119 lines
4.5 KiB
C#
119 lines
4.5 KiB
C#
using System.Linq.Expressions;
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using MaksIT.Core.Abstractions.Webapi;
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namespace MaksIT.Core.Webapi.Models;
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public class PagedRequest : RequestModelBase {
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public int PageSize { get; set; } = 100;
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public int PageNumber { get; set; } = 1;
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// Global filter applicable to any collection
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public string? Filters { get; set; }
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// Specific filters for different collections
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public Dictionary<string, string>? CollectionFilters { get; set; }
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// Optional sorting
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public string? SortBy { get; set; }
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public bool IsAscending { get; set; } = true;
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// Method to build an expression for a specific collection, combining global and collection-specific filters
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public Expression<Func<T, bool>> BuildCollectionFilterExpression<T>(string collectionName) {
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var expressions = new List<Expression>();
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var parameter = Expression.Parameter(typeof(T), "x");
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// Add global filters if available
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if (!string.IsNullOrEmpty(Filters)) {
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var globalFilterExpression = BuildFilterExpression<T>(Filters, parameter);
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expressions.Add(globalFilterExpression);
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}
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// Add collection-specific filters if available
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if (CollectionFilters != null && CollectionFilters.ContainsKey(collectionName) && !string.IsNullOrEmpty(CollectionFilters[collectionName])) {
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var collectionFilterExpression = BuildFilterExpression<T>(CollectionFilters[collectionName], parameter);
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expressions.Add(collectionFilterExpression);
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}
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// Combine the expressions using AND (you can extend to OR logic if needed)
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Expression combinedExpression;
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if (expressions.Any()) {
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combinedExpression = expressions.Aggregate(Expression.AndAlso);
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}
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else {
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// Default to 'true' if no filters are provided
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combinedExpression = Expression.Constant(true);
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}
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return Expression.Lambda<Func<T, bool>>(combinedExpression, parameter);
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}
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// Method to build a LINQ expression from a single filter string (global or collection-specific)
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public Expression<Func<T, bool>> BuildFilterExpression<T>(string filter, ParameterExpression? parameter = null) {
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if (string.IsNullOrEmpty(filter))
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return x => true; // Default to 'true' if no filters are provided
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parameter ??= Expression.Parameter(typeof(T), "x");
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var expressions = new List<Expression>();
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// Parse the filters string (this logic can be extended to support more complex filtering)
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var filters = filter.Split(new[] { "AND", "OR" }, StringSplitOptions.None);
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foreach (var subFilter in filters) {
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if (subFilter.Contains('=')) {
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var parts = subFilter.Split('=');
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var propertyName = parts[0].Trim();
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var value = parts[1].Trim().Replace("'", "");
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var property = Expression.Property(parameter, propertyName);
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var constant = Expression.Constant(ConvertValue(property.Type, value));
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expressions.Add(Expression.Equal(property, constant));
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}
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else if (subFilter.Contains('>') || subFilter.Contains('<')) {
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var comparisonType = subFilter.Contains(">=") ? ">=" :
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subFilter.Contains("<=") ? "<=" :
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subFilter.Contains(">") ? ">" : "<";
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var parts = subFilter.Split(new[] { '>', '<', '=', ' ' }, StringSplitOptions.RemoveEmptyEntries);
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var propertyName = parts[0].Trim();
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var value = parts[1].Trim().Replace("'", "");
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var property = Expression.Property(parameter, propertyName);
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var constant = Expression.Constant(ConvertValue(property.Type, value));
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switch (comparisonType) {
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case ">":
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expressions.Add(Expression.GreaterThan(property, constant));
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break;
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case "<":
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expressions.Add(Expression.LessThan(property, constant));
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break;
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case ">=":
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expressions.Add(Expression.GreaterThanOrEqual(property, constant));
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break;
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case "<=":
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expressions.Add(Expression.LessThanOrEqual(property, constant));
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break;
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}
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}
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}
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// Combine the expressions using AND (you can extend to support OR)
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var combinedExpression = expressions.Aggregate(Expression.AndAlso);
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return Expression.Lambda<Func<T, bool>>(combinedExpression, parameter);
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}
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// Helper method to convert the value to the correct type
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private static object ConvertValue(Type type, string value) {
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if (type == typeof(int))
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return int.Parse(value);
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if (type == typeof(bool))
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return bool.Parse(value);
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if (type == typeof(DateTime))
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return DateTime.Parse(value);
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return value; // Default to string
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}
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}
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