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QueryParameter Class

Contains methods and properties that allow you to conditionally filter data loaded from a MongoDB instance.

Namespace: DevExpress.DataAccess.MongoDB

Assembly: DevExpress.DataAccess.v21.1.dll

Declaration

public sealed class QueryParameter :
    DataSourceParameterBase

Example

The example below demonstrates how to use the MongoDBDataSource class to bind an application or component to a MongoDB instance. The example uses the MongoDBCustomConnectionParameters class to specify a connection string to the MongoDB instance and the MongoDBQuery class to specify data queries to the Categories and Products collections of the Northwind database.

using DevExpress.DataAccess.ConnectionParameters;
using DevExpress.DataAccess.MongoDB;
// ...
// Create a MongoDBCustomConnectionParameters object and assign
// a MongoDB connection string to the object's ConnectionString
// property.
var connectionParameters = new MongoDBCustomConnectionParameters() {
    ConnectionString = "mongodb://localhost:27017"
};

// Specify queries to database collections.
var queryParamLowPrice = new QueryParameter() {
    Name = "LowPrice",
    Type = typeof(int),
    Value = 10
};

var queryLowPriceProducts = new MongoDBQuery() {
    DatabaseName = "Northwind",
    CollectionName = "Products",
    Alias = "LowPriceProducts",
    FilterString = "[UnitPrice] <= ?LowPrice",
    Parameters = { queryParamLowPrice }
};

var queryParamHighPrice = new QueryParameter() {
    Name = "HighPrice",
    Type = typeof(int),
    Value = 40
};

var queryHighPriceProducts = new MongoDBQuery() {
    DatabaseName = "Northwind",
    CollectionName = "Products",
    Alias = "HighPriceProducts",
    FilterString = "[UnitPrice] >= ?HighPrice",
    Parameters = { queryParamHighPrice }
};

// Create a MongoDBDataSource object. Assign the created connection
// string to the object's ConnectionParameters property. Add the
// queries to the object's Queries collection.
var mongoDBDataSource = new MongoDBDataSource() {
    ConnectionParameters = connectionParameters,
    Queries = { queryLowPriceProducts, queryHighPriceProducts }
};

// Call the Fill method of the MongoDBDataSource object to execute the
// queries and load data from the MongoDB instance.
mongoDBDataSource.Fill();

// Use the created object as a data source in your application or component.
//...

Inheritance

See Also