azaion.Common/Extensions/QueryableExtensions.cs

@@ -0,0 +1,27 @@
+using System.Linq.Expressions;
+
+namespace Azaion.Common.Extensions;
+
+public static class QueryableExtensions
+{
+    /// <summary>
+    /// Adds Where true predicate only if result of condition is true.
+    /// If false predicate provided, uses it in case of false result
+    /// Useful for filters, when filters should be applied only when it was set (not NULL)
+    /// </summary>
+    public static IQueryable<TSource> WhereIf<TSource>(this IQueryable<TSource> query, bool? condition,
+        Expression<Func<TSource, bool>> truePredicate,
+        Expression<Func<TSource, bool>>? falsePredicate = null)
+    {
+        if (!condition.HasValue)
+            return query;
+
+        if (condition.Value)
+            return query.Where(truePredicate);
+
+        return falsePredicate != null
+            ? query.Where(falsePredicate)
+            : query;
+    }
+
+}

Azaion.Common/Extensions/StringExtensions.cs

@@ -0,0 +1,28 @@
+using System.Text;
+
+namespace Azaion.Common.Extensions;
+
+public static class StringExtensions
+{
+    public static string ToSnakeCase(this string text)
+    {
+        if (string.IsNullOrEmpty(text))
+            return text;
+
+        if (text.Length < 2)
+            return text.ToLowerInvariant();
+
+        var sb = new StringBuilder();
+        sb.Append(char.ToLowerInvariant(text[0]));
+        for (int i = 1; i < text.Length; ++i) {
+            var c = text[i];
+            if(char.IsUpper(c)) {
+                sb.Append('_');
+                sb.Append(char.ToLowerInvariant(c));
+            } else {
+                sb.Append(c);
+            }
+        }
+        return sb.ToString();
+    }
+}