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Fix C# Module Quickstart Guide Syntax Highlighting #10

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Oct 26, 2023
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Fix C# Module Quickstart Guide Syntax Highlighting #10

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192 changes: 96 additions & 96 deletions docs/Server Module Languages/C#/index.md
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,7 @@ spacetime init --lang csharp server

To the top of `server/Lib.cs`, add some imports we'll be using:

```C#
```csharp
using System.Runtime.CompilerServices;
using SpacetimeDB.Module;
using static SpacetimeDB.Runtime;
Expand All @@ -66,29 +66,29 @@ For each `User`, we'll store their `Identity`, an optional name they can set to

In `server/Lib.cs`, add the definition of the table `User` to the `Module` class:

```C#
[SpacetimeDB.Table]
public partial class User
{
[SpacetimeDB.Column(ColumnAttrs.PrimaryKey)]
public Identity Identity;
public string? Name;
public bool Online;
}
```csharp
[SpacetimeDB.Table]
public partial class User
{
[SpacetimeDB.Column(ColumnAttrs.PrimaryKey)]
public Identity Identity;
public string? Name;
public bool Online;
}
```

For each `Message`, we'll store the `Identity` of the user who sent it, the `Timestamp` when it was sent, and the text of the message.

In `server/Lib.cs`, add the definition of the table `Message` to the `Module` class:

```C#
[SpacetimeDB.Table]
public partial class Message
{
public Identity Sender;
public long Sent;
public string Text = "";
}
```csharp
[SpacetimeDB.Table]
public partial class Message
{
public Identity Sender;
public long Sent;
public string Text = "";
}
```

## Set users' names
Expand All @@ -101,19 +101,19 @@ It's also possible to call `SetName` via the SpacetimeDB CLI's `spacetime call`

In `server/Lib.cs`, add to the `Module` class:

```C#
[SpacetimeDB.Reducer]
public static void SetName(DbEventArgs dbEvent, string name)
{
name = ValidateName(name);
```csharp
[SpacetimeDB.Reducer]
public static void SetName(DbEventArgs dbEvent, string name)
{
name = ValidateName(name);

var user = User.FindByIdentity(dbEvent.Sender);
if (user is not null)
{
user.Name = name;
User.UpdateByIdentity(dbEvent.Sender, user);
}
var user = User.FindByIdentity(dbEvent.Sender);
if (user is not null)
{
user.Name = name;
User.UpdateByIdentity(dbEvent.Sender, user);
}
}
```

For now, we'll just do a bare minimum of validation, rejecting the empty name. You could extend this in various ways, like:
Expand All @@ -126,16 +126,16 @@ For now, we'll just do a bare minimum of validation, rejecting the empty name. Y

In `server/Lib.cs`, add to the `Module` class:

```C#
/// Takes a name and checks if it's acceptable as a user's name.
public static string ValidateName(string name)
```csharp
/// Takes a name and checks if it's acceptable as a user's name.
public static string ValidateName(string name)
{
if (string.IsNullOrEmpty(name))
{
if (string.IsNullOrEmpty(name))
{
throw new Exception("Names must not be empty");
}
return name;
throw new Exception("Names must not be empty");
}
return name;
}
```

## Send messages
Expand All @@ -144,35 +144,35 @@ We define a reducer `SendMessage`, which clients will call to send messages. It

In `server/Lib.cs`, add to the `Module` class:

```C#
[SpacetimeDB.Reducer]
public static void SendMessage(DbEventArgs dbEvent, string text)
```csharp
[SpacetimeDB.Reducer]
public static void SendMessage(DbEventArgs dbEvent, string text)
{
text = ValidateMessage(text);
Log(text);
new Message
{
text = ValidateMessage(text);
Log(text);
new Message
{
Sender = dbEvent.Sender,
Text = text,
Sent = dbEvent.Time.ToUnixTimeMilliseconds(),
}.Insert();
}
Sender = dbEvent.Sender,
Text = text,
Sent = dbEvent.Time.ToUnixTimeMilliseconds(),
}.Insert();
}
```

We'll want to validate messages' texts in much the same way we validate users' chosen names. As above, we'll do the bare minimum, rejecting only empty messages.

In `server/Lib.cs`, add to the `Module` class:

