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Signum Framework Tutorials Part 2 – Southwind Logic

, 15 Nov 2012
In this part, we will focus on writing business logic, LINQ queries and explain inheritance
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expressionMethodQuery.snippet
expressionProperty.snippet
field.snippet
fieldCreacion.snippet
fieldEuro.snippet
fieldInicioFin.snippet
fieldString.snippet
fiff.snippet
propiedad.snippet
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Template
EntityControlTemplate
MyTemplate.vstemplate
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ui-bg_flat_0_aaaaaa_40x100.png
ui-bg_flat_75_ffffff_40x100.png
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ui-bg_glass_65_ffffff_1x400.png
ui-bg_glass_75_dadada_1x400.png
ui-bg_glass_75_e6e6e6_1x400.png
ui-bg_glass_95_fef1ec_1x400.png
ui-bg_highlight-soft_75_cccccc_1x100.png
ui-icons_222222_256x240.png
ui-icons_2e83ff_256x240.png
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Controllers
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Southwind.Windows
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Southwind.zip
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;
using System.Linq.Expressions;
using System.Data.SqlClient;
using Signum.Utilities;
using System.Diagnostics;
using Signum.Utilities.DataStructures;
using Signum.Entities;
using Signum.Engine;
using Signum.Entities.Reflection;
using Signum.Utilities.Reflection;
using Signum.Utilities.ExpressionTrees;
using System.Collections;
using Signum.Engine.Maps;

namespace Signum.Engine.Linq
{  
    internal static class TranslatorBuilder
    {
        internal static ITranslateResult Build(ProjectionExpression proj)
        {
            Type type = proj.UniqueFunction == null ? proj.Type.ElementType() : proj.Type;

            return miBuildPrivate.GetInvoker(type)(proj);
        }

        static GenericInvoker<Func<ProjectionExpression, ITranslateResult>> miBuildPrivate = new GenericInvoker<Func<ProjectionExpression, ITranslateResult>>(pe => BuildPrivate<int>(pe));

        static TranslateResult<T> BuildPrivate<T>(ProjectionExpression proj)
        {
            var childs = ProjectionGatherer.Gatherer(proj); 
            List<IChildProjection> childProjections = null;
            if (childs.Count > 0)
            {
                childProjections = new List<IChildProjection>();
                foreach (var pChild in childs)
                {
                    IChildProjection item = BuildChild(pChild.Projection);
                    childProjections.Add(item);
                }
            }

            Scope scope = new Scope
            {
                Alias = proj.Source.Alias,
                Positions = proj.Source.Columns.Select((c, i) => new { c.Name, i }).ToDictionary(p => p.Name, p => p.i),
            };

            Expression<Func<IProjectionRow, T>> lambda = ProjectionBuilder.Build<T>(proj.Projector, scope);

            Expression<Func<SqlParameter[]>> createParams;
            string sql = QueryFormatter.Format(proj.Source, out createParams);

            var result = new TranslateResult<T>
            {
                ChildProjections = childProjections,   

                CommandText = sql,

                ProjectorExpression = lambda,

                GetParameters = createParams.Compile(),
                GetParametersExpression = createParams,

                Unique = proj.UniqueFunction,
            };

            return result;
        }

        static IChildProjection BuildChild(ProjectionExpression proj)
        {
            Type type = proj.UniqueFunction == null ? proj.Type.ElementType() : proj.Type;

            if(!type.IsInstantiationOf(typeof(KeyValuePair<,>)))
                throw new InvalidOperationException("All child projections should create KeyValuePairs");

            return miBuildChildPrivate.GetInvoker(type.GetGenericArguments())(proj);
        }

        static GenericInvoker<Func<ProjectionExpression, IChildProjection>> miBuildChildPrivate = new GenericInvoker<Func<ProjectionExpression, IChildProjection>>(proj => BuildChildPrivate<int, bool>(proj));

        static ChildProjection<K, V> BuildChildPrivate<K, V>(ProjectionExpression proj)
        {
            Scope scope = new Scope
            {
                Alias = proj.Source.Alias,
                Positions = proj.Source.Columns.Select((c, i) => new { c.Name, i }).ToDictionary(p => p.Name, p => p.i),
            };

            Expression<Func<IProjectionRow, KeyValuePair<K, V>>> lambda = ProjectionBuilder.Build<KeyValuePair<K, V>>(proj.Projector, scope);

            Expression<Func<SqlParameter[]>> createParams;
            string sql = QueryFormatter.Format(proj.Source, out createParams);

            var result = new ChildProjection<K, V>
            {
                Name = proj.Token,

