/// <summary>
/// Initializes a new instance of the <see cref="ApiDataReference" /> class.
/// </summary>
/// <param name="context">
/// A query context.
/// </param>
/// <param name="name">
/// The name of an entity set, singleton or function import.
/// </param>
public ApiDataReference(QueryContext context, string name)
{
Ensure.NotNull(context, "context");
Ensure.NotNull(name, "name");
this.context = context;
this.name = name;
}
/// <summary>
/// Initializes a new instance of the <see cref="DataSourceStubModelReference" /> class.
/// </summary>
/// <param name="context">
/// A query context.
/// </param>
/// <param name="name">
/// The name of an entity set, singleton or function import.
/// </param>
internal DataSourceStubModelReference(QueryContext context, string name)
{
Ensure.NotNull(context, "context");
Ensure.NotNull(name, "name");
this.context = context;
this.name = name;
}
/// <summary>
/// Initializes a new instance of the <see cref="DataSourceStubReference" /> class referring to a function.
/// </summary>
/// <param name="context">
/// A query context.
/// </param>
/// <param name="namespaceName">
/// The name of a namespace containing the function.
/// </param>
/// <param name="name">
/// The name of a function.
/// </param>
public DataSourceStubReference(
QueryContext context,
string namespaceName,
string name)
{
Ensure.NotNull(context, "context");
Ensure.NotNull(namespaceName, "namespaceName");
Ensure.NotNull(name, "name");
this.context = context;
this.namespaceName = namespaceName;
this.name = name;
}
/// <summary>
/// Initializes a new instance of the <see cref="QueryExpressionContext" /> class.
/// </summary>
/// <param name="queryContext">
/// A query context.
/// </param>
public QueryExpressionContext(QueryContext queryContext)
{
Ensure.NotNull(queryContext, "queryContext");
this.QueryContext = queryContext;
}
/// <summary>
/// Asynchronously executes the query flow.
/// </summary>
/// <param name="context">
/// The query context.
/// </param>
/// <param name="cancellationToken">
/// A cancellation token.
/// </param>
/// <returns>
/// A task that represents the asynchronous
/// operation whose result is a query result.
/// </returns>
public static async Task<QueryResult> QueryAsync(
QueryContext context,
CancellationToken cancellationToken)
{
Ensure.NotNull(context, "context");
// process query expression
var expression = context.Request.Expression;
var visitor = new QueryExpressionVisitor(context);
expression = visitor.Visit(expression);
// get element type
Type elementType = null;
var queryType = expression.Type.FindGenericType(typeof(IQueryable<>));
if (queryType != null)
{
elementType = queryType.GetGenericArguments()[0];
}
// append count expression if requested
if (elementType != null && context.Request.ShouldReturnCount)
{
expression = ExpressionHelpers.Count(expression, elementType);
elementType = null; // now return type is single int
}
// execute query
QueryResult result;
var executor = context.GetHookHandler<IQueryExecutor>();
if (executor == null)
{
throw new NotSupportedException(Resources.QueryExecutorMissing);
}
if (elementType != null)
{
var query = visitor.BaseQuery.Provider.CreateQuery(expression);
var method = typeof(IQueryExecutor)
.GetMethod("ExecuteQueryAsync")
.MakeGenericMethod(elementType);
var parameters = new object[]
{
context, query, cancellationToken
};
var task = method.Invoke(executor, parameters) as Task<QueryResult>;
result = await task;
}
else
{
var method = typeof(IQueryExecutor)
.GetMethod("ExecuteSingleAsync")
.MakeGenericMethod(expression.Type);
var parameters = new object[]
{
context, visitor.BaseQuery, expression, cancellationToken
};
var task = method.Invoke(executor, parameters) as Task<QueryResult>;
result = await task;
}
if (result != null)
{
result.ResultsSource = visitor.EntitySet;
}
return result;
}
public QueryExpressionVisitor(QueryContext context)
{
this.context = new QueryExpressionContext(context);
this.processedExpressions = new Dictionary<Expression, Expression>();
}
private static async Task ExecuteSubExpression(
QueryContext context,
CancellationToken cancellationToken,
QueryExpressionVisitor visitor,
IQueryExecutor executor,
Expression expression)
{
// get element type
Type elementType = null;
var queryType = expression.Type.FindGenericType(typeof(IQueryable<>));
if (queryType != null)
{
elementType = queryType.GetGenericArguments()[0];
}
var query = visitor.BaseQuery.Provider.CreateQuery(expression);
var method = typeof(IQueryExecutor)
.GetMethod("ExecuteQueryAsync")
.MakeGenericMethod(elementType);
var parameters = new object[]
{
context, query, cancellationToken
};
var task = method.Invoke(executor, parameters) as Task<QueryResult>;
var result = await task;
var any = result.Results.Cast<object>().Any();
if (!any)
{
// Which means previous expression does not have result, and should throw ResourceNotFoundException.
