public virtual void WriteGroupByExpressionQueryParameter(
GroupByQueryExpression groupByQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
WriteIfNotNull(groupByQueryExpression.Expression, queryExpressionVisitor);
}
public virtual void WriteMultipleStatements(
MultipleStatementQueryExpression multipleStatementQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
WriteExpressionCollection(multipleStatementQueryExpression.Queries, queryExpressionVisitor, seperator: " ");
}
public void Visit(QueryExpressionVisitor visitor)
{
foreach (var query in Queries)
{
visitor.Visit(query);
}
}
public virtual void WriteHavingQueryParameters(
HavingQueryExpression whereQueryExpression,
QueryExpressionVisitor queryExpressionVisitor)
{
queryText.Append(" HAVING ");
queryExpressionVisitor.Visit(whereQueryExpression.Expression);
}
public virtual void WriteFromQueryParameter(
FromQueryExpression fromQueryExpression,
QueryExpressionVisitor queryExpressionVisitor)
{
queryText.Append(" FROM ");
queryExpressionVisitor.Visit(fromQueryExpression.Expression);
}
public virtual void WriteWhereQueryParameters(
WhereQueryExpression whereQueryExpression,
QueryExpressionVisitor queryExpressionVisitor)
{
queryText.Append(" WHERE ");
queryExpressionVisitor.Visit(whereQueryExpression.Expression);
}
public virtual void WriteDeleteStatement(
DeleteStatementQueryExpression deleteStatementQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
statementStack.Push(deleteStatementQueryExpression);
if (IsSubQuery())
{
queryText.Append(" ( ");
}
queryText.Append("DELETE ");
WriteIfNotNull(deleteStatementQueryExpression.From, queryExpressionVisitor);
WriteIfNotNull(deleteStatementQueryExpression.Where, queryExpressionVisitor);
if (IsSubQuery())
{
queryText.Append(" ) ");
}
else
{
queryText.Append("; ");
}
statementStack.Pop();
}
public virtual void WriteIsInOperator(
IsInOperatorQueryExpression isInFunctionCallQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
queryExpressionVisitor.Visit(isInFunctionCallQueryExpression.Expression);
if (isInFunctionCallQueryExpression.IsNotIn)
{
queryText.Append(" NOT ");
}
queryText.Append(" IN ");
var expressionsAreQueries = isInFunctionCallQueryExpression.InExpressions[0] is ExecutableQueryExpression;
if (!expressionsAreQueries)
{
queryText.Append("(");
}
WriteExpressionCollection(isInFunctionCallQueryExpression.InExpressions, queryExpressionVisitor);
if (!expressionsAreQueries)
{
queryText.Append(")");
}
queryText.Append(" ");
}
private static async Task ExecuteSubExpression(
QueryContext context,
QueryExpressionVisitor visitor,
IQueryExecutor executor,
Expression expression,
CancellationToken cancellationToken)
{
// 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.ConfigureAwait(false);
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);
}
}
public virtual void WriteGroupByQueryParameter(
GroupByCollectionQueryExpression groupByCollectionQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
queryText.Append(" GROUP BY ");
WriteExpressionCollection(groupByCollectionQueryExpression.Expressions, queryExpressionVisitor);
}
public virtual void WriteOrderByQueryParameter(
OrderByCollectionQueryExpression orderByCollectionQuery,
QueryExpressionVisitor queryExpressionVisitor
)
{
queryText.Append(" ORDER BY ");
WriteExpressionCollection(orderByCollectionQuery.Expressions, queryExpressionVisitor);
}
public virtual void WriteIntoQueryParameter(
IntoQueryExpression intoQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
queryText.Append(" INTO ");
queryExpressionVisitor.Visit(intoQueryExpression.Expression);
}
protected void WriteIfNotNull(QueryExpression queryExpression, QueryExpressionVisitor queryExpressionVisitor)
{
if (queryExpression == null)
{
return;
}
queryExpressionVisitor.Visit(queryExpression);
}
public override void WriteExtension(QueryExpression queryExpression, QueryExpressionVisitor queryExpressionVisitor)
{
