I am trying to save an enum as a comma-separated list in a DB.
I know I can do something like this to actually store a comma separated list:
part.MyProperty = new[] {"foo", "bar"};
and the DB would have an entry "foo, bar".
What I don't know how to do is how to store an enum, such as:
public enum Choices { Choice1, Choice2, Choice3 }
I gather I have to use Parse and ToString to use the enum values, but I am not sure how to do it.
This doesn't seem right:
part.MyProperty = new[] return from name in Enum.GetNames(typeof(T))
let enumValue = Convert.ToString((T)Enum.Parse(typeof(T), name, true))
Any thoughts?
What's wrong with part.MyProperty = Enum.GetNames(typeof(Choices)); ?
To get a comma separated list, use String.Join:
string csvEnums = string.Join(",", Enum.GetNames(typeof(Choices)));
String.Join(",", Enum.GetNames(typeof(Choices)));
Also you can build your own utitlity method that will get enums name in more nice syntax:
public static TEnum[] GetEnumValues<TEnum>() where TEnum : struct {
return (TEnum[])Enum.GetValues(typeof(TEnum));
}
and then:
Choices[] choices = GetEnumValues<Choices>();
or
part.MyProperty = GetEnumValues<Choices>().Select(n=>n.ToString()).ToArray();
[Flags]
public enum Choices {
Choice1 = 1,
Choice2 = 2,
Choice3 = 4
}
Choices a = Choices.Choice1 | Choices.Choice3;
Console.WriteLine(a.ToString());
outputs: Choice1, Choice3
Related
I am wondering if I can pass variable to be evaluated as String inside gstring evaluation.
simplest example will be some thing like
def var ='person.lName'
def value = "${var}"
println(value)
I am looking to get output the value of lastName in the person instance. As a last resort I can use reflection, but wondering there should be some thing simpler in groovy, that I am not aware of.
Can you try:
def var = Eval.me( 'new Date()' )
In place of the first line in your example.
The Eval class is documented here
edit
I am guessing (from your updated question) that you have a person variable, and then people are passing in a String like person.lName , and you want to return the lName property of that class?
Can you try something like this using GroovyShell?
// Assuming we have a Person class
class Person {
String fName
String lName
}
// And a variable 'person' stored in the binding of the script
person = new Person( fName:'tim', lName:'yates' )
// And given a command string to execute
def commandString = 'person.lName'
GroovyShell shell = new GroovyShell( binding )
def result = shell.evaluate( commandString )
Or this, using direct string parsing and property access
// Assuming we have a Person class
class Person {
String fName
String lName
}
// And a variable 'person' stored in the binding of the script
person = new Person( fName:'tim', lName:'yates' )
// And given a command string to execute
def commandString = 'person.lName'
// Split the command string into a list based on '.', and inject starting with null
def result = commandString.split( /\./ ).inject( null ) { curr, prop ->
// if curr is null, then return the property from the binding
// Otherwise try to get the given property from the curr object
curr?."$prop" ?: binding[ prop ]
}
I'm new to Grails and I've some troubles with queries. I got two domain classes like this:
class Cliente {
String nombre
String cuit
String localidad
String establecimiento
static hasMany = [facturas: Factura]
}
class Factura {
String Proveedor
int sucursal
String numero
String letraFactura
Cliente cliente
Date fecha
String tipo
}
I want to list all elements in facturas with client name:
Result expected:
Proveedor|sucursal|numero|cliente_nombre|fecha
I've tried some different ways but always get the cliente_id not cliente_nombre.
I think I know what you are asking: given a client name, return a list of factura's, with the stipulation that the list of fields should contain the client name rather than the client id.
import org.hibernate.criterion.CriteriaSpecification
// given a client name
def clientNameToSearch = 'some name'
def crit = Factura.createCriteria()
def results = crit.list() {
createAlias('cliente', 'cli')
eq('cli.nombre', clientNameToSearch)
// optional transformer to output a map rather than a list
resultTransformer(CriteriaSpecification.ALIAS_TO_ENTITY_MAP)
projections {
property('Proveedor', 'Proveedor')
property('sucursal', 'sucursal')
property('numero', 'numero')
property('cli.nombre', 'clienteNombre')
property('fecha', 'fecha')
}
}
results would then contain a list of maps, with each map having this structure:
[
Proveedor: ...,
sucursal: ...,
numero: ...,
clienteNombre: ...,
fecha: ...
