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Sql.ExpressionAttribute.cs
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Sql.ExpressionAttribute.cs
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using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using System.Text.RegularExpressions;
using JetBrains.Annotations;
namespace LinqToDB
{
using Common.Internal;
using Expressions;
using Extensions;
using Linq.Builder;
using Mapping;
using SqlQuery;
partial class Sql
{
/// <summary>
/// An Attribute that allows custom Expressions to be defined
/// for a Method used within a Linq Expression.
/// </summary>
[PublicAPI]
[Serializable]
[AttributeUsage(AttributeTargets.Property | AttributeTargets.Method, AllowMultiple = true, Inherited = false)]
public class ExpressionAttribute : MappingAttribute
{
/// <summary>
/// Creates an Expression that will be used in SQL,
/// in place of the method call decorated by this attribute.
/// </summary>
/// <param name="expression">The SQL expression. Use {0},{1}... for parameters given to the method call.</param>
public ExpressionAttribute(string? expression)
{
Expression = expression;
Precedence = SqlQuery.Precedence.Primary;
IsPure = true;
}
/// <summary>
/// Creates an Expression that will be used in SQL,
/// in place of the method call decorated by this attribute.
/// </summary>
/// <param name="expression">The SQL expression. Use {0},{1}... for parameters given to the method call.</param>
/// <param name="argIndices">Used for setting the order of the method arguments
/// being passed into the function.</param>
public ExpressionAttribute(string expression, params int[] argIndices)
{
Expression = expression;
ArgIndices = argIndices;
Precedence = SqlQuery.Precedence.Primary;
IsPure = true;
}
/// <summary>
/// Creates an Expression that will be used in SQL,
/// for the <see cref="ProviderName"/> specified,
/// in place of the method call decorated by this attribute.
/// </summary>
/// <param name="expression">The SQL expression. Use {0},{1}... for parameters given to the method call.</param>
/// <param name="configuration">The Database configuration for which this Expression will be used.</param>
public ExpressionAttribute(string configuration, string expression)
{
Configuration = configuration;
Expression = expression;
Precedence = SqlQuery.Precedence.Primary;
IsPure = true;
}
/// <summary>
/// Creates an Expression that will be used in SQL,
/// for the <see cref="ProviderName"/> specified,
/// in place of the method call decorated by this attribute.
/// </summary>
/// <param name="expression">The SQL expression. Use {0},{1}... for parameters given to the method call.</param>
/// <param name="configuration">The Database configuration for which this Expression will be used.</param>
/// <param name="argIndices">Used for setting the order of the method arguments
/// being passed into the function.</param>
public ExpressionAttribute(string configuration, string expression, params int[] argIndices)
{
Configuration = configuration;
Expression = expression;
ArgIndices = argIndices;
Precedence = SqlQuery.Precedence.Primary;
IsPure = true;
}
/// <summary>
/// The expression to be used in building the SQL.
/// </summary>
public string? Expression { get; set; }
/// <summary>
/// The order of Arguments to be passed
/// into the function from the method call.
/// </summary>
public int[]? ArgIndices { get; set; }
/// <summary>
/// Determines the priority of the expression in evaluation.
/// Refer to <see cref="SqlQuery.Precedence"/>.
/// </summary>
public int Precedence { get; set; }
/// <summary>
/// If <c>true</c> The expression will only be evaluated on the
/// database server. If it cannot, an exception will
/// be thrown.
/// </summary>
public bool ServerSideOnly { get; set; }
/// <summary>
/// If <c>true</c> a greater effort will be made to execute
/// the expression on the DB server instead of in .NET.
/// </summary>
public bool PreferServerSide { get; set; }
/// <summary>
/// If <c>true</c> inline all parameters passed into the expression.
/// </summary>
public bool InlineParameters { get; set; }
/// <summary>
/// Used internally by <see cref="ExtensionAttribute"/>.
/// </summary>
public bool ExpectExpression { get; set; }
/// <summary>
/// If <c>true</c> the expression is treated as a Predicate
/// And when used in a Where clause will not have
/// an added comparison to 'true' in the database.
/// </summary>
public bool IsPredicate { get; set; }
/// <summary>
/// If <c>true</c>, this expression represents an aggregate result
/// Examples would be SUM(),COUNT().
/// </summary>
public bool IsAggregate { get; set; }
/// <summary>
/// If <c>true</c>, this expression represents a Window Function
/// Examples would be SUM() OVER(), COUNT() OVER().
/// </summary>
public bool IsWindowFunction { get; set; }
/// <summary>
/// If <c>true</c>, it notifies SQL Optimizer that expression returns same result if the same values/parameters are used. It gives optimizer additional information how to simplify query.
