SymbolExist HOW

Example from file: examples/demos/lowlevel/01_general_operations.go

The SymbolExist() method is used to check whether a specific trading instrument (symbol) exists on the MetaTrader server. This is an important step before any actions with symbols — requesting information, subscribing to quotes, or trading operations.

It also reports whether the symbol is custom — created manually, rather than provided by the broker.

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🧩 Code example

fmt.Println("\n4.2. SymbolExist() - Check if symbol exists")

existReq := &pb.SymbolExistRequest{
    Name: cfg.TestSymbol, // Direct protobuf field: Name (not Symbol)
}
existData, err := account.SymbolExist(ctx, existReq)
if !helpers.PrintShortError(err, fmt.Sprintf("SymbolExist(%s) failed", cfg.TestSymbol)) {
    fmt.Printf("  Symbol '%s' exists:      %v\n", cfg.TestSymbol, existData.Exists)
    fmt.Printf("  Is custom symbol:         %v\n", existData.IsCustom)
}

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🟢 Detailed Code Explanation

🔹 Creating the request

existReq := &pb.SymbolExistRequest{
    Name: cfg.TestSymbol,
}

Creates a SymbolExistRequest request structure with the name of the symbol to check. Usually the value is taken from configuration (e.g., "EURUSD" from appsettings.json).

🔹 Method call

existData, err := account.SymbolExist(ctx, existReq)

Executes a gRPC call to the MetaTrader server.

• ctx — context (with or without timeout).
• existReq — request structure. Returns existData (protobuf response) and err — error if something went wrong.

🔹 Checking the result

if !helpers.PrintShortError(err, fmt.Sprintf("SymbolExist(%s) failed", cfg.TestSymbol)) {
    fmt.Printf("  Symbol '%s' exists:      %v\n", cfg.TestSymbol, existData.Exists)
    fmt.Printf("  Is custom symbol:         %v\n", existData.IsCustom)
}

If there is no error, two fields are printed:

• existData.Exists — true/false, shows whether the symbol was found on the server;
• existData.IsCustom — true/false, shows whether the symbol is custom.

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Example output

4.2. SymbolExist() - Check if symbol exists
  Symbol 'EURUSD' exists:      true
  Is custom symbol:            false

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What the server returns

message SymbolExistData {
  bool Exists = 1;     // true = symbol found
  bool IsCustom = 2;   // true = custom symbol
}

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Practical application example

symbol := "BTCUSD"
req := &pb.SymbolExistRequest{Name: symbol}
resp, err := account.SymbolExist(ctx, req)
if err != nil {
    log.Fatalf("Check failed: %v", err)
}

if !resp.Exists {
    log.Fatalf("Symbol %s not found on server", symbol)
}

if resp.IsCustom {
    fmt.Printf("%s is a custom (user-defined) symbol\n", symbol)
} else {
    fmt.Printf("%s is a standard market symbol\n", symbol)
}

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⚙️ What is a Custom Symbol

Custom symbol — is an instrument created manually by the user, rather than provided by the broker. For example:

• EURUSD → standard broker symbol;
• EURUSD.test → custom symbol.

Custom symbols are used for:

• quote simulation,
• strategy testing,
• manually loading custom data.

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💡 Practical use in gateway

Goal	Method
Check symbol existence	SymbolExist()
Activate symbol (add to Market Watch)	SymbolSelect(Symbol, true)
Get symbol information	SymbolInfo()
Subscribe to quotes	TicksSubscribe() or SymbolSubscribe()

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💬 In simple terms

SymbolExist() is a check: "Is there a symbol with this name on the MetaTrader server?" It returns two answers: does the symbol exist and what type is it — standard or custom.

Used at gateway startup, before trading or informational calls, to make sure the specified symbol is actually available on the server.