```C#
/// Takes a message's text and checks if it's acceptable to send.
public static string ValidateMessage(string text)
```csharp
/// Takes a message's text and checks if it's acceptable to send.
public static string ValidateMessage(string text)
{
if (string.IsNullOrEmpty(text))
{
if (string.IsNullOrEmpty(text))
{
throw new ArgumentException("Messages must not be empty");
}
return text;
throw new ArgumentException("Messages must not be empty");
}
return text;
}
```

You could extend the validation in `ValidateMessage` in similar ways to `ValidateName`, or add additional checks to `SendMessage`, like:
Expand All @@ -188,56 +188,56 @@ We'll use `User.FilterByIdentity` to look up a `User` row for `dbEvent.Sender`,

In `server/Lib.cs`, add the definition of the connect reducer to the `Module` class:

```C#
[SpacetimeDB.Reducer(ReducerKind.Connect)]
public static void OnConnect(DbEventArgs dbEventArgs)
{
Log($"Connect {dbEventArgs.Sender}");
var user = User.FindByIdentity(dbEventArgs.Sender);
```csharp
[SpacetimeDB.Reducer(ReducerKind.Connect)]
public static void OnConnect(DbEventArgs dbEventArgs)
{
Log($"Connect {dbEventArgs.Sender}");
var user = User.FindByIdentity(dbEventArgs.Sender);

if (user is not null)
{
// If this is a returning user, i.e., we already have a `User` with this `Identity`,
// set `Online: true`, but leave `Name` and `Identity` unchanged.
user.Online = true;
User.UpdateByIdentity(dbEventArgs.Sender, user);
}
else
if (user is not null)
{
// If this is a returning user, i.e., we already have a `User` with this `Identity`,
// set `Online: true`, but leave `Name` and `Identity` unchanged.
user.Online = true;
User.UpdateByIdentity(dbEventArgs.Sender, user);
}
else
{
// If this is a new user, create a `User` object for the `Identity`,
// which is online, but hasn't set a name.
new User
{
// If this is a new user, create a `User` object for the `Identity`,
// which is online, but hasn't set a name.
new User
{
Name = null,
Identity = dbEventArgs.Sender,
Online = true,
}.Insert();
}
Name = null,
Identity = dbEventArgs.Sender,
Online = true,
}.Insert();
}
}
```

Similarly, whenever a client disconnects, the module will execute the `OnDisconnect` event if it's registered with `ReducerKind.Disconnect`. We'll use it to un-set the `Online` status of the `User` for the disconnected client.

Add the following code after the `OnConnect` lambda:

```C#
[SpacetimeDB.Reducer(ReducerKind.Disconnect)]
public static void OnDisconnect(DbEventArgs dbEventArgs)
{
var user = User.FindByIdentity(dbEventArgs.Sender);
```csharp
[SpacetimeDB.Reducer(ReducerKind.Disconnect)]
public static void OnDisconnect(DbEventArgs dbEventArgs)
{
var user = User.FindByIdentity(dbEventArgs.Sender);

if (user is not null)
{
// This user should exist, so set `Online: false`.
user.Online = false;
User.UpdateByIdentity(dbEventArgs.Sender, user);
}
else
{
// User does not exist, log warning
Log($"Warning: No user found for disconnected client.");
}
if (user is not null)
{
// This user should exist, so set `Online: false`.
user.Online = false;
User.UpdateByIdentity(dbEventArgs.Sender, user);
}
else
{
// User does not exist, log warning
Log($"Warning: No user found for disconnected client.");
}
}
```

## Publish the module
Expand Down