/// For example ORDER BY PureFunction("Str") can be removed because PureFunction function uses constant value.
/// <example>
/// For example Random function is NOT Pure function because it returns different result all time.
/// But expression <see cref="CurrentTimestamp"/> is Pure in case of executed query.
/// <see cref="DateAdd(DateParts,double?,System.DateTime?)"/> is also Pure function because it returns the same result with the same parameters.
/// </example>
/// </summary>
public bool IsPure { get; set; }
/// <summary>
/// Used to determine whether the return type should be treated as
/// something that can be null If CanBeNull is not explicitly set.
/// <para>Default is <see cref="IsNullableType.Undefined"/>,
/// which will be treated as <c>true</c></para>
/// </summary>
public IsNullableType IsNullable { get; set; }
/// <summary>
/// if <c>true</c>, do not generate generic parameters.
/// </summary>
public bool IgnoreGenericParameters { get; set; }
internal bool? _canBeNull;
/// <summary>
/// If <c>true</c>, result can be null
/// </summary>
public bool CanBeNull
{
get => _canBeNull ?? true;
set => _canBeNull = value;
}
const string MatchParamPattern = @"{([0-9a-z_A-Z?]*)(,\s'(.*)')?}";
static Regex _matchParamRegEx = new (MatchParamPattern, RegexOptions.Compiled);
public static string ResolveExpressionValues<TContext>(TContext context, string expression, Func<TContext, string, string?, string?> valueProvider, out Expression? error)
{
if (expression == null) throw new ArgumentNullException(nameof(expression));
if (valueProvider == null) throw new ArgumentNullException(nameof(valueProvider));
int prevMatch = -1;
int prevNotEmptyMatch = -1;
bool spaceNeeded = false;
Expression? errorExpr = null;
var str = _matchParamRegEx.Replace(expression, match =>
{
var paramName = match.Groups[1].Value;
var canBeOptional = paramName.EndsWith("?");
if (canBeOptional)
paramName = paramName.TrimEnd('?');
if (paramName == "_")
{
spaceNeeded = true;
prevMatch = match.Index + match.Length;
return string.Empty;
}
var delimiter = match.Groups[3].Success ? match.Groups[3].Value : null;
var calculated = valueProvider(context, paramName, delimiter);
if (string.IsNullOrEmpty(calculated) && !canBeOptional)
{
errorExpr = new SqlErrorExpression($"Non-optional parameter '{paramName}' not found", typeof(string));
return "error";
}
var res = calculated;
if (spaceNeeded)
{
if (!string.IsNullOrEmpty(calculated))
{
var e = expression;
if (prevMatch == match.Index && prevNotEmptyMatch == match.Index - 3 || (prevNotEmptyMatch >= 0 && e[prevNotEmptyMatch] != ' '))
res = " " + calculated;
}
spaceNeeded = false;
}
if (!string.IsNullOrEmpty(calculated))
{
prevNotEmptyMatch = match.Index + match.Length;
}
return res ?? string.Empty;
});
error = errorExpr;
return str;
}
public static readonly SqlExpression UnknownExpression = new ("!!!");
public static void PrepareParameterValues<TContext>(
TContext context,
MappingSchema mappingSchema,
Expression expression,
ref string? expressionStr,
bool includeInstance,
out List<(Expression? expression, ExprParameterAttribute? parameter)> knownExpressions,
bool ignoreGenericParameters,
out List<SqlDataType>? genericTypes,
ConvertFunc<TContext> converter)
{
knownExpressions = new List<(Expression?, ExprParameterAttribute?)>();
genericTypes = null;
if (expression.NodeType == ExpressionType.Call)
{
var mc = (MethodCallExpression) expression;
expressionStr ??= mc.Method.Name;
if (includeInstance && !mc.Method.IsStatic)
knownExpressions.Add((mc.Object, null));
ParameterInfo[]? pis = null;
for (var i = 0; i < mc.Arguments.Count; i++)
{
var arg = mc.Arguments[i];
pis ??= mc.Method.GetParameters();
var p = pis[i];
var paramAttribute = p.GetAttributes<ExprParameterAttribute>().FirstOrDefault();
if (arg is NewArrayExpression nae)
{
if (p.HasAttribute<ParamArrayAttribute>())
{
foreach (var e in nae.Expressions)
{
knownExpressions.Add((e, paramAttribute));
}
}
else
{
knownExpressions.Add((nae, paramAttribute));
}
}
else
{
