The additional logic that we added is related to the SetExpression method.
We have helper code that constructs the JSON query and then passes it to the base SetExpression method.
In that helper, we are using the ObjectAlias property on the base EntityField2 class but it the moment we are using it, it still has the alias that we set to it (i.e. "A").
The main logic is in the GetJsonFieldExpression method and that's the source of the problem currently.
Here is our example class:
public class JsonEntityField : EntityField2
{
protected const string sqlExpression = "({0}){{2}}";
protected const string sqlExpressionCast = "({0})::{{2}}";
protected string dbType = null;
protected string jsonDbFieldName = null;
protected Type systemType = null;
private static Type stringType = typeof(string);
private IExpression jsonFieldExpression = null;
public JsonEntityField(string field)
: this(String.Empty, field, String.Empty, stringType)
{
}
public JsonEntityField(string jsonDbFieldName, string field)
: this(jsonDbFieldName, field, String.Empty, stringType)
{
}
public JsonEntityField(string jsonDbFieldName, string field, string dbType, Type systemType)
: this(jsonDbFieldName, field, dbType, systemType, null, null)
{
}
public JsonEntityField(string jsonDbFieldName, string field, string dbType, Type systemType, string fieldAlias, string objectAlias)
: base(field, null, AggregateFunction.None, systemType, objectAlias, 0, 0, 0)
{
jsonFieldExpression = GetJsonFieldExpression(jsonDbFieldName, field, dbType);
SetExpression(jsonFieldExpression);
if (!string.IsNullOrWhiteSpace(fieldAlias))
{
this.SetFieldAlias(fieldAlias);
}
this.systemType = systemType;
this.jsonDbFieldName = jsonDbFieldName;
this.dbType = dbType;
}
protected virtual IExpression GetJsonFieldExpression(string jsonDbFieldName, string field, string dbType)
{
Func<string> compile = () =>
{
if (String.IsNullOrWhiteSpace(jsonDbFieldName))
{
jsonDbFieldName = "Json";
}
if (String.IsNullOrWhiteSpace(field))
{
throw new BaasicArgumentNullException("field");
}
string sqlExpressionResult = null;
if (!String.IsNullOrWhiteSpace(dbType))
{
sqlExpressionResult = sqlExpressionCast;
}
else
{
dbType = null;
sqlExpressionResult = sqlExpression;
}
string result = null;
string parsedField = field.Trim(' ').Trim('.');
if (parsedField.Contains('.'))
{
//where ("Json"->'Object'->'Object2'->>'SubObjField2')::int > 3
StringBuilder exp = new StringBuilder();
List<string> tokens = new List<string>(parsedField.Split('.'));
for (int i = 0; i < tokens.Count; i++)
{
if (!String.IsNullOrWhiteSpace(tokens[i]))
{
exp.Append(String.Format("-{0}'{1}'", i == tokens.Count - 1 ? ">>" : ">", tokens[i]));
}
}
sqlExpressionResult = String.Format(sqlExpressionResult, "\"{0}\"{1}");
result = String.Format(sqlExpressionResult, jsonDbFieldName, exp.ToString(), dbType);
}
else
{
sqlExpressionResult = String.Format(sqlExpressionResult, "\"{0}\"->>'{1}'");
result = String.Format(sqlExpressionResult, jsonDbFieldName, field, dbType);
}
if (!string.IsNullOrWhiteSpace(this.ObjectAlias))
{
result = $"\"{ObjectAlias}\".{result}";
}
if (!string.IsNullOrWhiteSpace(this.Alias) && !this.Alias.Equals(this.Name))
{
result = $"{result} AS \"{Alias}\"";
}
return result;
};
return new LazyRawExpression(compile);
}
}