                CommandText = sql,
                ProjectorExpression = lambda,

                GetParameters = createParams.Compile(),
                GetParametersExpression = createParams,
            };

            return result;
        }

        public static CommandResult BuildCommandResult(CommandExpression command)
        {
            Expression<Func<SqlParameter[]>> createParams;
            string sql = QueryFormatter.Format(command, out createParams);

            return new CommandResult
            {
                GetParameters = createParams.Compile(),
                GetParametersExpression = createParams,
                CommandText = sql,
            }; 
        }

        public class ProjectionGatherer : DbExpressionVisitor
        {
            List<ChildProjectionExpression> list = new List<ChildProjectionExpression>();

            public static List<ChildProjectionExpression> Gatherer(ProjectionExpression proj)
            {
                ProjectionGatherer pg = new ProjectionGatherer();

                pg.Visit(proj);


                return pg.list; 
            }

            protected override Expression VisitChildProjection(ChildProjectionExpression child)
            {
                var result =  base.VisitChildProjection(child);

                list.Add(child);

                return result;
            }
        }

        /// <summary>
        /// ProjectionBuilder is a visitor that converts an projector expression
        /// that constructs result objects out of ColumnExpressions into an actual
        /// LambdaExpression that constructs result objects out of accessing fields
        /// of a ProjectionRow
        /// </summary>
        public class ProjectionBuilder : DbExpressionVisitor
        {
            static ParameterExpression row = Expression.Parameter(typeof(IProjectionRow), "row");

            static PropertyInfo piRetriever = ReflectionTools.GetPropertyInfo((IProjectionRow r) => r.Retriever);
            static MemberExpression retriever = Expression.Property(row, piRetriever); 
           
            public PropertyInfo piToStrLite = ReflectionTools.GetPropertyInfo((Lite l) =>l.ToStr);
            static FieldInfo fiId = ReflectionTools.GetFieldInfo((IdentifiableEntity i) => i.id);

            static MethodInfo miCached = ReflectionTools.GetMethodInfo((IRetriever r) => r.Cached<TypeDN>(null, null)).GetGenericMethodDefinition();
            static MethodInfo miRequest = ReflectionTools.GetMethodInfo((IRetriever r) => r.Request<TypeDN>(null)).GetGenericMethodDefinition();
            static MethodInfo miRequestIBA = ReflectionTools.GetMethodInfo((IRetriever r) => r.RequestIBA<TypeDN>(1, 1)).GetGenericMethodDefinition();
            static MethodInfo miRequestLiteIBA = ReflectionTools.GetMethodInfo((IRetriever r) => r.RequestLiteIBA<TypeDN>(1, 1)).GetGenericMethodDefinition();

            static MethodInfo miGetType = ReflectionTools.GetMethodInfo((Schema s) => s.GetType(1));

            Scope scope; 
        

            static internal Expression<Func<IProjectionRow, T>> Build<T>(Expression expression, Scope scope)
            {
                ProjectionBuilder pb = new ProjectionBuilder() { scope = scope };
                Expression body = pb.Visit(expression);
                return Expression.Lambda<Func<IProjectionRow, T>>(body, row);
            }

            Expression NullifyColumn(Expression exp)
            {
                ColumnExpression ce = exp as ColumnExpression;
                if (ce == null)
                    return exp;

                if (ce.Type.IsNullable() || ce.Type.IsClass)
                    return ce;

                return new ColumnExpression(ce.Type.Nullify(), ce.Alias, ce.Name);
            }

            protected override Expression VisitUnary(UnaryExpression u)
            {
                if (u.NodeType == ExpressionType.Convert && u.Operand is ColumnExpression && DiffersInNullability(u.Type, u.Operand.Type))
                {
                    ColumnExpression column = (ColumnExpression)u.Operand;
                    return scope.GetColumnExpression(row, column.Alias, column.Name, u.Type);
                }

                return base.VisitUnary(u);
            }

            bool DiffersInNullability(Type a, Type b)
            {
                return
                    a.IsValueType && a.Nullify() == b ||
                    b.IsValueType && b.Nullify() == a;
            }

            protected override Expression VisitColumn(ColumnExpression column)
            {
                return scope.GetColumnExpression(row, column.Alias, column.Name, column.Type);
            }

            protected override Expression VisitChildProjection(ChildProjectionExpression child)
            {
                Expression outer = Visit(child.OuterKey);

                if (outer != child.OuterKey)
                    child = new ChildProjectionExpression(child.Projection, outer); 

                return scope.Lookup(row, child);
            }

            protected override Expression VisitProjection(ProjectionExpression proj)
            {
                throw new InvalidOperationException("No ProjectionExpressions expected at this stage"); 
            }

            protected override Expression VisitFieldInit(FieldInitExpression fieldInit)
            {
                Expression id = Visit(NullifyColumn(fieldInit.ExternalId));

                if (fieldInit.TableAlias == null)
                    return Expression.Call(retriever, miRequest.MakeGenericMethod(fieldInit.Type), id);

