Document System Tutorial Part 9 - Updating the Document Version¶

In this part, we will talk about updating the document version automatically if the file has changed by the user after saving the specific document in the model.

First of all, go to document.go in the models folder. Create a Save function below the model struct. Inside it, create two variables named docChange and newDoc. Set both of them to false.

// Save !
func (d *Document) Save() {
    // Initialized variables
    docChange := false
    newDoc := false
}

Now let’s create a validation that checks whether the document record is new or existing to be done by the user. If the document ID is not 0, the record is existing. Otherwise, the user is creating a new document. Put it below the newDoc variable.

// Checks whether the document record is new or existing
if d.ID != 0 {
    // Initializes the Document model
    oldDoc := Document{}

    // Gets the ID of the old Document
    uadmin.Get(&oldDoc, "id = ?", d.ID)

    // Checks if the file is changed or updated
    if d.File != oldDoc.File {
        docChange = true
    }
} else {
    // New document record
    docChange = true
    newDoc = true
}

// Save the Document
uadmin.Save(d)

Create a validation that checks if the document is changed, the document version number will automatically get updated.

// Checks whether the document record has changed
if docChange {
    // Sets the document value to the DocumentVersion fields
    ver := DocumentVersion{}
    ver.Date = time.Now()
    ver.DocumentID = d.ID
    ver.File = d.File
    ver.Format = d.Format

    // Counts the version number based on the DocumentID and increment it
    // by 1
    ver.Number = uadmin.Count([]DocumentVersion{}, "document_id = ?", d.ID) + 1

    // Save the document version
    uadmin.Save(&ver)
}

Below the uadmin.Save(&ver) inside the docChange validation, create another validation that checks if the document is a new record, it will set the values to the DocumentVersion model fields.

// Sets values to the DocumentUser model fields
creator := DocumentUser{
    UserID:     user.ID,
    DocumentID: d.ID,
    Read:       true,
    Edit:       true,
    Add:        true,
    Delete:     true,
}

// Save the document user
uadmin.Save(&creator)