41 lines
1.7 KiB
C#
41 lines
1.7 KiB
C#
using System;
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using System.Linq.Expressions;
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namespace Microsoft.AspNetCore.Mvc.ModelBinding
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{
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/// <summary>
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/// Provides extension methods for the ASP.NET Core application.
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/// </summary>
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public static class ModelStateDictionaryExtensions
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{
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/// <summary>
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/// Adds the specified <paramref name="errorMessage"/> to the <see cref="ModelStateEntry.Errors"/>
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/// instance that is associated with the key specified as a <see cref="MemberExpression"/>.
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/// </summary>
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/// <typeparam name="TModel">The type of the model.</typeparam>
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/// <typeparam name="TProperty">The type of the property.</typeparam>
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/// <param name="modelState">The <see cref="ModelStateDictionary"/> instance.</param>
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/// <param name="_">The model. Only used to infer the model type.</param>
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/// <param name="keyExpression">The <see cref="MemberExpression"/> that specifies the property.</param>
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/// <param name="errorMessage">The error message to add.</param>
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/// <exception cref="InvalidOperationException">No member expression provided.</exception>
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public static void AddModelError<TModel, TProperty>(this ModelStateDictionary modelState, TModel _, Expression<Func<TModel, TProperty>> keyExpression, string errorMessage)
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{
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if (modelState is null)
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throw new ArgumentNullException(nameof(modelState));
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string key = "";
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var expr = keyExpression.Body as MemberExpression;
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while (expr != null)
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{
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key = expr.Member.Name + (key != "" ? "." + key : "");
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expr = expr.Expression as MemberExpression;
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}
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if (key == "")
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throw new InvalidOperationException("No member expression provided.");
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modelState.AddModelError(key, errorMessage);
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}
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}
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}
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