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Add example for 'sum' custom filter function
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‎test/JsonApiDotNetCoreTests/IntegrationTests/QueryStrings/Comment.cs

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@@ -14,6 +14,9 @@ public sealed class Comment : Identifiable<int>
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[Attr]
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public DateTime CreatedAt { get; set; }
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[Attr]
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public int NumStars { get; set; }
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[HasOne]
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public WebAccount? Author { get; set; }
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‎test/JsonApiDotNetCoreTests/IntegrationTests/QueryStrings/CustomFunctions/Sum/SumExpression.cs

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using System.Text;
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using JsonApiDotNetCore;
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using JsonApiDotNetCore.Queries.Expressions;
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namespace JsonApiDotNetCoreTests.IntegrationTests.QueryStrings.CustomFunctions.Sum;
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/// <summary>
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/// Represents the "sum" function, resulting from text such as: sum(orderLines,quantity) or sum(friends,count(children))
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/// </summary>
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internal sealed class SumExpression : FunctionExpression
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{
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public const string Keyword = "sum";
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public ResourceFieldChainExpression TargetToManyRelationship { get; }
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public QueryExpression Selector { get; }
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public override Type ReturnType { get; } = typeof(ulong);
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public SumExpression(ResourceFieldChainExpression targetToManyRelationship, QueryExpression selector)
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{
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ArgumentGuard.NotNull(targetToManyRelationship);
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ArgumentGuard.NotNull(selector);
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TargetToManyRelationship = targetToManyRelationship;
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Selector = selector;
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}
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public override TResult Accept<TArgument, TResult>(QueryExpressionVisitor<TArgument, TResult> visitor, TArgument argument)
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{
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return visitor.DefaultVisit(this, argument);
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}
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public override string ToString()
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{
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return InnerToString(false);
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}
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public override string ToFullString()
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{
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return InnerToString(true);
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}
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private string InnerToString(bool toFullString)
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{
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var builder = new StringBuilder();
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builder.Append(Keyword);
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builder.Append('(');
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builder.Append(toFullString ? TargetToManyRelationship.ToFullString() : TargetToManyRelationship);
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builder.Append(',');
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builder.Append(toFullString ? Selector.ToFullString() : Selector);
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builder.Append(')');
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return builder.ToString();
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}
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public override bool Equals(object? obj)
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{
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if (ReferenceEquals(this, obj))
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{
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return true;
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}
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if (obj is null || GetType() != obj.GetType())
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{
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return false;
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}
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var other = (SumExpression)obj;
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return TargetToManyRelationship.Equals(other.TargetToManyRelationship) && Selector.Equals(other.Selector);
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}
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public override int GetHashCode()
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{
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return HashCode.Combine(TargetToManyRelationship, Selector);
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}
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}

‎test/JsonApiDotNetCoreTests/IntegrationTests/QueryStrings/CustomFunctions/Sum/SumFilterParseTests.cs

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using System.ComponentModel.Design;
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using System.Net;
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using FluentAssertions;
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using JsonApiDotNetCore.Errors;
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using JsonApiDotNetCore.Queries;
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using JsonApiDotNetCore.Queries.Expressions;
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using JsonApiDotNetCore.Queries.Parsing;
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using JsonApiDotNetCore.QueryStrings;
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using JsonApiDotNetCore.Resources;
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using JsonApiDotNetCore.Serialization.Objects;
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using JsonApiDotNetCoreTests.UnitTests.QueryStringParameters;
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using TestBuildingBlocks;
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using Xunit;
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namespace JsonApiDotNetCoreTests.IntegrationTests.QueryStrings.CustomFunctions.Sum;
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public sealed class SumFilterParseTests : BaseParseTests
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{
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private readonly FilterQueryStringParameterReader _reader;
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public SumFilterParseTests()
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{
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var resourceFactory = new ResourceFactory(new ServiceContainer());
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var scopeParser = new QueryStringParameterScopeParser();
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var valueParser = new SumFilterParser(resourceFactory);
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_reader = new FilterQueryStringParameterReader(scopeParser, valueParser, Request, ResourceGraph, Options);
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}
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[Theory]
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[InlineData("filter", "equals(sum^", "( expected.")]
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[InlineData("filter", "equals(sum(^", "To-many relationship expected.")]
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[InlineData("filter", "equals(sum(^ ", "Unexpected whitespace.")]
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[InlineData("filter", "equals(sum(^)", "To-many relationship expected.")]
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[InlineData("filter", "equals(sum(^'a')", "To-many relationship expected.")]
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[InlineData("filter", "equals(sum(^null)", "To-many relationship expected.")]
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[InlineData("filter", "equals(sum(^some)", "Field 'some' does not exist on resource type 'blogs'.")]
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[InlineData("filter", "equals(sum(^title)",
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"Field chain on resource type 'blogs' failed to match the pattern: a to-many relationship. " +
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"To-many relationship on resource type 'blogs' expected.")]
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[InlineData("filter", "equals(sum(posts^))", ", expected.")]
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[InlineData("filter", "equals(sum(posts,^))", "Field name expected.")]
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[InlineData("filter", "equals(sum(posts,author^))",
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"Field chain on resource type 'blogPosts' failed to match the pattern: zero or more to-one relationships, followed by an attribute. " +
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"To-one relationship or attribute on resource type 'webAccounts' expected.")]
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[InlineData("filter", "equals(sum(posts,^url))", "Attribute of a numeric type expected.")]
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[InlineData("filter", "equals(sum(posts,^has(labels)))", "Function that returns a numeric type expected.")]
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public void Reader_Read_Fails(string parameterName, string parameterValue, string errorMessage)
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{
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// Arrange
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var parameterValueSource = new MarkedText(parameterValue, '^');
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// Act
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Action action = () => _reader.Read(parameterName, parameterValueSource.Text);
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// Assert
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InvalidQueryStringParameterException exception = action.Should().ThrowExactly<InvalidQueryStringParameterException>().And;
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exception.ParameterName.Should().Be(parameterName);
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exception.Errors.ShouldHaveCount(1);
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ErrorObject error = exception.Errors[0];
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error.StatusCode.Should().Be(HttpStatusCode.BadRequest);
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error.Title.Should().Be("The specified filter is invalid.");
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error.Detail.Should().Be($"{errorMessage} {parameterValueSource}");
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error.Source.ShouldNotBeNull();
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error.Source.Parameter.Should().Be(parameterName);
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}
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[Theory]
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[InlineData("filter", "has(posts,greaterThan(sum(comments,numStars),'5'))", null)]
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[InlineData("filter[posts]", "equals(sum(comments,numStars),'11')", "posts")]
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[InlineData("filter[posts]", "equals(sum(labels,count(posts)),'8')", "posts")]
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public void Reader_Read_Succeeds(string parameterName, string parameterValue, string scopeExpected)
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{
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// Act
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_reader.Read(parameterName, parameterValue);
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IReadOnlyCollection<ExpressionInScope> constraints = _reader.GetConstraints();
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// Assert
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ResourceFieldChainExpression? scope = constraints.Select(expressionInScope => expressionInScope.Scope).Single();
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scope?.ToString().Should().Be(scopeExpected);
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QueryExpression value = constraints.Select(expressionInScope => expressionInScope.Expression).Single();
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value.ToString().Should().Be(parameterValue);
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}
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}