                ParameterExpression e = Expression.Parameter(fieldInit.Type, fieldInit.Type.Name.ToLower().Substring(0, 1));

                var block = Expression.Block(
                    fieldInit.Bindings
                    .Where(a => !ReflectionTools.FieldEquals(FieldInitExpression.IdField, a.FieldInfo))
                    .Select(b => Expression.Assign(
                        Expression.Field(e, b.FieldInfo),
                        ExpressionTools.Convert(Visit(b.Binding), b.FieldInfo.FieldType)
                    )));

                LambdaExpression lambda = Expression.Lambda(typeof(Action<>).MakeGenericType(fieldInit.Type), block, e);

                return Expression.Call(retriever, miCached.MakeGenericMethod(fieldInit.Type), id, lambda);
            }

            static PropertyInfo piModified = ReflectionTools.GetPropertyInfo((ModifiableEntity me) => me.Modified);

            static MemberBinding resetModified = Expression.Bind(piModified, Expression.Constant(null, typeof(bool?)));

            protected override Expression VisitEmbeddedFieldInit(EmbeddedFieldInitExpression efie)
            {
                Expression ctor = Expression.MemberInit(Expression.New(efie.Type),
                       efie.Bindings.Select(b => Expression.Bind(b.FieldInfo, Visit(b.Binding))).And(resetModified));
                
                if (efie.HasValue == null)
                    return ctor;

                return Expression.Condition(Expression.Equal(Visit(efie.HasValue.Nullify()), Expression.Constant(true, typeof(bool?))), ctor, Expression.Constant(null, ctor.Type));
            }

            protected override Expression VisitImplementedBy(ImplementedByExpression rb)
            {
                return rb.Implementations.Select(fie => new When(Visit(fie.Field.ExternalId).NotEqualsNulll(), Visit(fie.Field))).ToCondition(rb.Type);
            }

            protected override Expression VisitImplementedByAll(ImplementedByAllExpression rba)
            {
                return Expression.Call(retriever, miRequestIBA.MakeGenericMethod(rba.Type),
                    Visit(NullifyColumn(rba.Id)),
                    Visit(NullifyColumn(rba.TypeId)));
            }

            protected override Expression VisitLiteReference(LiteReferenceExpression lite)
            {
                var id = Visit(NullifyColumn(lite.Id));
                var toStr = Visit(lite.ToStr);
                var typeId = Visit(NullifyColumn(lite.TypeId));

                Type liteType = Reflector.ExtractLite(lite.Type);

                if (id == null)
                    return Expression.Constant(null, lite.Type);
                else if (toStr == null)
                {
                    return Expression.Call(retriever, miRequestLiteIBA.MakeGenericMethod(liteType), id.Nullify(), typeId.Nullify());
                }
                else
                {
                    int? constantTypeId = ConstantValue(typeId);

                    Expression type = constantTypeId.HasValue ? 
                            (Expression) Expression.Constant(Schema.Current.GetType(constantTypeId.Value)):
                            (Expression) Expression.Call(Expression.Constant(Schema.Current), miGetType, typeId.UnNullify());

                    NewExpression liteConstructor;
                    if (type.NodeType == ExpressionType.Constant && (Type)(((ConstantExpression)type).Value) == liteType)
                    {
                        ConstructorInfo ciLite = lite.Type.GetConstructor(new[] { typeof(int), typeof(string) });
                        liteConstructor = Expression.New(ciLite, id.UnNullify(), toStr);
                    }
                    else
                    {
                        ConstructorInfo ciLite = lite.Type.GetConstructor(new[] { typeof(Type), typeof(int), typeof(string) });
                        liteConstructor = Expression.New(ciLite, type, id.UnNullify(), toStr);
                    }

                    return Expression.Condition(id.NotEqualsNulll(), liteConstructor, Expression.Constant(null, lite.Type));
                }
            }

            protected override Expression VisitMListElement(MListElementExpression mle)
            {
                Type type = mle.Type;