]
I'm looking for a way to create a filtering system based upon tokenised query strings to return a list of farms.
The filtering mechanism would hopefully be flexible enough for me to supply the tokens in any order to return results.
The rules for search would be like this:
state:WA crop:Banana
would give me a filtered list of all farms in WA with the crop banana.
crop:Banana state:WA
should return the same result.
city:Albany crop:Banana
would give me a filtered list of all farms in Albany with the crop banana.
Each of the values supplied could be wrapped in quotation marks to allow space separated values to be grouped. e.g
city:"Mount barker" crop:Banana
would give me a filtered list of all farms in Mount Barker with the crop banana.
Furthermore any non tokenised queries would just look within a farms Details property to return the list of farms again with quotation marks combining multiple word queries.
---------------------------------------EDIT--------------------------------------------
My current search system using predicates is coded as follows. it's long (sorry) and is my first attempt though I'm hoping this could be refactored by some kind soul.
Many thanks in advance:
public ActionResult Search(string query, int? page)
{
IQueryable<Farm> farms = this.ReadOnlySession.All<Farm>();
if (!String.IsNullOrWhiteSpace(query))
{
// http://petemontgomery.wordpress.com/2011/02/10/a-universal-predicatebuilder
var predicate = PredicateBuilder.True<Farm>();
// We want to replace the spaces in quoted values here so we can split by space later.
// http://stackoverflow.com/questions/2148587/regex-quoted-string-with-escaped-quotes-in-c
Regex quoted = new Regex(#"""[^""\\]*(?:\\.[^""\\]*)*""");
foreach (var match in quoted.Matches(query))
{
query = query.Replace(match.ToString(), match.ToString().Replace(' ', '-'));
}
// Tidy up the query to remove "".
string[] splitQuery = HttpUtility.UrlDecode(query).Replace("\"", "").Split(' ');
Dictionary<string, string> tokenDictionary = new Dictionary<string, string>();
// Loop through our string[] and create a dictionary. Guids used to allow multiple keys
// of the same value.
Parallel.ForEach(splitQuery, subQuery =>
{
string[] tempArray = subQuery.Split(':');
if (tempArray.Length == 2)
{
tokenDictionary.Add(String.Format("{0}:{1}", tempArray[0], Guid.NewGuid()), tempArray[1]);
}
else
{
tokenDictionary.Add(String.Format("description:{0}", Guid.NewGuid()), subQuery);
}
});
// Loop through the dictionary and create our predicate.
foreach (KeyValuePair<string, string> item in tokenDictionary)
{
string value = item.Value.Replace('-', ' ');
string key = item.Key.Split(':')[0].ToUpperInvariant();
switch (key)
{
case "CROP":
value = Utilities.CreateSlug(value, OzFarmGuideConfig.RemoveDiacritics);
predicate = predicate.And(x => x.Crops.Any(y => value.Equals(y.Slug, StringComparison.OrdinalIgnoreCase)));
break;
case "STATE":
predicate = predicate.And(x => value.Equals(x.City.State.Name, StringComparison.OrdinalIgnoreCase));
break;
case "CITY":
value = Utilities.CreateSlug(value, OzFarmGuideConfig.RemoveDiacritics);
predicate = predicate.And(x => value.Equals(x.City.Slug, StringComparison.OrdinalIgnoreCase));
break;
default:
predicate = predicate.And(x => !String.IsNullOrWhiteSpace(x.Details) && x.Details.Contains(value));
break;
}
}
farms = farms.Where(predicate).OrderByDescending(x => x.Rating)
.ThenByDescending(x => x.RatingVotes);
PagedList<Farm> pagedFarms = new PagedList<Farm>(farms, page.HasValue ? page.Value - 1 : 0, 5);
return View(pagedFarms);
}
else
{
PagedList<Farm> pagedFarms = null;
return View(pagedFarms);
}
}
Just a guess, would the problem correct itself with the introduction of DefaultIfEmpty()?
default:
// This is not working at the mo. Getting a null exception when we try
// to initialise PagedList.
predicate = predicate.And(x => x.Details.DefaultIfEmpty().Contains(value));
break;
Question: how can I insert a table from C# into 'LuaInterface' script scope using a C# object (preferably anonymous type)?
