How Can I Create a Dynamic WHERE Clause in LINQ to Handle Variable Filtering Criteria?

Dynamic WHERE clause in LINQ

When creating complex LINQ queries, you may need to dynamically assemble WHERE clauses based on user input or other runtime factors. This article explores how to achieve this efficiently using LINQ.

Assemble dynamic WHERE clause

One way to assemble dynamic WHERE clauses is to chain multiple WHERE clauses in a query. This allows you to add or remove filters based on specific criteria.

Here is an example:

<code class="language-csharp">var q = from c in db.ProductDetail
        where c.ProductGroupName == productGroupName && c.ProductTypeName == productTypeName
        select c;

// 动态过滤
foreach (var filter in filterDictionary)
{
    string fieldName = filter.Key;
    List<string> values = filter.Value;

    if (values.Count > 0)
    {
        q = q.Where(c => values.Contains(c[fieldName]));
    }
}</code>

In this example, for each key-value pair in filterDictionary, we check if the corresponding field name has any value. If there are, we add a new WHERE clause to the query that filters the results based on these values.

Link WHERE clause

You can easily create complex and dynamic filter conditions by chaining multiple WHERE clauses. For example, you can filter by multiple fields, check a range of values, or combine multiple conditions using logical operators such as AND or OR. This flexibility allows you to customize queries based on the specific requirements of your scenario.

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