if (queryExpression is ISqlServerExtension sqlServerExtension)
{
sqlServerExtension.Write(this, queryExpressionVisitor);
}
base.WriteExtension(queryExpression, queryExpressionVisitor);
}
public virtual void WriteCountFunction(
CountFunctionCallQueryExpression countFunctionCallQueryExpression,
QueryExpressionVisitor queryExpressionVisitor)
{
queryText.Append(" COUNT(");
WriteIfNotNull(countFunctionCallQueryExpression.Expression, queryExpressionVisitor);
queryText.Append(") ");
}
public override void WriteExtension(QueryExpression queryExpression, QueryExpressionVisitor queryExpressionVisitor)
{
if (queryExpression is IPostgresqlExtension postgresqlExtension)
{
postgresqlExtension.Write(this, queryExpressionVisitor);
}
base.WriteExtension(queryExpression, queryExpressionVisitor);
}
public override void WriteExtension(QueryExpression queryExpression, QueryExpressionVisitor queryExpressionVisitor)
{
if (queryExpression is IMySQLExtension mysqlExtension)
{
mysqlExtension.Write(this, queryExpressionVisitor);
}
base.WriteExtension(queryExpression, queryExpressionVisitor);
}
public virtual void WriteMaxFunction(
MaxFunctionCallQueryExpression maxFunctionCallQueryExpression,
QueryExpressionVisitor queryExpressionVisitor)
{
queryText.Append(" MAX(");
WriteIfNotNull(maxFunctionCallQueryExpression.Expression, queryExpressionVisitor);
queryText.Append(") ");
}
public static IEnumerable <Expression> Query(this Expression self, Func <Expression, bool> predicate)
{
var queryVisitor = new QueryExpressionVisitor(predicate);
queryVisitor.Visit(self);
return(queryVisitor.Expressions);
}
public virtual void WriteConcatFunction(
ConcatFunctionCallQueryExpression concatFunctionCallQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
queryText.Append(" CONCAT(");
WriteExpressionCollection(concatFunctionCallQueryExpression.Expressions, queryExpressionVisitor);
queryText.Append(") ");
}
public virtual void WriteAsOperator(
AsOperatorQueryExpression asFunctionCallQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
queryExpressionVisitor.Visit(asFunctionCallQueryExpression.Expression);
queryText.Append(" AS ");
WriteIdentifier(asFunctionCallQueryExpression.Alias, queryExpressionVisitor);
}
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);
}
public virtual void WriteOrderByExpressionQueryParameter(
OrderByQueryExpression orderByQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
WriteIfNotNull(orderByQueryExpression.Expression, queryExpressionVisitor);
if (orderByQueryExpression.Direction == OrderByDirection.Descending)
{
queryText.Append(" DESC ");
}
}
public virtual void WriteLastInsertedIdFunction(
LastInsertedIdFunctionCallExpression lastInsertedIdFunctionCallExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
// todo: decide what to do about this
// last insert id is literally different on every single platform
// the obvious thing to do would be to make QueryWriter abstract
// but that means writing an implementation of a writer for testing
// purposes and use in other contexts I can't think of now
throw new NotImplementedException();
}
public virtual void WriteLimitExpressionParameter(
LimitQueryExpression limitQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
queryText.Append(" LIMIT ");
WriteIfNotNull(limitQueryExpression.Limit, queryExpressionVisitor);
if (limitQueryExpression.Offset != null)
{
queryText.Append(" OFFSET ");
WriteIfNotNull(limitQueryExpression.Offset, queryExpressionVisitor);
}
}
public virtual void WriteSelectStatement(
SelectStatementQueryExpression selectStatementQueryExpression,
QueryExpressionVisitor queryExpressionVisitor)
{
statementStack.Push(selectStatementQueryExpression);
if (IsSubQuery())
{
queryText.Append(" ( ");
}
queryText.Append("SELECT ");
if (selectStatementQueryExpression.Projection == null || selectStatementQueryExpression.Projection.Expressions == null ||
selectStatementQueryExpression.Projection.Expressions.Length < 1)
