Query

Introduction

Queries are used in Datastorms to select instance data. For instance, you might use one to populate a table on a page or to generate a report in the reporting editor. Creating a query in Datastorms is made easy with our specially developed no-code methodology.

Basics

Each query is composed of two main elements:

1. The root schema, which serves as the starting point for the query.
2. The query's content itself.

Root schema selection

Any scheme can be selected as a root scheme for a query. The root-scheme is where the query starts gathering instance data.

Content selection

A dropdown-list will become available with in the root the selected root-scheme. Select the required properties of the root-scheme.

When properties of related scheme's are required, click on the arrow in front of the relation-name.

In Tree's it is possible to also select recursive relations. In this case only the recursive relation needs to be selected. The properties of the top-scheme will be used for all child (or parent if selected this relation) instances.

Property Indicators (* and !)

When selecting properties in the dropdown-list, you might see special characters next to some property names. These indicators help you understand the constraints of the data you are querying:

• Asterisk (*): Indicates that the property is Required. This means every instance of this schema will always have a value for this property, and it cannot be empty.
• Exclamation mark (!): Indicates that the property is Unique. This means that the value of this property must be distinct across all instances in the schema.

Properties can also have both indicators (*!), meaning the field is both mandatory and unique.

Filtering

Default all instance data is queried. You can define filters in the filtering section to display only a subset of the data in your query results. To add a simple filter, click the green "+"-button in the filtering section. A new filter will then appear, which you can configure as desired.

Single Filter

1. First choose the property you want to apply the filter to, such as a person's "Name."
2. Next set the comparison method for the filter. This depends on the property's ValueType. For a String (text), options include:
   • Contains
   • Starts with
   • Ends with
   • Equals
3. Then define the value compare to.

Example

An example of a string filter can be: "Only show Persons with Name Equals Jan-Willem."

When clicking on the dropdown next to the filter some additional options become available:

• Negate filter: if the filter represents a negation, set the Negate filter toggle to true. For example, this could be a statement like: "All names except 'Jan-Willem'.".
• User setable filter: This indicates whether the value set in step 4 can be changed by the end-user (e.g. for a table or report). The value entered in step 3 then becomes the default.
• Label: you can name the filter for the end-user's input value.

Multiple Filters

It's possible to have more than one filter in a query by clicking the green "+" button again. Now you'll need to make some configuration choices:

• Are the filter results complimentory (OR) or restrictive (AND)?
• Are more complex grouping of filters required for the desired logic?