Therefore my precondition as boolean value: The model is working but calculates cell statistics for all input rasters, not only for the summer months. When you click OK, a precondition connector line appears between the variable and tool. Cell Statistics shall be calculated for only those rasters dating in summer months (April - October), input raster name format is yYYYYmMM, e.g. You can add multiple preconditions if needed. Click the Properties tab, then click the Precondition drop-down arrow to select the variable. Open the tool by double-clicking the tool, or right-clicking and clicking Open.Click on the desired variable and while holding the left mouse button move the cursor to the tool, then release the mouse button on top of the tool to make a precondition connector line between the variable and tool.To make a variable a precondition of a tool, use one of the following techniques: Must be made a precondition to the Clip tool.īy doing this, the Clip tool will run after Create Feature Dataset and the Output Feature Dataset has been created. In the model below, the Output Feature Dataset variable The Clip tool may execute before its output location is even created, resulting in an error. If the model above is executed as-is, there is no way to control the order of operations. The second process clips a feature class to a study area and writes the output to the newly created feature dataset. The first string of processes creates a newįeature dataset within a new file geodatabase. In this example, two separate but related processes will be connected using a precondition so that one process executesīefore the other. BPMN uses standardised graphical symbols to express business workflow processes. The commonly used languages are BPMN 30 and XPDL 38. Workflow models are usually denoted by graphical symbols and descriptive language. Any variable can be made a precondition to tool execution, and any tool can have more than one precondition. workflow model and the graph-based workflow model can be exchanged by defining the transformation rules. A process can be made to run after another process by making the output of the first process a precondition to the second process. In such cases, preconditions can be used to explicitly control the order of operations.
![model builder precondition model builder precondition](https://i.stack.imgur.com/EscVE.png)
However, occasionally you may need to control the order of operations between two related but disconnected processes. This happens automatically as you make connections using the output of one tool as the input to another tool. ModelBuilder has a built-in understanding of which processes in your model need to run first so that dependent processes have the data needed to run successfully. ModelBuilder has a built-in understanding of which processes in your model need to run first so that dependent processes have the data needed to run.