internal void UpdatePropertyBasedOnAliasFromInputSchema(QueryExpressionProperty prop)
{
var matchedField = InputSchema.FirstOrDefault(f => f.FieldAlias == prop.VariableName);
if (matchedField == null)
{
throw new TranspilerBindingException($"Alias '{prop.VariableName}' does not exist in the current context");
}
if (string.IsNullOrEmpty(prop.PropertyName))
{
// direct reference to an alias (value column or entity column)
if (matchedField is ValueField)
{
prop.DataType = (matchedField as ValueField).FieldType;
}
else
{
// entity field reference in a single field expression
// this is valid only in handful situations, such as Count(d), Count(distinct(d))
// in such case, we populate the Entity object with correct entity type so that code generator can use it later
Debug.Assert(matchedField is EntityField);
var matchedEntity = matchedField as EntityField;
prop.Entity = matchedEntity.Type == EntityField.EntityType.Node ?
new NodeEntity()
{
EntityName = matchedEntity.EntityName, Alias = matchedEntity.FieldAlias
} as Entity :
new RelationshipEntity()
{
EntityName = matchedEntity.EntityName, Alias = matchedEntity.FieldAlias
} as Entity;
}
}
else
{
// property dereference of an entity column
if (!(matchedField is EntityField))
{
throw new TranspilerBindingException($"Failed to dereference property {prop.PropertyName} for alias {prop.VariableName}, which is not an alias of entity type as expected");
}
var entField = matchedField as EntityField;
var entPropField = entField.EncapsulatedFields.FirstOrDefault(f => f.FieldAlias == prop.PropertyName);
if (entPropField == null)
{
throw new TranspilerBindingException($"Failed to dereference property {prop.PropertyName} for alias {prop.VariableName}, Entity type {entField.BoundEntityName} does not have a property named {prop.PropertyName}");
}
entField.AddReferenceFieldName(prop.PropertyName);
prop.DataType = entPropField.FieldType;
}
}
internal override void PropagateDateTypesForOutSchema()
{
// projection may alter the schema with calculated columns
// we calculate the data type of all the fields in the output schema
// using type evaluation method on the QueryExpression
var exprToOutputMap = ProjectionMap.ToDictionary(
kv => kv.Key, // key is output alias
kv => new { Expr = kv.Value, Field = OutputSchema.First(f => f.FieldAlias == kv.Key) } // value is the corresponding field object and expression
);
foreach (var map in exprToOutputMap)
{
// toggle the fact if any of the output column requires aggregation
HasAggregationField = HasAggregationField ||
(map.Value.Expr.GetChildrenQueryExpressionType <QueryExpressionAggregationFunction>().Count() > 0);
var allPropertyReferences = map.Value.Expr.GetChildrenQueryExpressionType <QueryExpressionProperty>();
if (map.Value.Field is EntityField)
{
// This can only be direct exposure of entity (as opposed to deference of a particular property)
// We just copy of the fields that the entity can potentially be dereferenced
Debug.Assert(allPropertyReferences.Count() == 1);
var varName = allPropertyReferences.First().VariableName;
var matchInputField = InputSchema.First(f => f.FieldAlias == varName);
map.Value.Field.Copy(matchInputField);
}
else
{
// This can be a complex expression involve multiple field/column references
// We will compute the type of the expression
Debug.Assert(map.Value.Field is ValueField);
// first of all, bind the type to the variable references
foreach (var prop in allPropertyReferences)
{
var varName = prop.VariableName;
var propName = prop.PropertyName;
Debug.Assert(prop.VariableName != null);
var matchedField = InputSchema.FirstOrDefault(f => f.FieldAlias == varName);
if (matchedField == null)
{
throw new TranspilerBindingException($"Failed to find input matching field alias {varName}");
}
if (string.IsNullOrEmpty(propName))
{
// direct reference to an alias (value column or entity column)
if (matchedField is ValueField)
{
prop.DataType = (matchedField as ValueField).FieldType;
}
else
{
// entity field reference in a single field expression
// this is valid only in handful situations, such as Count(d), Count(distinct(d))
// in such case, we populate the Entity object with correct entity type so that code generator can use it later
Debug.Assert(matchedField is EntityField);
var matchedEntity = matchedField as EntityField;
prop.Entity = matchedEntity.Type == EntityField.EntityType.Node ?
new NodeEntity()
{
EntityName = matchedEntity.EntityName, Alias = matchedEntity.FieldAlias
} as Entity:
new RelationshipEntity()
{
EntityName = matchedEntity.EntityName, Alias = matchedEntity.FieldAlias
} as Entity;
}
}
else
{
// property dereference of an entity column
if (!(matchedField is EntityField))
{
throw new TranspilerBindingException($"Failed to dereference property {propName} for alias {varName}, which is not an alias of entity type as expected");
}
var entField = matchedField as EntityField;
var entPropField = entField.EncapsulatedFields.FirstOrDefault(f => f.FieldAlias == propName);
if (entPropField == null)
{
throw new TranspilerBindingException($"Failed to dereference property {propName} for alias {varName}, Entity type {entField.BoundEntityName} does not have a property named {propName}");
}
entField.AddReferenceFieldName(propName);
prop.DataType = entPropField.FieldType;
}
}
// do data type evaluation
var evalutedType = map.Value.Expr.EvaluateType();
var outField = map.Value.Field as ValueField;
outField.FieldType = evalutedType;
}
}
}