Attaching extra data to a query on the client-side

Problem

Sometimes it's necessary to attach some extra data to each query (based on some user's input on the client-side) and then use that extra data on query execution.

For example, user might want to specify a date (or a period of time) as an additional filter to the any query.

Or it's it might be necessary to set a text filter, so the result set must include only the rows that contain that text.

EasyQuery totally allows to implement such scenarios with minimal efforts.

Solution

Define beforeExecuteQuery handler on the client-side

To add some extra data you can use beforeExecuteQuery event handler which can be defined on view initialization:

var viewOptions = {
    .     .     .     .
	handlers: {
		beforeFetchData = (context, requestData) => {
		    requestData.data = requestData.data || {};
			var filterInput = document.getElementById('dataFilter');
			requestData.data.filter = filterInput.value;
		};
	}
};

var view = new AdvancedSearchView();

.    .    .    .

Now if you check in Developer Tools (on Network tab), each .../execute request now includes ad additional data object in the request payload.

Define custom EasyQueryManager on the server-side

Now to process this additional request data you can create your own implementation of EasyQueryManager and override its ExecuteQueryCore method.

Here is an example:

public class EasyQueryManagerSqlWithFilter : EasyQueryManagerSql
{
    public EasyQueryManagerSqlWithFilter(EasyQueryOptions options, IServiceProvider services) : base(options, services) 
	{
    }

    protected override Task<IEqResultSet> FetchDataCoreAsync(CancellationToken ct)
    {
	    if (ClientData.TryGetValue("filter", out var filter) {
			Query.ExtraConditions.AddSimpleCondition("Orders.OrderDate", "Equals", filter.ToString());
		}

        return base.FetchDataCoreAsync(ct);
    }
}

Here we just reconfigure our current query and add in it an additional condition group with a bunch of conditions like SomeColumns contains 'filter text'

Finally, you need to register your manager class on EasyQuery middleware initialization:

app.UseEasyQuery(options => {
    .    .    .    .
	options.UseManager<EasyQueryManagerSqlWithFilter>();
});

NB: Please note that you can read the ClientData property in any method of your custom manager. For example, here is how you can choose the connection string depending on the parameter defined on the client:

public class EasyQueryManagerSqlWithFilter : EasyQueryManagerSql
{
    .     .     .     .
    protected override DbConnection GetConnectionCore()
    {
        var dbConnection = base.GetConnectionCore();
        if (ClientData.TryGetValue("connection", out var conType)) {
		    if (conType.ToString() == "Type1") {
                dbConnection.ConnectionString = "One connection string";
			}
			else {
                dbConnection.ConnectionString = "Another connection string";
			}
        }
        return dbConnection;
    }
}