{
throw new ProjectionMissingException("SELECT query must include a projection.");
}
queryExpressionVisitor.Visit(selectStatementQueryExpression.Projection);
WriteIfNotNull(selectStatementQueryExpression.From, queryExpressionVisitor);
if (selectStatementQueryExpression.Joins != null && selectStatementQueryExpression.Joins.Length > 0)
{
WriteExpressionCollection(selectStatementQueryExpression.Joins, queryExpressionVisitor, seperator: " ");
}
WriteIfNotNull(selectStatementQueryExpression.Where, queryExpressionVisitor);
WriteIfNotNull(selectStatementQueryExpression.GroupBy, queryExpressionVisitor);
WriteIfNotNull(selectStatementQueryExpression.Having, queryExpressionVisitor);
WriteIfNotNull(selectStatementQueryExpression.OrderBy, queryExpressionVisitor);
WriteIfNotNull(selectStatementQueryExpression.Limit, queryExpressionVisitor);
if (IsSubQuery())
{
queryText.Append(" ) ");
}
else
{
queryText.Append("; ");
}
statementStack.Pop();
}
DbCommandFactor GenerateCommandFactor()
{
IQueryState qs = QueryExpressionVisitor.VisitQueryExpression(this._query.QueryExpression);
MappingData data = qs.GenerateMappingData();
IObjectActivator objectActivator;
objectActivator = data.ObjectActivatorCreator.CreateObjectActivator();
IDbExpressionTranslator translator = this._query.DbContext._dbContextServiceProvider.CreateDbExpressionTranslator();
List <DbParam> parameters;
string cmdText = translator.Translate(data.SqlQuery, out parameters);
DbCommandFactor commandFactor = new DbCommandFactor(objectActivator, cmdText, parameters.ToArray());
return(commandFactor);
}
public virtual void WriteIdentifier(IdentifierQueryExpression identifierQueryExpression,
QueryExpressionVisitor queryExpressionVisitor)
{
if (identifierQueryExpression is NestedIdentifierQueryExpression nestedIdentifierQueryExpression &&
nestedIdentifierQueryExpression.ParentIdentifier != null)
{
WriteIdentifier(nestedIdentifierQueryExpression.ParentIdentifier, queryExpressionVisitor);
queryText.Append(".");
}
if (identifierQueryExpression.IdentifierName == "*")
{
queryText.Append(" * ");
}
else
{
queryText.Append($" [{identifierQueryExpression.IdentifierName}] ");
}
}
public virtual void WriteInsertStatement(
InsertStatementQueryExpression insertStatementQueryExpression,
QueryExpressionVisitor queryExpressionVisitor
)
{
statementStack.Push(insertStatementQueryExpression);
if (IsSubQuery())
{
queryText.Append(" ( ");
}
queryText.Append("INSERT ");
WriteIfNotNull(insertStatementQueryExpression.Into, queryExpressionVisitor);
queryText.Append(" ( ");
WriteExpressionCollection(insertStatementQueryExpression.Columns, queryExpressionVisitor);
queryText.Append(" ) ");
queryText.Append(" VALUES ");
for (var i = 0; i < insertStatementQueryExpression.RowsExpressions.Length; i++)
{
queryText.Append(" ( ");
WriteExpressionCollection(insertStatementQueryExpression.RowsExpressions[i], queryExpressionVisitor);
queryText.Append(" ) ");
if (i < insertStatementQueryExpression.RowsExpressions.Length - 1)
{
queryText.Append(", ");
}
}
if (IsSubQuery())
{
queryText.Append(" ) ");
}
else
{
queryText.Append("; ");
}
statementStack.Pop();
}
private static async Task ExecuteSubExpression(
QueryContext context,
QueryExpressionVisitor visitor,
IQueryExecutor executor,
Expression expression,
CancellationToken cancellationToken)
{
// 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>;
await task.ConfigureAwait(false);
// RWM: This code currently returns 404s if there are no results, instead of returning empty queries.
// This means that legit EntitySets that just have no data in the table also return 404. No bueno.
//var task = method.Invoke(executor, parameters) as Task<QueryResult>;
//var result = await task.ConfigureAwait(false);
//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);
//}
}
/// <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;
}
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;
}