/// I want to do this, but it does not work
/// (complains that 'test' is userdata and not table
/// when I pass it to pairs() in the script)
//lua["test"] = new { A = 1, B = 2 };
/// another option
/// but building this string is a PITA (actual string is nested and long).
lua.DoString("test = { A = 1, B = 2 }");
// So I have to do this
lua.NewTable("test");
((LuaTable) lua["test"])["A"] = 1;
((LuaTable) lua["test"])["B"] = 2;
lua.DoString("for k,v in pairs(test) do print(k..': '..v) end");
You could fill a C# Dictionary with the keys and values you want to put inside the table. Then do what you're doing in the "I have to..." section, but inside a foreach loop.
Untested code:
var test = new Dictionary<string, int> {
{ "A", 1 },
{ "B", 2 }
};
foreach (var entry in test)
{
((LuaTable) lua]["test"])[entry.Key] = entry.Value;
}
I'd refactor this basic idea into a generic class for added flexibility.
I think if you want to serialize anonymous types into lua tables you will need to user reflection. Maybe you can try to write a lua table serializer. I think I would try to assemble my tables as string and pass it to Lua with DoString
I think the dictionary solution is good and you can use nested tables with without reflection. I tried Tuples, but they are not generic enough and eventually I fell back to the reflection idea.
I would create an extension method:
public static class LuaExt
{
public static LuaTable GetTable(this Lua lua, string tableName)
{
return lua[tableName] as LuaTable;
}
public static LuaTable CreateTable(this Lua lua, string tableName)
{
lua.NewTable(tableName);
return lua.GetTable(tableName);
}
public static LuaTable CreateTable(this Lua lua)
{
lua.NewTable("my");
return lua.GetTable("my");
}
}
Then I could write something like this:
var lua = new Lua();
var table = lua.CreateTable("test");
table["A"] = 1;
table["B"] = 1;
table["C"] = lua.CreateTable();
((LuaTable) table["C"])["A"] = 3;
table["D"] = lua.CreateTable();
((LuaTable)table["D"])["A"] = 3;
foreach (var v in table.Keys)
{
Console.WriteLine(v + ":" + table[v]);
}
I'm trying to write 2 extension methods to handle Enum types. One to use the description attribute to give some better explanation to the enum options and a second method to list the enum options and their description to use in a selectlist or some kind of collection.
You can read my code up to now here:
<Extension()> _
Public Function ToDescriptionString(ByVal en As System.Enum) As String
Dim type As Type = en.GetType
Dim entries() As String = en.ToString().Split(","c)
Dim description(entries.Length) As String
For i = 0 To entries.Length - 1
Dim fieldInfo = type.GetField(entries(i).Trim())
Dim attributes() = DirectCast(fieldInfo.GetCustomAttributes(GetType(DescriptionAttribute), False), DescriptionAttribute())
description(i) = If(attributes.Length > 0, attributes(0).Description, entries(i).Trim())
Next
Return String.Join(", ", description)
End Function
<Extension()> _
Public Function ToListFirstTry(ByVal en As System.Enum) As IEnumerable
Dim type As Type = en.GetType
Dim items = From item In System.Enum.GetValues(type) _
Select New With {.Value = item, .Text = item.ToDescriptionString}
Return items
End Function
<Extension()> _
Public Function ToListSecondTry(ByVal en As System.Enum) As IEnumerable
Dim list As New Dictionary(Of Integer, String)
Dim enumValues As Array = System.Enum.GetValues(en.GetType)
For Each value In enumValues
list.Add(value, value.ToDescriptionString)
Next
Return list
End Function
So my problem is both extension methods don't work that well together. The methods that converts the enum options to an ienumerable can't use the extension method to get the description.
I found all kind of examples to do one of both but never in combination with each other. What am I doing wrong? I still new to these new .NET 3.5 stuff.
The problem is that Enum.GetValues just returns a weakly typed Array.
Try this:
Public Function ToListFirstTry(ByVal en As System.Enum) As IEnumerable
Dim type As Type = en.GetType
Dim items = From item In System.Enum.GetValues(type).Cast(Of Enum)() _
Select New With {.Value = item, .Text = item.ToDescriptionString}
Return items
End Function
(It looks like explicitly typed range variables in VB queries don't mean the same thing as in C#.)