🔍 Understanding Table Methods in X++: initValue(), validateWrite(), validateDelete(), modifiedField(), and validate()

Author: Sai Krishna
Title: Understanding Table Methods in X++: initValue(), validateWrite(), validateDelete(), modifiedField(), and validate()

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If you're working with Microsoft Dynamics 365 Finance and Operations (D365FO) or AX 2012, understanding how table methods function in X++ is essential for enforcing business logic and data validation. In this post, we’ll dive into the most commonly used table methods: initValue(), validateWrite(), validateDelete(), modifiedField(), and validate()—complete with real-world X++ code examples and best practices.

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📌 1. initValue() Method in X++

The initValue() method is executed when a new record is created. It's commonly used to initialize default values for fields.

✅ Example:

x++
public void initValue()
{
    super();
    this.UserId = curUserId(); // Automatically assign current user
}

Use Case: Automatically set the current user ID whenever a new record is inserted.

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📌 2. validateDelete() Method

This method is triggered before deleting a record. It’s used to place conditions on whether the deletion is allowed.

✅ Example 1 – Simple Info Display:

x++
public boolean validateDelete()
{
    boolean ret = super();
    info(this.AccountNum); // Show deleted AccountNum
    return ret;
}

✅ Example 2 – Conditional Deletion Logic:

x++
public boolean validateDelete()
{
    boolean ret = super();

    if (this.TECClaimInStatus == TECClaimInStatus::Posted ||
        this.TECClaimInStatus == TECClaimInStatus::Received ||
        this.TECClaimOutStatus == TECClaimOutStatus::Posted ||
        this.TECClaimOutStatus == TECClaimOutStatus::Delivered)
    {
        ret = false;
        warning("Cannot delete lines!");
    }

    return ret;
}

Best Practice: Use validateDelete() to ensure that posted or processed records aren't deleted accidentally.

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📌 3. validateWrite() Method

This method is called when creating or updating a record. Use it to perform field-level validations.

✅ Example 1 – Mandatory Field Check:

x++
public boolean validateWrite()
{
    boolean ret = true;

    if (this.Address == "")
    {
        warning("Please fill in the address value.");
        ret = false;
    }
    else
    {
        ret = super();
    }

    return ret;
}

✅ Example 2 – Validate Custom Logic:

x++
public boolean validateWrite()
{
    boolean ret = super();

    if (!purchEditLinesForm.validateInventDimId(purchParmLine, inventDim))
    {
        ret = false;
    }

    if (!TIDCorrectPackingSlip_Remark.mandatory())
    {
        ret = false;
        error("Remark is required.");
    }

    return ret;
}

Pro Tip: Always call super() to inherit standard validation unless you intend to override it entirely.

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📌 4. modifiedField() Method

This method is fired when a field value changes. It’s useful for auto-populating or recalculating dependent fields.

✅ Example:

x++
public void modifiedField(fieldId _fieldId)
{
    super(_fieldId);

    switch (_fieldId)
    {
        case fieldNum(Cust_new, AccountNum):
            this.Name = CustTable::find(this.AccountNum).Name;
            break;
    }
}

Use Case: Automatically populate the customer name based on the selected account number.

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📌 5. validate() Method

The validate() method is a general validation method that can be used on form-level or field-level validation scenarios.

✅ Example 1 – Date Validations:

x++
public boolean validate()
{
    boolean ret = super();

    if (monthOfYear(ToDate.dateValue()) != monthOfYear(FromDate.dateValue()))
    {
        warning("To Date must be in the same month as From Date.");
        ret = false;
    }

    if (ToDate.dateValue() < FromDate.dateValue())
    {
        warning("To Date cannot be earlier than From Date.");
        ret = false;
    }

    return ret;
}

✅ Example 2 – Confirmation Box:

x++
public boolean validate()
{
    boolean ret = super();

    if (ret)
    {
        if (this.value() && logisticsElectronicAddress.otherPrimaryExists())
        {
            if (Box::yesNo("@SYS304427", DialogButton::No) == DialogButton::No)
            {
                ret = false;
            }
        }
    }

    return ret;
}

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🔎 Summary

Method	Triggered When	Common Use Case
initValue()	On record creation	Default field initialization
validateDelete()	Before deleting a record	Prevent deletion based on business rules
validateWrite()	On create or update of a record	Mandatory fields and custom validations
modifiedField()	When a field value is modified	Auto-filling or triggering dependent changes
validate()	During validation before saving	Field-level or business logic validations

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