‎test/JsonApiDotNetCoreTests/IntegrationTests/QueryStrings/CustomFunctions/Sum/SumFilterParser.cs

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using JsonApiDotNetCore.Queries.Expressions;
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using JsonApiDotNetCore.Queries.Parsing;
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using JsonApiDotNetCore.QueryStrings.FieldChains;
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using JsonApiDotNetCore.Resources;
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using JsonApiDotNetCore.Resources.Annotations;
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namespace JsonApiDotNetCoreTests.IntegrationTests.QueryStrings.CustomFunctions.Sum;
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internal sealed class SumFilterParser : FilterParser
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{
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private static readonly FieldChainPattern SingleToManyRelationshipChain = FieldChainPattern.Parse("M");
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private static readonly HashSet<Type> NumericTypes = new(new[]
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{
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typeof(sbyte),
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typeof(byte),
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typeof(short),
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typeof(ushort),
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typeof(int),
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typeof(uint),
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typeof(long),
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typeof(ulong),
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typeof(float),
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typeof(double),
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typeof(decimal)
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});
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public SumFilterParser(IResourceFactory resourceFactory)
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: base(resourceFactory)
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{
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}
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protected override bool IsFunction(string name)
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{
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if (name == SumExpression.Keyword)
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{
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return true;
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}
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return base.IsFunction(name);
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}
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protected override FunctionExpression ParseFunction()
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{
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if (TokenStack.TryPeek(out Token? nextToken) && nextToken is { Kind: TokenKind.Text, Value: SumExpression.Keyword })
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{
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return ParseSum();
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}
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return base.ParseFunction();
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}
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private SumExpression ParseSum()
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{
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EatText(SumExpression.Keyword);
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EatSingleCharacterToken(TokenKind.OpenParen);
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ResourceFieldChainExpression targetToManyRelationshipChain = ParseFieldChain(SingleToManyRelationshipChain, FieldChainPatternMatchOptions.None,
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ResourceTypeInScope, "To-many relationship expected.");
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EatSingleCharacterToken(TokenKind.Comma);
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QueryExpression selector = ParseSumSelectorInScope(targetToManyRelationshipChain);
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EatSingleCharacterToken(TokenKind.CloseParen);
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return new SumExpression(targetToManyRelationshipChain, selector);
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}
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private QueryExpression ParseSumSelectorInScope(ResourceFieldChainExpression targetChain)
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{
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var toManyRelationship = (HasManyAttribute)targetChain.Fields.Single();
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using IDisposable scope = InScopeOfResourceType(toManyRelationship.RightType);
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return ParseSumSelector();
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}
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private QueryExpression ParseSumSelector()
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{
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int position = GetNextTokenPositionOrEnd();
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if (TokenStack.TryPeek(out Token? nextToken) && nextToken is { Kind: TokenKind.Text } && IsFunction(nextToken.Value!))
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{
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FunctionExpression function = ParseFunction();
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if (!IsNumericType(function.ReturnType))
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{
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throw new QueryParseException("Function that returns a numeric type expected.", position);
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}
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return function;
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}
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ResourceFieldChainExpression fieldChain = ParseFieldChain(BuiltInPatterns.ToOneChainEndingInAttribute, FieldChainPatternMatchOptions.None,
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ResourceTypeInScope, null);
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var attrAttribute = (AttrAttribute)fieldChain.Fields[^1];
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if (!IsNumericType(attrAttribute.Property.PropertyType))
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{
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throw new QueryParseException("Attribute of a numeric type expected.", position);
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}
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return fieldChain;
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}
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private static bool IsNumericType(Type type)
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{
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Type innerType = Nullable.GetUnderlyingType(type) ?? type;
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return NumericTypes.Contains(innerType);
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}
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}

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