/// We compile each entityQuery with EqlCompiler and build a Select call from the fields
public override DataApiNode VisitEntityQuery(EqlGrammerParser.EntityQueryContext context)
{
string name;
string query;
if (context.alias != null)
{
name = context.alias.name.GetText();
query = context.entity.GetText();
}
else
{
query = context.entity.GetText();
name = query;
if (name.IndexOf(".") > -1)
{
name = name.Substring(0, name.IndexOf("."));
}
}
try
{
if (_selectContext == null)
{
// top level are queries on the context
var exp = EqlCompiler.Compile(query, _schemaProvider, _methodProvider).Expression;
var topLevelSelect = BuildDynamicSelectOnCollection(exp, name, context, true);
return(topLevelSelect);
}
// other levels are object selection. e.g. from the top level people query I am selecting all their children { field1, etc. }
return(BuildDynamicSelectForObjectGraph(query, name, context));
}
catch (EqlCompilerException ex)
{
//return DataApiNode.MakeError(name, $"Error compiling field or query '{query}'. {ex.Message}");
throw DataApiException.MakeFieldCompileError(query, ex.Message);
}
}
/// <summary>
/// Visit a parse tree produced by <see cref="EqlGrammerParser.entityQuery"/>.
/// <para>
/// The default implementation returns the result of calling <see cref="AbstractParseTreeVisitor{Result}.VisitChildren(IRuleNode)"/>
/// on <paramref name="context"/>.
/// </para>
/// </summary>
/// <param name="context">The parse tree.</param>
/// <return>The visitor result.</return>
public virtual Result VisitEntityQuery([NotNull] EqlGrammerParser.EntityQueryContext context)
{
return(VisitChildren(context));
}
/// Given a syntax of someField { fields, to, selection, from, object }
/// it will figure out if 'someField' is an IEnumerable or an istance of the object (not a collection) and build the correct select statement
private DataApiNode BuildDynamicSelectForObjectGraph(string query, string name, EqlGrammerParser.EntityQueryContext context)
{
if (!_schemaProvider.TypeHasField(_selectContext.Type.Name, name))
{
throw new EqlCompilerException($"Type {_selectContext.Type} does not have field or property {name}");
}
name = _schemaProvider.GetActualFieldName(_selectContext.Type.Name, name);
// Don't really like any of this, but...
try
{
var result = EqlCompiler.CompileWith(query, _selectContext, _schemaProvider, _methodProvider);
var exp = result.Expression;
if (exp.Body.Type.IsEnumerable())
{
return(BuildDynamicSelectOnCollection(exp, name, context, false));
}
var oldContext = _selectContext;
_selectContext = exp.Body;
// visit child fields. Will be field or entityQueries again
var fieldExpressions = context.fields.children.Select(c => Visit(c)).Where(n => n != null).ToList();
var relationsExps = fieldExpressions.Where(f => f.Expression.NodeType == ExpressionType.MemberInit || f.Expression.NodeType == ExpressionType.Call).ToList();
if (_relationHandler != null && relationsExps.Any())
{
var parameterExpression = Expression.Parameter(_selectContext.Type);
var relations = relationsExps.Select(r => (Expression)Expression.PropertyOrField(parameterExpression, r.Name)).ToList();
exp = _relationHandler.BuildNodeForSelect(relations, parameterExpression, exp, name, _schemaProvider);
}
var newExp = DataApiExpressionUtil.CreateNewExpression(_selectContext, fieldExpressions, _schemaProvider);
_selectContext = oldContext;
return(new DataApiNode(_schemaProvider.GetActualFieldName(_selectContext.Type.Name, name), newExp, exp.Parameters.Any() ? exp.Parameters.First() : null, exp.Body));
}
catch (EqlCompilerException ex)
{
throw DataApiException.MakeFieldCompileError(query, ex.Message);
}
}
/// Given a syntax of someCollection { fields, to, selection, from, object }
/// it will build a select assuming 'someCollection' is an IEnumerable
private DataApiNode BuildDynamicSelectOnCollection(LambdaExpression exp, string name, EqlGrammerParser.EntityQueryContext context, bool isRootSelect)
{
var elementType = exp.Body.Type.GetEnumerableType();
var contextParameter = Expression.Parameter(elementType);
var oldContext = _selectContext;
_selectContext = contextParameter;
// visit child fields. Will be field or entityQueries again
var fieldExpressions = context.fields.children.Select(c => Visit(c)).Where(n => n != null).ToList();
var relations = fieldExpressions.Where(f => f.Expression.NodeType == ExpressionType.MemberInit || f.Expression.NodeType == ExpressionType.Call).Select(r => r.RelationExpression).ToList();
// process at each relation
if (_relationHandler != null && relations.Any())
{
// Likely the EF handler to build .Include()s
exp = _relationHandler.BuildNodeForSelect(relations, contextParameter, exp, name, _schemaProvider);
}
// we're about to add the .Select() call. May need to do something
if (_relationHandler != null && isRootSelect)
{
exp = _relationHandler.HandleSelectComplete(exp);
}
// Default we select out sub objects/relations. So Select(d => new {Field = d.Field, Relation = new { d.Relation.Field }})
var selectExpression = DataApiExpressionUtil.SelectDynamic(contextParameter, exp.Body, fieldExpressions, _schemaProvider);
var node = new DataApiNode(name, selectExpression, exp.Parameters.Any() ? exp.Parameters.First() : null, exp.Body);
_selectContext = oldContext;
return(node);
}
