1 files changed, 188 insertions, 0 deletions
diff --git a/dropped/docker/crupest-api/CrupestApi/CrupestApi.Commons/Crud/ColumnMetadata.cs b/dropped/docker/crupest-api/CrupestApi/CrupestApi.Commons/Crud/ColumnMetadata.cs
new file mode 100644
index 0000000..7247ff1
--- /dev/null
+++ b/dropped/docker/crupest-api/CrupestApi/CrupestApi.Commons/Crud/ColumnMetadata.cs
@@ -0,0 +1,188 @@
+namespace CrupestApi.Commons.Crud;
+
+public static class ColumnMetadataKeys
+{
+    public const string ColumnName = nameof(ColumnAttribute.ColumnName);
+    public const string NotNull = nameof(ColumnAttribute.NotNull);
+    public const string IsPrimaryKey = nameof(ColumnAttribute.IsPrimaryKey);
+    public const string Index = nameof(ColumnAttribute.Index);
+
+    /// <summary>
+    /// This will add hooks for string type column to coerce null to ""(empty string) when get or set. No effect on non-string type.
+    /// </summary> 
+    public const string DefaultEmptyForString = nameof(ColumnAttribute.DefaultEmptyForString);
+
+    /// <summary>
+    /// This indicates that you take care of generate this column value when create entity. User calling the api can not specify the value.
+    /// </summary>
+    public const string OnlyGenerated = nameof(ColumnAttribute.OnlyGenerated);
+
+    /// <summary>
+    /// The default value generator method name in entity type. Default to null, aka, search for ColumnNameDefaultValueGenerator. 
+    /// Generator has signature <code>static void DefaultValueGenerator(ColumnInfo column)</code>
+    /// </summary>
+    public const string DefaultValueGenerator = nameof(ColumnAttribute.DefaultValueGenerator);
+
+    /// <summary>
+    /// The validator method name in entity type. Default to null, aka, the default validator.
+    /// Validator has signature <code>static void Validator(ColumnInfo column, object value)</code>
+    /// Value param is never null. If you want to mean NULL, it should be a <see cref="DbNullValue"/>.
+    /// </summary>
+    public const string Validator = nameof(ColumnAttribute.Validator);
+
+    /// <summary>
+    /// The column can only be set when inserted, can't be changed in update.
+    /// </summary>
+    /// <returns></returns>
+    public const string NoUpdate = nameof(ColumnAttribute.NoUpdate);
+
+    /// <summary>
+    /// This column acts as key when get one entity for http get method in path. 
+    /// </summary>
+    public const string ActAsKey = nameof(ColumnAttribute.ActAsKey);
+
+    /// <summary>
+    /// The default value used for the column.
+    /// </summary>
+    public const string DefaultValue = nameof(ColumnAttribute.DefaultValue);
+}
+
+public interface IColumnMetadata
+{
+    bool TryGetValue(string key, out object? value);
+
+    object? GetValueOrDefault(string key)
+    {
+        if (TryGetValue(key, out var value))
+        {
+            return value;
+        }
+        else
+        {
+            return null;
+        }
+    }
+
+    T? GetValueOrDefault<T>(string key)
+    {
+        return (T?)GetValueOrDefault(key);
+    }
+
+    object? this[string key]
+    {
+        get
+        {
+            if (TryGetValue(key, out var value))
+            {
+                return value;
+            }
+            else
+            {
+                throw new KeyNotFoundException("Key not found.");
+            }
+        }
+    }
+}
+
+public enum ColumnIndexType
+{
+    None,
+    Unique,
+    NonUnique
+}
+
+[AttributeUsage(AttributeTargets.Property, AllowMultiple = false)]
+public class ColumnAttribute : Attribute, IColumnMetadata
+{
+    // if null, use the property name.
+    public string? ColumnName { get; init; }
+
+    // default false.
+    public bool NotNull { get; init; }
+
+    // default false
+    public bool IsPrimaryKey { get; init; }
+
+    // default None
+    public ColumnIndexType Index { get; init; } = ColumnIndexType.None;
+
+    /// <seealso cref="ColumnMetadataKeys.DefaultEmptyForString"/>
+    public bool DefaultEmptyForString { get; init; }
+
+    /// <seealso cref="ColumnMetadataKeys.OnlyGenerated"/>
+    public bool OnlyGenerated { get; init; }
+
+    /// <seealso cref="ColumnMetadataKeys.DefaultValueGenerator"/>
+    public string? DefaultValueGenerator { get; init; }
+
+    /// <seealso cref="ColumnMetadataKeys.Validator"/>
+    public string? Validator { get; init; }
+
+    /// <seealso cref="ColumnMetadataKeys.NoUpdate"/>
+    public bool NoUpdate { get; init; }
+
+    /// <seealso cref="ColumnMetadataKeys.ActAsKey"/>
+    public bool ActAsKey { get; init; }
+
+    public object? DefaultValue { get; init; }
+
+    public bool TryGetValue(string key, out object? value)
+    {
+        var property = GetType().GetProperty(key);
+        if (property is null)
+        {
+            value = null;
+            return false;
+        }
+        value = property.GetValue(this);
+        return true;
+    }
+}
+
+public class AggregateColumnMetadata : IColumnMetadata
+{
+    private IDictionary<string, object?> _own = new Dictionary<string, object?>();
+    private IList<IColumnMetadata> _children = new List<IColumnMetadata>();
+
+    public void Add(string key, object? value)
+    {
+        _own[key] = value;
+    }
+
+    public void Remove(string key)
+    {
+        _own.Remove(key);
+    }
+
+    public void Add(IColumnMetadata child)
+    {
+        _children.Add(child);
+    }
+
+    public void Remove(IColumnMetadata child)
+    {
+        _children.Remove(child);
+    }
+
+    public bool TryGetValue(string key, out object? value)
+    {
+        if (_own.ContainsKey(key))
+        {
+            value = _own[key];
+            return true;
+        }
+
+        bool found = false;
+        value = null;
+        foreach (var child in _children)
+        {
+            if (child.TryGetValue(key, out var tempValue))
+            {
+                value = tempValue;
+                found = true;
+            }
+        }
+
+        return found;
+    }
+}