throw new ResourceNotFoundException(Resources.ResourceNotFound);
}
}
private static async Task CheckSubExpressionResult(
QueryContext context,
CancellationToken cancellationToken,
IEnumerable enumerableResult,
QueryExpressionVisitor visitor,
IQueryExecutor executor,
Expression expression)
{
if (enumerableResult.GetEnumerator().MoveNext())
{
// If there is some result, will not have additional processing
return;
}
var methodCallExpression = expression as MethodCallExpression;
// This will remove unneeded statement which includes $expand, $select,$top,$skip,$orderby
methodCallExpression = methodCallExpression.RemoveUnneededStatement();
if (methodCallExpression == null || methodCallExpression.Arguments.Count != 2)
{
return;
}
if (methodCallExpression.Method.Name == ExpressionMethodNameOfWhere)
{
// Throw exception if key as last where statement, or remove $filter where statement
methodCallExpression = CheckWhereCondition(methodCallExpression);
if (methodCallExpression == null || methodCallExpression.Arguments.Count != 2)
{
return;
}
// Call without $filter where statement and with Key where statement
if (methodCallExpression.Method.Name == ExpressionMethodNameOfWhere)
{
// The last where from $filter is removed and run with key where statement
await ExecuteSubExpression(context, cancellationToken, visitor, executor, methodCallExpression);
return;
}
}
if (methodCallExpression.Method.Name != ExpressionMethodNameOfSelect
&& methodCallExpression.Method.Name != ExpressionMethodNameOfSelectMany)
{
// If last statement is not select property, will no further checking
return;
}
var subExpression = methodCallExpression.Arguments[0];
// Remove appended statement like Where(Param_0 => (Param_0.Prop != null)) if there is one
subExpression = subExpression.RemoveAppendWhereStatement();
await ExecuteSubExpression(context, cancellationToken, visitor, executor, subExpression);
}
/// <summary>
/// Asynchronously executes the query flow.
/// </summary>
/// <param name="context">
/// The query context.
/// </param>
/// <param name="cancellationToken">
/// A cancellation token.
/// </param>
/// <returns>
/// A task that represents the asynchronous
/// operation whose result is a query result.
/// </returns>
public async Task<QueryResult> QueryAsync(
QueryContext context,
CancellationToken cancellationToken)
{
Ensure.NotNull(context, "context");
// STEP 1: pre-filter
var filters = context.GetHookPoints<IQueryFilter>();
foreach (var filter in filters.Reverse())
{
await filter.FilterRequestAsync(context, cancellationToken);
if (context.Result != null)
{
return context.Result;
}
}
// STEP 2: process query expression
var expression = context.Request.Expression;
var visitor = new QueryExpressionVisitor(context);
expression = visitor.Visit(expression);
// STEP 3: execute query
QueryResult result = null;
var executor = context.GetHookPoint<IQueryExecutor>();
if (executor == null)
{
throw new NotSupportedException();
}
var queryType = expression.Type
.FindGenericType(typeof(IQueryable<>));
if (queryType != null)
{
var query = visitor.BaseQuery.Provider.CreateQuery(expression);
var method = typeof(IQueryExecutor)
.GetMethod("ExecuteQueryAsync")
.MakeGenericMethod(queryType.GetGenericArguments()[0]);
var parameters = new object[]
{
context, query, cancellationToken
};
var task = method.Invoke(executor, parameters) as Task<QueryResult>;
result = await task;
}
else
{
var method = typeof(IQueryExecutor)
.GetMethod("ExecuteSingleAsync")
.MakeGenericMethod(expression.Type);
var parameters = new object[]
{
context, visitor.BaseQuery, expression, cancellationToken
};
var task = method.Invoke(executor, parameters) as Task<QueryResult>;
result = await task;
}
if (result != null)
{
result.ResultsSource = visitor.EntitySet;
}
context.Result = result;
// STEP 4: post-filter
foreach (var filter in filters)
{
await filter.FilterResultAsync(context, cancellationToken);
}
return context.Result;
}
/// <summary>
/// Asynchronously executes the query flow.
/// </summary>
/// <param name="context">
/// The query context.
/// </param>
/// <param name="cancellationToken">
/// A cancellation token.
/// </param>
/// <returns>
/// A task that represents the asynchronous
/// operation whose result is a query result.
/// </returns>
public static async Task <QueryResult> QueryAsync(
QueryContext context,
CancellationToken cancellationToken)
{
Ensure.NotNull(context, nameof(context));
// process query expression
var expression = context.Request.Expression;
var visitor = new QueryExpressionVisitor(context);
expression = visitor.Visit(expression);
// get element type
Type elementType = null;
var queryType = expression.Type.FindGenericType(typeof(IQueryable <>));
if (queryType != null)
{
elementType = queryType.GetGenericArguments()[0];
}
// append count expression if requested
if (elementType != null && context.Request.ShouldReturnCount)
{
expression = ExpressionHelpers.Count(expression, elementType);
elementType = null; // now return type is single int
}
// execute query
QueryResult result;
var executor = context.GetApiService <IQueryExecutor>();
if (executor == null)
{
throw new NotSupportedException(Resources.QueryExecutorMissing);
}
if (elementType != null)
{
var query = visitor.BaseQuery.Provider.CreateQuery(expression);
var method = typeof(IQueryExecutor)
.GetMethod("ExecuteQueryAsync")
.MakeGenericMethod(elementType);
var parameters = new object[]
{
context, query, cancellationToken
};
var task = method.Invoke(executor, parameters) as Task <QueryResult>;
result = await task.ConfigureAwait(false);
await CheckSubExpressionResult(
context, result.Results, visitor, executor, expression, cancellationToken).ConfigureAwait(false);
}
else
{
var method = typeof(IQueryExecutor)
.GetMethod("ExecuteExpressionAsync")
.MakeGenericMethod(expression.Type);
var parameters = new object[]
{
context, visitor.BaseQuery.Provider, expression, cancellationToken
};
var task = method.Invoke(executor, parameters) as Task <QueryResult>;
result = await task.ConfigureAwait(false);
}
if (result != null)
{
result.ResultsSource = visitor.EntitySet;
}
return(result);
}
public QueryExpressionVisitor(QueryContext context)
{
this.context = new QueryExpressionContext(context);
processedExpressions = new Dictionary <Expression, Expression>();
}