                return Expression.MemberInit(Expression.New(type),
                    Expression.Bind(type.GetProperty("RowId"), Visit(mle.RowId)),
                    Expression.Bind(type.GetProperty("Parent"), Visit(mle.Parent)),
                    Expression.Bind(type.GetProperty("Element"), Visit(mle.Element)));
            }

            private int? ConstantValue(Expression typeId)
            {
                if (typeId.NodeType == ExpressionType.Convert)
                    typeId = ((UnaryExpression)typeId).Operand;

                if (typeId.NodeType == ExpressionType.Constant)
                    return (int)((ConstantExpression)typeId).Value;

                return null;
            }

            static ConstructorInfo ciLite = ReflectionTools.GetConstuctorInfo(() => new Lite<IdentifiableEntity>(typeof(IdentifiableEntity), 2, ""));

            protected override Expression VisitSqlConstant(SqlConstantExpression sce)
            {
                return Expression.Constant(sce.Value, sce.Type);
            }

            //protected override Expression VisitSqlFunction(SqlFunctionExpression sqlFunction)
            //{
            //    if (sqlFunction.SqlFunction == SqlFunction.COALESCE.ToString())
            //    {
            //        var result = sqlFunction.Arguments.Select(a => Visit(a.Nullify())).Aggregate((a, b) => Expression.Coalesce(a, b));

            //        if (!sqlFunction.Type.IsNullable())
            //            return result.UnNullify();
            //        return result; 
            //    }

            //    return base.VisitSqlFunction(sqlFunction);
            //}
        }
    }

    internal class Scope
    {
        public Alias Alias;

        public Dictionary<string, int> Positions;

        static PropertyInfo miReader = ReflectionTools.GetPropertyInfo((IProjectionRow row) => row.Reader);

        public Expression GetColumnExpression(Expression row, Alias alias, string name, Type type)
        {
            if (alias != Alias)
                throw new InvalidOperationException("alias '{0}' not found".Formato(alias));

            int position = Positions.GetOrThrow(name, "column name '{0}' not found in alias '" + alias + "'");

            return FieldReader.GetExpression(Expression.Property(row, miReader), position, type);
        }

        static MethodInfo miLookup = ReflectionTools.GetMethodInfo((IProjectionRow row) => row.Lookup<int, double>(null, 0)).GetGenericMethodDefinition();
        
        public Expression Lookup(Expression row, ChildProjectionExpression cProj)
        {
            Type t = cProj.Projection.UniqueFunction == null ? cProj.Type.ElementType() : cProj.Type;

            MethodInfo mi = miLookup.MakeGenericMethod(cProj.OuterKey.Type, t);

            Expression call = Expression.Call(row, mi, Expression.Constant(cProj.Projection.Token), cProj.OuterKey);

            if (cProj.Projection.UniqueFunction == null)
            {
                return call;
            }

            MethodInfo miUnique = UniqueMethod(cProj.Projection.UniqueFunction.Value); 
            return Expression.Call(miUnique.MakeGenericMethod(t), call);
        }


        static MethodInfo miSingle = ReflectionTools.GetMethodInfo(() => Enumerable.Single<int>(null)).GetGenericMethodDefinition();
        static MethodInfo miSingleOrDefault = ReflectionTools.GetMethodInfo(() => Enumerable.SingleOrDefault<int>(null)).GetGenericMethodDefinition();
        static MethodInfo miFirst = ReflectionTools.GetMethodInfo(() => Enumerable.First<int>(null)).GetGenericMethodDefinition();
        static MethodInfo miFirstOrDefault = ReflectionTools.GetMethodInfo(() => Enumerable.FirstOrDefault<int>(null)).GetGenericMethodDefinition();

        internal MethodInfo UniqueMethod(UniqueFunction uniqueFunction)
        {
            switch (uniqueFunction)
            {
                case UniqueFunction.First: return miFirst;
                case UniqueFunction.FirstOrDefault: return miFirstOrDefault;
                case UniqueFunction.Single: return miSingle;
                case UniqueFunction.SingleOrDefault: return miSingleOrDefault;
                default:
                    throw new InvalidOperationException();
            }
        }
    }
}

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About the Author

Olmo del Corral
Software Developer (Senior) Signum Software
Spain Spain
I'm Computer Scientist, one of the founders of Signum Software, and the lead developer behind Signum Framework.
 
www.signumframework.com
 
I love programming in C#, Linq, Compilers, Algorithms, Functional Programming, Computer Graphics, Maths...

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