knownExpressions.Add((arg, paramAttribute));
}
}
if (!ignoreGenericParameters)
{
ParameterInfo[]? pi = null;
if (mc.Method.DeclaringType!.IsGenericType)
{
genericTypes = new List<SqlDataType>();
foreach (var t in mc.Method.DeclaringType.GetGenericArguments())
{
var type = mappingSchema.GetDataType(t);
if (type.Type.DataType == DataType.Undefined)
{
pi ??= mc.Method.GetParameters();
for (var i = 0; i < pi.Length; i++)
{
if (pi[i].ParameterType == t)
{
var paramAttribute = pi[i].GetAttributes<ExprParameterAttribute>().FirstOrDefault();
var converted = converter(context, mc.Arguments[i], null, paramAttribute?.DoNotParameterize);
if (converted is SqlPlaceholderExpression placeholder)
{
var dbType = QueryHelper.GetDbDataType(placeholder.Sql, mappingSchema);
if (dbType.DataType != DataType.Undefined)
type = new SqlDataType(dbType);
}
}
}
}
genericTypes.Add(type);
}
}
if (mc.Method.IsGenericMethod)
{
genericTypes ??= new List<SqlDataType>();
foreach (var t in mc.Method.GetGenericArguments())
{
var type = mappingSchema.GetDataType(t);
if (type.Type.DataType == DataType.Undefined)
{
pi ??= mc.Method.GetParameters();
for (var i = 0; i < pi.Length; i++)
{
if (pi[i].ParameterType == t)
{
var paramAttribute = pi[i].GetAttributes<ExprParameterAttribute>().FirstOrDefault();
var converted = converter(context, mc.Arguments[i], null, paramAttribute?.DoNotParameterize);
if (converted is SqlPlaceholderExpression placeholder)
{
var dbType = QueryHelper.GetDbDataType(placeholder.Sql, mappingSchema);
if (dbType.DataType != DataType.Undefined)
type = new SqlDataType(dbType);
}
}
}
}
genericTypes.Add(type);
}
}
}
}
else
{
var me = (MemberExpression) expression;
expressionStr ??= me.Member.Name;
if (me.Expression != null)
knownExpressions.Add((me.Expression, null));
}
}
public delegate Expression ConvertFunc<TContext>(TContext context, Expression expression, ColumnDescriptor? columnDescriptor, bool? inlineParameters);
public static ISqlExpression?[] PrepareArguments<TContext>(TContext context,
string expressionStr,
int[]? argIndices,
bool addDefault,
List<(Expression? expression, ExprParameterAttribute? parameter)> knownExpressions,
List<SqlDataType>? genericTypes,
ConvertFunc<TContext> converter,
out Expression? error)
{
var parms = new List<ISqlExpression?>();
var ctx = WritableContext.Create((found: false, error: (Expression?)null), (context, expressionStr, argIndices, knownExpressions, genericTypes, converter, parms));
ResolveExpressionValues(
ctx,
expressionStr!,
static (ctx, v, d) =>
{
ctx.WriteableValue = (true, ctx.WriteableValue.error);
var argIdx = int.Parse(v, NumberFormatInfo.InvariantInfo);
var idx = argIdx;
if (ctx.StaticValue.argIndices != null)
{
if (idx < 0 || idx >= ctx.StaticValue.argIndices.Length)
throw new LinqToDBException(FormattableString.Invariant($"Expression '{ctx.StaticValue.expressionStr}' has wrong ArgIndices mapping. Index '{idx}' do not fit in range."));
idx = ctx.StaticValue.argIndices[idx];
}
if (idx < 0)
throw new LinqToDBException(FormattableString.Invariant($"Expression '{ctx.StaticValue.expressionStr}' has wrong param index mapping. Index '{idx}' do not fit in range."));
while (idx >= ctx.StaticValue.parms.Count)
{
ctx.StaticValue.parms.Add(null);
}
if (ctx.StaticValue.parms[idx] == null)
{
ISqlExpression? paramExpr = null;
if (argIdx >= ctx.StaticValue.knownExpressions.Count)
{
var typeIndex = argIdx - ctx.StaticValue.knownExpressions.Count;
if (ctx.StaticValue.genericTypes == null || typeIndex >= ctx.StaticValue.genericTypes.Count || typeIndex < 0)
{
throw new LinqToDBException(FormattableString.Invariant($"Expression '{ctx.StaticValue.expressionStr}' has wrong param index mapping. Index '{argIdx}' do not fit in parameters range."));
}
paramExpr = ctx.StaticValue.genericTypes[typeIndex];
}
else
{
var (expression, parameter) = ctx.StaticValue.knownExpressions[argIdx];
if (expression != null)
{
var converted = ctx.StaticValue.converter(ctx.StaticValue.context, expression, null, parameter?.DoNotParameterize);
