private static Expression BuildRelationUpdateBlock(
EntityFieldInfo fromKey, PropertyInfo fromProperty, EntityInfo toEntity, PropertyInfo toProperty, Expression varFromEntity, Expression varDict)
{
var actions = new List <Expression>();
/**
* var posts = dict[blog.BlogId];
* blog.Posts.AddRange(posts);
*/
var toEnumType = typeof(IEnumerable <>).MakeGenericType(toEntity.Type);
var fkExpr = Expression.Property(varFromEntity, fromKey.ClrProperty);
// var posts = dicts[blog.BlogId];
var varTs = Expression.Variable(toEnumType, "rts");
var keyType = varDict.Type.GenericTypeArguments.First();
var castExpr = Expression.Convert(fkExpr, keyType);
var dictItemExpr = Expression.Property(varDict, "Item", castExpr);
var varTsAssignExpr = Expression.Assign(varTs, dictItemExpr);
actions.Add(varTsAssignExpr);
if (fromProperty != null)
{
// blog.Posts.AddRange(posts);
var fmExpr = Expression.Property(varFromEntity, fromProperty);
var constructor = fmExpr.Type.GetConstructor(new[] { varTs.Type });
var cExpr = Expression.New(constructor, varTs);
var arcExpr = Expression.Assign(fmExpr, cExpr);
actions.Add(arcExpr);
}
/**
* foreach (var post in posts)
* post.Blog = blog;
*/
if (toProperty != null)
{
var varToEntity = Expression.Parameter(toEntity.Type, "t");
var tfmExpr = Expression.Property(varToEntity, toProperty);
var tfmAssignExpr = Expression.Assign(tfmExpr, varFromEntity);
var tkLoop = MakeForEach(varTs, varToEntity, tfmAssignExpr);
actions.Add(tkLoop);
}
var updateBlockExpr = Expression.Block(new[] { varTs }, actions.ToArray());
// ContainsKey(TKey key)
var ccExpr = Expression.Call(varDict, "ContainsKey", null, castExpr);
var ifExpr = Expression.IfThen(ccExpr, updateBlockExpr);
return(ifExpr);
}
private static MethodCallExpression GetToDictCall(EntityInfo toEntity, EntityFieldInfo toKey, Expression toParam)
{
// GroupBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
var gParam = Expression.Parameter(toEntity.Type, "t");
var gBody = Expression.Property(gParam, toKey.ClrProperty);
var gLambda = Expression.Lambda(gBody, gParam);
var gCall = Expression.Call(typeof(Enumerable), nameof(Enumerable.GroupBy), new[] { gParam.Type, gBody.Type }, toParam, gLambda);
// ToDictionary<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
var tdParam = Expression.Parameter(typeof(IGrouping <,>).MakeGenericType(toKey.ValType, toEntity.Type));
var tdBody = Expression.Property(tdParam, "Key");
var tdLambda = Expression.Lambda(tdBody, tdParam);
var tdCall = Expression.Call(typeof(Enumerable), nameof(Enumerable.ToDictionary), new[] { tdParam.Type, tdBody.Type }, gCall, tdLambda);
return(tdCall);
}
private static LambdaExpression MakeFillerFunc(
Expression memberExpr, Type fromEnumType, Type toEnumType, EntityInfo fromEntity, EntityInfo toEntity,
EntityFieldInfo fromKey, EntityFieldInfo toKey, PropertyInfo fromProp, PropertyInfo toProp)
{
var fromParam = Expression.Parameter(typeof(List <object>), "fs");
var toParam = Expression.Parameter(typeof(List <object>), "ts");
var varFromArr = Expression.Variable(fromEnumType, "fromArr");
var varToArr = Expression.Variable(toEnumType, "toArr");
var fromCastCall = Expression.Call(typeof(Enumerable), nameof(Enumerable.Cast), new[] { fromEntity.Type }, fromParam);
var toCastCall = Expression.Call(typeof(Enumerable), nameof(Enumerable.Cast), new[] { toEntity.Type }, toParam);
var varFromArrAssign = Expression.Assign(varFromArr, fromCastCall);
var varToArrAssign = Expression.Assign(varToArr, toCastCall);
// create dictionary for toEntities
// var dicts = ps.GroupBy(p => p.BlogId).ToDictionary(bid => bid.Key);
var tdCall = GetToDictCall(toEntity, toKey, varToArr);
var varDict = Expression.Variable(tdCall.Type, "toDict");
var varDictAssignExpr = Expression.Assign(varDict, tdCall);
var varFromEntity = Expression.Parameter(fromEntity.Type, "f");
var ifExpr = BuildRelationUpdateBlock(fromKey, fromProp, toEntity, toProp, varFromEntity, varDict);
var forEachExpr = MakeForEach(varFromArr, varFromEntity, ifExpr);
var codeBlock = Expression.Block(
new[] { varFromArr, varToArr, varDict },
varFromArrAssign, varToArrAssign, varDictAssignExpr, forEachExpr);
return(toEnumType.IsAssignableFrom(memberExpr.Type)
? Expression.Lambda(codeBlock, fromParam, toParam)
: Expression.Lambda(codeBlock, toParam, fromParam));
}