有没有方法来构建一个QueryExpression，让你可以动态地处理数目不详的条件

问题描述

Microsoft提供例如像我抄在下面为一个QueryExpression创建多个条件之一。有没有方法来构建一个QueryExpression，让你可以动态地处理数目不详的条件是什么？在微软下面的例子中，他们使用条件1，条件2等等......再次声明，我不知道是否有创造一个更加可重复使用QueryExpression可以处理可变数目的条件的方法。我知道整件事可以在LINQ中做，但我专门试图确定它是否能够与QueryExpression来完成。

  //创建查询表达式，并设置联系的实体。 
 QueryExpression查询=新QueryExpression（）; 
 query.EntityName =联系; 
 
 //创建其中第一个名称等于乔的条件。 
 ConditionExpression条件1 =新ConditionExpression（）; 
 condition1.AttributeName =名字; 
 condition1.Operator = ConditionOperator.Equal; 
 condition1.Values =新的字符串[] {乔}; 
 
 //创建其中第一个名称等于约翰的另一个条件。 
 ConditionExpression条件2 =新ConditionExpression（）; 
条件2 .AttributeName =名字; 
条件2 .Operator = ConditionOperator.Equal; 
条件2 .Values =新的字符串[] {约翰}; 
  

解决方案

所以，你可以以编程建立QueryExpressions，这可能有助于简化对象的创建。唯一的问题我会提高，就是你可能会发现你的查询是如此的不同，很难建立通用的功能，支持他们。

在这里无论如何都是一个。简单的例子，它应该有希望让你开始

 公共静态QueryExpression BuildQueryExpression（字符串的entityName，columnSet columnSet，logicalOperator logicalOperator，列表与LT; ConditionExpression> ;条件）
 {
 QueryExpression查询=新QueryExpression（的entityName）; 
 query.ColumnSet = columnSet; 
 query.Criteria =新FilterExpression（logicalOperator）; 
 conditions.ForEach（C => query.Criteria.AddCondition（C））; 
返回查询; 
} 
  

用法：

  QueryExpression查询= BuildQueryExpression（接触，新ColumnSet（真），LogicalOperator.And，新的List< ConditionExpression>（）
 {
新ConditionExpression（名字，ConditionOperator.Equal，詹姆斯），
新ConditionExpression（姓氏，ConditionOperator.Equal，木），
}）; 
  

Microsoft provides example like the one I have copied below for creating multiple conditions for a QueryExpression. Is there way to structure a QueryExpression so that you could dynamically handle a unknown number of conditions? In Microsofts example below they use condition1, condition2 and so on... Again I'm wondering if there's a way to create a more reusable QueryExpression that can handle a variable number of conditions. I know the whole thing could be done in LINQ but I'm specifically trying to determine if it could be done with QueryExpression.

// Create the query expression and set the entity to contact.
QueryExpression query = new QueryExpression();
query.EntityName = "contact";

// Create a condition where the first name equals Joe.
ConditionExpression condition1 = new ConditionExpression();
condition1.AttributeName = "firstname";
condition1.Operator = ConditionOperator.Equal;
condition1.Values = new string[] { "Joe" }; 

// Create another condition where the first name equals John.
ConditionExpression condition2 = new ConditionExpression();
condition2 .AttributeName = "firstname";
condition2 .Operator = ConditionOperator.Equal;
condition2 .Values = new string[] { "John" }; 

解决方案

So you could programmatically build QueryExpressions, which might help to streamline object creation. The only issue I would raise, is that you may find your queries are so different it is difficult to create generic functions to support them all.

In any case here is a simple example which should hopefully get you started.

    public static QueryExpression BuildQueryExpression(String entityName, ColumnSet columnSet, LogicalOperator logicalOperator, List<ConditionExpression> conditions)
    {
        QueryExpression query = new QueryExpression(entityName);
        query.ColumnSet = columnSet;
        query.Criteria = new FilterExpression(logicalOperator);
        conditions.ForEach(c => query.Criteria.AddCondition(c));
        return query;
    }

Usage:

    QueryExpression query = BuildQueryExpression("contact", new ColumnSet(true), LogicalOperator.And, new List<ConditionExpression>()
        {
            new ConditionExpression("firstname", ConditionOperator.Equal, "James" ),
            new ConditionExpression("lastname", ConditionOperator.Equal, "Wood" ),
        });

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