if (converted is SqlPlaceholderExpression placeholder)
{
paramExpr = placeholder.Sql;
}
else
{
paramExpr = null;
ctx.WriteableValue = (true, converted);
}
}
}
ctx.StaticValue.parms[idx] = paramExpr;
}
return v;
}, out error);
if (error != null)
return [];
if (!ctx.WriteableValue.found)
{
// It means that we have to prepare parameters for function
if (argIndices != null)
{
for (var idx = 0; idx < argIndices.Length; idx++)
{
var argIdx = argIndices[idx];
while (idx >= parms.Count)
{
parms.Add(null);
}
if (parms[idx] == null)
{
ISqlExpression? paramExpr = null;
if (argIdx >= knownExpressions.Count)
{
var typeIndex = argIdx - knownExpressions.Count;
if (genericTypes == null || typeIndex >= genericTypes.Count || typeIndex < 0)
{
throw new LinqToDBException(FormattableString.Invariant($"Function '{expressionStr}' has wrong param index mapping. Index '{argIdx}' do not fit in parameters range."));
}
paramExpr = genericTypes[typeIndex];
}
else
{
var (expression, parameter) = knownExpressions[argIdx];
if (expression != null)
{
var converted = converter(context, expression, null, parameter?.DoNotParameterize);
if (converted is SqlPlaceholderExpression placeholder)
{
paramExpr = placeholder.Sql;
}
else
{
// do not allow overriding first error
if (ctx.WriteableValue.error == null)
ctx.WriteableValue = (true, error);
paramExpr = null;
}
}
}
parms[idx] = paramExpr;
}
}
}
else
{
if (addDefault)
{
foreach (var (expression, parameter) in knownExpressions)
{
if (expression == null)
parms.Add(null);
else
{
var converted = converter(context, expression, null, parameter?.DoNotParameterize);
if (converted is SqlPlaceholderExpression placeholder)
parms.Add(placeholder.Sql);
else
{
error = expression;
}
}
}
if (genericTypes != null)
parms.AddRange(genericTypes);
}
}
}
if (ctx.WriteableValue.error != null)
{
error = ctx.WriteableValue.error;
return parms.Select(static p => p).ToArray();
}
return parms.Select(static p => p ?? UnknownExpression).ToArray();
}
public virtual Expression GetExpression<TContext>(
TContext context,
IDataContext dataContext,
IExpressionEvaluator evaluator,
SelectQuery query,
Expression expression,
ConvertFunc<TContext> converter)
{
var expressionStr = Expression;
PrepareParameterValues(context, dataContext.MappingSchema, expression, ref expressionStr, true, out var knownExpressions, IgnoreGenericParameters, out var genericTypes, converter);
if (string.IsNullOrEmpty(expressionStr))
throw new LinqToDBException($"Cannot retrieve SQL Expression body from expression '{expression}'.");
var parameters = PrepareArguments(context, expressionStr!, ArgIndices, false, knownExpressions, genericTypes, converter, out var error);
if (error != null)
return SqlErrorExpression.EnsureError(error, expression.Type);
var sqlExpression = new SqlExpression(expression.Type, expressionStr!, Precedence,
(IsAggregate ? SqlFlags.IsAggregate : SqlFlags.None) |
(IsPure ? SqlFlags.IsPure : SqlFlags.None) |
(IsPredicate ? SqlFlags.IsPredicate : SqlFlags.None) |
(IsWindowFunction ? SqlFlags.IsWindowFunction : SqlFlags.None),
ToParametersNullabilityType(IsNullable),
_canBeNull,
parameters!);
if (_canBeNull != null)
sqlExpression.CanBeNull = _canBeNull.Value;
// placeholder will be updated later by concrete path
return ExpressionBuilder.CreatePlaceholder(query, sqlExpression, expression);
}
public static ParametersNullabilityType ToParametersNullabilityType(IsNullableType nullableType)
{
return (ParametersNullabilityType)nullableType;
}
public virtual bool GetIsPredicate(Expression expression) => IsPredicate;
public override string GetObjectID()
{
return FormattableString.Invariant($".{Configuration}.{Expression}.{IdentifierBuilder.GetObjectID(ArgIndices)}.{Precedence}.{(ServerSideOnly ? 1 : 0)}.{(PreferServerSide ? 1 : 0)}.{(InlineParameters ? 1 : 0)}.{(ExpectExpression ? 1 : 0)}.{(IsPredicate ? 1 : 0)}.{(IsAggregate ? 1 : 0)}.{(IsWindowFunction ? 1 : 0)}.{(IsPure ? 1 : 0)}.{(int)IsNullable}.{(IgnoreGenericParameters ? 1 : 0)}.{(CanBeNull ? 1 : 0)}.");
}
}
}
}